THE SOVIET JOURNAL OF ATOMIC ENERGY VOL. 4 NO. 6

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• Publication Date: June 1, 1958
• Content Type: REPORT

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THE SOVIET JOURNAL OF
vol. 4, no. 6
June , 1.968
OMIC ENERGY
ATOMHa51
3Heprlim
TRANSLATED FROM RUSSIAN
CONSULTANTS BUREAU, iNC.
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1 recent Russian research -
1 I ?in complete English translation
A Neiv Method
in the Theory of
SUPERCONDUCTIVITY
BY N. N. BOGOLILIBOV
V. V. TOLMACNEV
AND D. V. SHIM=
IN THIS unprecedented complete solution
to tlie ? perplexing problem of con-
structink 'a microscopic theory of super-
conductivity, the authors explain their
new method?a .result of the research of .
N. N. Bogoliubov and V. V. Tolinachev?. -
based on a physical and r mathematical
analogy with supeffluidity.
Here they give calculations for the en-
ergy of the superconducting ground
state using Frohlich's Hamiltonian, as
well as-of the one-fermiou and collec-
tive elementary -excited states; they --
provide a detailed analysis ,of the role
of eke Coulomb interaction between,
the electrons in the theory of 8up6.con-
ductivity; and demonstrate how a sys-
tem of fermions' is treated with a
fourth-o-rder interaction Hamiltonian
and establish the critek-on for its su-
perconductivity ? all of -which is indi-
cated in greater detail in. the -complete
table of contents shown to the right.
? cloth bound ? 130 pages ? $5.75
_
r---- Complete Table of Contents
- -
- INTRODUCTION
outline- of the present state of superconductivity
theory ? -brief description of the microscopic
theory of superconductivity ,
"
- FROHLICH, S MODEL OF
SUPERCONDUCMITY
principle of compensation of "dangerous" dia-
grams ? analysis of the compensation equation
? the ground state' and the one-fermion excited
states
RENORMALIZED THEORY OF
SUPERCONDUCTIVITY IN
rnolarces mom.
compensation and renormalization equations ?
simplification-of the relations obtained ? energy
difference between normal.and- superconduct-
ing states ? the property of superconductivity
.SPECTRUM OF
COLLECTIVE EXCITATIONS IN
THE SUPERCONDUCTING STATE
the method of approximate second quantization
aeapplied to a system with Coulomb interaction
? collective excitations in Frohlich's model ?
solution of the secular equationi?longitudinal
- .
excitations ? solation .of the seculavequations?
_
transverse excitations
INCLUSION OF THE COULOMB
INTERACTION BETWEEN ELECTRONS
staiement of the problem ? compensation and
?
rehormalization Conditions ? transition to the
"time-dependent" formalism ? final form of the
compensation equation for the electron dia-
grams ? energies 'of the ..groUnd state of the
one-fermion excited state ? transformation of -
the Q (k; k') kernel ? finding X-, it, and (Al ? a
related model-
QUALITATIVE DESCRIPTION OF
? EFFECTS DUE TO
THE COULOMB INTERACTION ,
approximate determination of the renormalized
tri)cmd "g ? the properties of Qc and Qph ? gen-
eral properties of- the basic compensation
equation
FERMI SYSTEMS WITH
WEAK INTERACTION
formulation-of the BCS theory ? compensation
equations ? collective excitations ? influence
of ttie Coulomb interaction
CONCLUSION
the thermodynamics and electrodynamics of
the superconducting state -? a qualitative. pic-
ture of the phenomenon of auperconductivity '
APPENDICES
on the question of superfluiditi In nuclear mat-'
tor ? on a variational principle in the many-
body problem _ `. .
CB translations by bilingual scientists in-
clude all diagrammatic, photographic and
tabular material integral with the text.
CONSULTANTS IBUREAW- INC.
, 227 WEST 17TH STREET, NEW YORK 11. N. Y
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vol. 4, no. 6
June, 1958
THE SOVIET JOURNAL OF
ATOMIC ENERGY
ATOMNAIA ENERGIIA
A publication of the Academy of Sciences of the USSR
Annual Subscription $75.00
Single Issue 20.00
Year and issue of first translation:
volume 1 number 1 january 1956
TRANSLATED FROM RUSSIAN
Copyright 1059
CONSULTANTS BUREAU, INC.
227 W. 17th St., NEW YORK II, N.Y.
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EDITORIAL BOARD
OF
ATOMNAIA ENERGIIA
A. L Alikhanov, A. A. Bochvar, V. S. Emerianov, V. S. Fursov,
V. F. Kalinin, G. V. Kurdiumov, A. V. Lebedinskii, I.I.Novikov
(Editor-in-Chief),V.V.Semenov (Executive Secretary),V.I.Veksler,
A. P. Vinogradov, N. A. Vlasov ( Assistant Editor-in-Chief).
Printed in the United Staten
Note: The sale of photostatic copies of any portion of
this copyright translation is expressly prohibited by the
copyright owners. A complete copy of any article in the
issue may be purchased from the publisher for $12.50.
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SOVIET JOURNAL OF ATOMIC ENERGY
Volume 4, Number 6 June 1956
CONTENTS
The Investigation of the Transitional Acceleration Stage in a Synchrotron with a
Betatron Initial Stage. I. S. Danilkin and V. E. Pisarev
PAGE
659
669
RUSS.
PAGE
503
510
Effective Boundary Conditions in the Theory of Neutron Diffusion. G. A. Bat and
D. F. Zaretskii
Resonance Absorption of Neutrons in an Infinite Homogeneous Medium. G. I. Marchuk
and F. F. Mikhailus
683
520
Mutual Screening of Blocks of Resonance Neutron Absorber in a "Tight" Lattice.
V. V. Orlov
699
531
The Energy Distribution of Neutrons from a Pulsed Source in a Moderator with a
Constant Mean Free Path M. V. Kazarnovskii
709
539
Investigation of the Statistical Distribution of Spontaneous U 8 Fission Acts According
to the Energies of the Two Fragments. B. S. Kovrigin and K. A. Petrzhak
721
547
Recrystallization of Uranium by the Action of Cyclic Heat- Treatment. A. A. Bochvar,
729
555
G. I. Tomson, and N. T. Chebotarev
Tissue Doses of Fast and Ultra-Fast Neutrons. M. I. Shal'nov
735
557
Silicon Photocells as Solar-Radiation Converters. V. S. Vavilov, G. N. Galkin, and
V. M. Malovetskaia
751
571
Radioactive Carbon From Nuclear. Explosion and Nonthreshold Biological Effects.
A. D. Sakharov
757
576
Letters to the Editor
The First Discovery of Coffinite in the USSR. Ia. S. Filipenko
763
. 581
The Light Isotopes of Tellurium. M. Ia. Kuznetsova, V. N. Mekhedov, V. N. Rybakov,
766
583
and V. A. Khalkin
Measurement of 8-Activity in an End Counter. N. E. Tsvetaeva and M. N.
Brusentsova
767
583
Dosimetry Nomogram for Determining Working Time in a Mixed Radiation Field.
G. M. Obaturov
770
585
Scientific and Technical News
On the Present State of the Problem of Accelerating Atomic Particles (773). 7-Bev
and 12.5-Bev Synchrocyclotrons (774). A Single-Dee Cyclotron (776). A 1-Bev
' Synchrotron in Italy (778). Measurements of Thermal Neutron Spectrum in a Swedish
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CONTENTS (continued)
RUSS.
PAGE PAGE
D20 Reactor R1 (779). Engineering Test Reactor (ETR) (780). The American
Boiling- Water Reactor VBWR (784). Fluoride Fuel for High-Temperature Reactors
(788). Extraction of Uranium from Spent Nuclear Fuel by Dissolving in Fused Salt
and Fluorination (793). Ion Exchange Behavior and Dissociation Constants of EDTA
Complexes of Americium, Curium, and Californium (794). Use of Radioactive
Isotopes in Metallurgical Investigations (795). Development of Uranium Mining in
Canada During 1957 (796).
Brief Communications
'798
605
Bibliography
E. Teller and A. L. Latter, Our Nuclear Future . ? . . facts, dangers, and
opportunities. Criterion Books, New York, 1958
801
608
The Polish Journal "Nukleonika" (Nucleonics)
805
610
Recent Literature
806
611
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THE INVESTIGATION OF THE, TRANSITIONAL ACCELERATION STAGE IN A
SYNCHROTRON WITH A BETATRON INITIAL STAGE
I. S. ,Danilkin and V. E. Pisarev
This paper is devoted to an application of the theory of the transition stage (the process
of transition from betatron to synchrotron acceleration) to the FIAN 250 Mev synchrotron for
the case when the accelerating field is established adiabatically. From the experiments and
calculations that have been carried out it is possible to judge the correctness of the theory as
applied to accelerators of this type. Some characteristics of the electron beam during the
betatron stage, for example, the electron energy distribution, have been obtained from the
experimental data.
It is also shown that it is possible to use the dependence of the accelerated-particle
beam intensity on the amplitude of the accelerating potential to determine the voltage am-
plitude at the resonant cavity.
By the transition stage in synchrotrons with an initial betatron stage we usually mean the combination of
processes associated with the capture of the electron beam into the synchrotron acceleration conditions after a
preliminary acceleration during the betatron stage. Because of the relative simplicity of the theory of the transi-
tion stage it is possible, as will be shown below, to verify the correctness of the theory itself, to analyze the ex-
perimental features of this acceleration stage, and to determine a number of characteristics of the particle beam
captured into the synchrotron stage.
The present paper is devoted to an analysis of experiments on the transition stage of synchrotron operation.
The experimental part of the work was carried otit.during 1951-1952 at the FIAN 250 Mev synchrotron [1J. A
detailed description of this accelerator is given in [2].
The Theoretical Investigation of the Transition Stage
The theory which was used in carrying out the calculations has been developed in a series of papers [3-5]*
and therefore here we will only present the main arguments and the results obtained.
As is known [3, 4], the phase motion of a particle after the accelerating electric field is switched on is
described by the equation:
d Es dcp eV()
d?t oK dt 27c COs cp =
(1)
where ip is the phase angle of the electron, Es and Ws are the total energy and angular velocity of rotation of
an equilibrium electron, V(t) is the amplitude of the accelerating electric field, evs the average fractional
1
increment of the electron energy during one revolution, and K =1 + ? (n is the exponent describing
? Reference [5] deals with the experimental verification of the theory presented in [4]. It must be pointed out,
however, that this work differs completely from our own in scope, aims, and experimental conditions.
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the rate of fall of the field, 3 is the ratio of the particle velocity to that of light c).
V (t), the amplitude of the accelerating field, is usually a function which increases_monotonically from
zero, such that fort? to > T , V (t) Rt Vin = constant. The timet is measured from the instant when the value
of the magnetic field intensity passes through zero (the start of the betatron acceleration cycle), to denotes the
instant when the accelerating field is switched on, while 7- is the time interval during which it is established.
Taking into account that usually in the interval T. Es ctc constant, we obtain by integrating (1):
p2p? 2ko s(p? cp0)? 2kV (sin cp ? sin ?),
sin p= sin ? dV , k = e EK .
0
(2)
Thus, instead of the integration constant G (po,cpo) = 5)(2,-+ 2kv9cp0 ? 2kVsincp0, which determines the phase
trajectory for the case V = constant, we have for V = V (t)
G (yo, cp.o, t) 2kt8p0 ? 2kV (t) sin?. (3)
Comparing (2) with the equation of the curve which determines the boundary of the region of stability:
cp2 = 2kV (t) [sin ? + sin ?. ? (? + co.) cos cp.],
Os
cos ?. = ,
v .
we find the condition governing the capture of particles into the region of stability at time t :
G (po? 27cn, 1) ?kV (t) [sin Ts c" Y3],
n --- 0, +1, ? 2. .. ,
? (Ps< To 0) and putting
(t) dt
(t)
we can write Expression (9) in its final form:
664
WI31 c?013,
1,02 ws
2TcR, (1?n) E's (t) '
t'
ip (t) + 'a (01.
' ??
1,01 (Ds %
? ?
. aj5 Gos
WA An>ftzez
411V: V.Z.Z7Zrzzil
s-cpos
\?)
0,9,9
0,98w
ws
250 t 300
350 400
t, ?sec
Fig. 4. The variation of the equilibrium angular frequency of the
captured electrons w and the synchrotron frequency cos with time
during the transition stage.
The curves (08 ipoa and cq
, os give the frequency spread in
the betatron beam being captured and the allowed frequency spread.
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(th
(12)
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The frequency region occupied by the electron beam as a function of time is bounded in Fig. 4 by the
curva (08 (t) ip 08(0.
It is obvious that a partial or complete capture of electrons into the synchrotron stage of acceleration is
possible only for that interval of switching-on time where the frequency region cos ? ipo8 occupied by the
betatron beam at the time t = to when the accelerating field is switched on, overlaps partially or completely
the region of the allowed initial conditions cos ? ZPos ? Introducing the function (F), the distribution of
electrons across the radial width of the beam p = FAR, where AR is the total radial width of the beam, while
for definiteness p is measured from the inner edge of the electron beam, we find that
a (to)
.1 (to)
I)
0
(13)
Here a (t)w (t) [ ?640 (01 is the frequency interval which corresponds, for a chosen t , to the common ordinate
apoo (t)
in the intersecting regions bounded by the curves cos ? c?Pos and cos ? (P08 (Fig. 4)] and the variable of inte-
gration is ?0) (A0) is measured from the lower end of the interval
20(t)
The function a (t) calculated for our equipment (Fig. 3) represents the function J(to)_for the case when
the electrons are distributed uniformly along the radius Lqs(F) = constant]. The two end points of the function
describing the beam intensity of the accelerated particles are determined by the obvious relations
(t) 1" P0,3 (1) = (1)3 Pos (t),
(1) ? (Poi3 (1) = (P.oi (t)
and are independent of the form of the distribution function ir (F).
The Distribution of the Instantaneous Equilibrium Orbits of the Electrons During
the Betatron Acceleration Stage. Comparison of the Experimental Results
'and the Theory of the Transition Stage -
From Expression (13), which gives the beam intensity of the accelerated particles as a function of the time
at which the accelerating field is switched on, we can easily calculate the distribution of the radii of the instan-
taneous equilibrium orbits ir (F) for the electrons in the betatron beam. In fact, from (13) it follows that
dJ ft? dJ dto
= d10 d
where F is the value of F corresponding to A co. Since in our case 8 sts 1 and consequently
(14)
dt
then approximately F = a, Therefore, in order to determine --IL- we can use directly the curve a (t) given
df
dJ (to)
in Fig. 3. The quantity dto is found by differentiating the function J(to), given in the same figure.
The function it (F) calculated in this way is shown in Fig. 5.
Finally, converting with the help of the well-known relation
11(t)
AR (t) = AR (to) if (t)
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the radial dimensions of the betatron beam to the start of the betatron acceleration stage, we find that at the
instant of injection pRi = 7 cm. Comparing this value with the dimensions of the working region of the chamber
(6.25 cm) we conclude that in the equipment investigated the capture into the betatron acceleration stage takes
(F)
1,0
0,5
0 0,1 02 03 0,4 05 06 0,7 0,8 09 1,0 F
Fig. 5. The distribution function of the electron
equilibrium orbits at the beginning of capture into
the synchrotron acceleration stage.
(t), aria. units
1,o
0
270
place over a wide range of positions of the instantaneous
equilibrium orbits in the space between the chamber
center and the injector and target and that capture is
predominantly into the central orbits (the distribution
function 4, (F) is independent of the time if, the loss of
particles during the acceleration stage is neglected).
In order to verify the correctness of the distribution
of the instantaneous equilibrium orbits that was obtained,
the functions (to) and J (V), the beam intensity of the
accelerated particles as a function of the accelerating
electric-field amplitude, were calculated for other values
of the equipment parameters; the function J(V) is also
dependent on
(v)
where F (y) can be easily found with the help of the
adiabatic invariants and the capture Condition (7b) in a
way which is completely analogous to the method used
above.
.280 290 300 310
a)
320 330
t, ti sec
J(), arb. units
1,0
0,5
0
1
?
360 370 360
tjLsec
Fig. 6. Comparison of the calculated and experimental functions J(t) for two operating
conditions of the accelerator. a) Vm = 681 v, Xs = 5.1 m; b) Vm RI 680 v, Xs = 4.94 m;
- - - - ) calculated curves; ? ) experimental curves.
The results of the calculations of the functions (to) and J (V) on the basis of the distribution function 4, (F)
(Fig. 5) and the experimentally determined curves are given in Fig. 6. The agreement between the experimental
and the theoretical curves is very satisfactory.
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Further, an indirect confirmation of the theory of the transition stage is the agreement of the limiting
points on the initial function J (to) (Fig. 3), since the dimensions of the betatron beam determining this coin-
cidence were found from independent experiments which correspond to the function J(Vm) (Fig. 2).
SUMMARY
The calculations and experiments that have been carried out lead to the conclusion that the theory of the
transition stage for synchrotrons with a betatron initial stage is sufficiently adequate when the accelerating field
is established adiabatically Relation (7b)L Using the theory of the transition stage, we are able to develop
the methods for the indirect investigation of the betatron stage, to obtain a number of functions [*(F). AR]
characterizing the capture of the electron beam, and on the basis of the experimental data obtained to study
some of the features of the capture of particles into the betatron stage of acceleration.
In addition to this, the investigation of the transition stage leads to a deeper understanding of the operation
of the accelerator and makes it possible for us to determine some of its parameters (for example, the effective
amplitude of the resonant-cavity electric field) when the determination of these parameters by another method
is associated with difficulties of some kind.
The authors express their gratitude to M. S. Rabinovich for his advice on numerous occasions and for fruit-
ful discussions.
. LITERATURE CITED
[1] V. E. Pisarev, Thesis (In Russian] (FIAN SSSR, 1954).
'[2] A. Ia. Beliak, V. I. Veksler, V. N. Kanunnikov, P. A. Cherenkov, and B. N. Iablokov, Supplement
No. 4 to J. Atomic Energy (USSR) (1957), p. 57. *
[3] M. S. kabinovich, Thesis [In Russian] (FLAN SSSR, 1948).
[4] T. R. Kaiser, Proc. Phys. Soc. 63A, 52 (1950).
[5] T. R. Kaiser and J. L. Tuck, Proc. Phys. Soc. 63A, 67 (1950).
Received September 27, 1957
? Original Russian pagination. See C. B. Translation.
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EFFECTIVE BOUNDARY CONDITIONS IN THE THEORY OF
NEUTRON DIFFUSION
(Survey)
G. A. Bat' and D. F. Zaretskii
In this review, a method of determining effective boundary conditions (EBC) is described
which guarantees the asymptotic agreement of the solution of the neutron diffusion equation
with the solution of the corresponding kinetic equation. For monoenergetic neutrons, the EBC
are considered for plane and cylindrical surfaces of "black' and "gray" bodies. Results are
given for the EBC for the case of cylinders of arbitrary section.
The authors discuss the simplest problem in the determination of EBC for neutrons that
are slowed-down in a medium with heavy atoms and with n energy-independent cross section.
The review gives also results obtained by various authors in the USSR and in other countries.
INTRODUCTION
In the great majority of cases, the critical dimensions of nuclear reactors are determined by solving a
system of spatial differential equations (diffusion equations) for the neutron density. Thereby, it is necessary that
boundary conditions be given on the surface of the control-rod system guaranteeing the absorption of neutrons of
various energies. However, in the neighborhood of bodies which strongly absorb neutrons, the conditions of appli-
cability of the diffusion equations are violated. The diffusion equations may be "adjusted" by introducing boundary
conditions which have the property that in a region far from the absorbing surfaces, the solution of the diffusion
equation agrees with the exact solution.
The boundary conditions for the neutron density guaranteeing agreement in the asymptotic region of the
solution of the diffusion equation with the solution of the kinetic equation are ordinarily called effective boundary
conditions (EBC).
In order to find the EBC, it is necessary to consider either the kinetic equation for the neutron distribution
function with respect to space, flight directions and energies or the integral equation for the neutron density, the
zeroth moment of the distribution function.
Let us observe that the application of the diffusion equation to strongly absorbing media requires the in-
troduction not only of EBC but also of effective diffusion coefficients and effective neutron sources [1].
We shall limit consideration to the case of greatest practical interest of rods in weakly absorbing media.
The effective diffusion coefficient will be written in the form D = ?1 taking the velocity and mean free path
3
of the neutrons to be equal to unity.
A body will be called "black" or "gray" depending on whether it completely or partially absorbs the neutrons
incident on its surface. Ordinarily the EBC are given in the form of a logarithmic derivative of the asymptotic
neutron density as at the surface S of the absorbing rod:
d ln nas (r)
dv
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where v is the direction of the outward normal to the surface of the absorber. Another widely used form of the
EBC is the prescription of a surface upon which nas (r) vanishes. There are then introduced, for example, an
effective rod radius raj- and an extrapolation length zo for the case of a plane boundary between the medium
and the vacuum.
The usual conditions for the absorbing rods in reactors are such that the density of neutron sources may be
assumed to be uniform. However, the problem of determining the EBC is often facilitated if one assumes that
there are no sources in the medium but that a neutron current is given at infinity. From the work of Le Caine
[2J concerning the density of neutrons near the plane boundary of a half-infinite medium and vacuum, it follows
that the value of zo for the case of a uniform distribution of sources differs only slightly from that for the case
of a neutron current incident from infinity. Therefore, we may assume that for our conditions the choice of the
source distribution does not influence the EBC.
We present below a review of various methods of determining the EBC along with the results obtained by
these methods. In the majority of cases, the further development of the ideas involved and of the nature of the
calculational methods is possible, but is very cumbersome.
The generality and effectiveness of the methods developed make them an important part of the theory of
kinetic equations.
Monoenergetic Neutrons
1. The simplest determination of the EBC is for the case of an infinitely thin black rod (filamentary
sink) in a medium with a uniform distribution of sources. Such a sink does not violate the isotropy of the neutron
current, and the correct boundary condition
X = Xo = 4/3
is obtained by comparing the unidirectional kinetic and diffusion currents at the rod:
(1)
2. The other limiting case of a plane dividing boundary between the medium and vacuum is considerably
more complicated and has been considered by two methods.
Exact (analytical) method of Wiener- Hopf [3]. The starting point is the Boltzmann equation for he
neutron distribution function with respect to space (z) and direction of flight (G) in sourceless media: .
SF('5-2)1 (z, d4(17: ,
sa
(2)
where f(z, (d)dzd) is the number of neutrons in an element of volume in the neighborhood of a point z for
velocities in an element of solid angle dQ, and F (C1',0) is the scattering indicatrix (the probability that the
neutron changes the direction of its velocity from CZ' to as a result of collision). For the case of isotropic (in
the laboratory system) scattering, F((1', ) = 1 and Equation (2) has the form
(z, p.)
+ (z, ti) = n (z),
11 az
(3)
where u is the cosine of the angle between the direction of flight of the neutrons and the normal to the surface
of the dividing plane, n (z) is the neutron density ("zeroth moment" of the distribution function):
+1
n (z) = f (z, 11) (ht.
?t
Taking the Laplace transform of (3) and using the notation
CO
(I) (s, e-sz f (z, dz,
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we obtain
C 0
(I) 0 (s) =e-sz (z) dz,
1)(s, 19 EA)0 (s)I2 v.! (0, IL)
(
? 1- F st.).
Integrating (5) with respect to ? between the limits - 1 and + 1, we find that*
0
'I) (s) (i v arc th s ) _ C i.tf (0, v.) 7
? ?'-'s all? ,
? ?. s 3 1 + sp.
-t
(5)
(6)
The basis of the method of Wiener- Hopf is the fact that Equation (6), with the help of a theorem of Liouville
[4], can be brought to the form
(Do (s)
2 2
% ? s
const,
(s)
where X (s) is a known regular function, ? K are the principal roots of the equation
v
arc th
==1.
The inverse Laplace transform reduces to the calculation of residues at the points s = ? tc
We obtain as a result that in a region far from the boundary
nas (z) sh (z zo),
where the extrapolation length zo is determined by the expression [2]
For
zo (Es)
[ 1 p.2 (1-E5)] are th 2 dv.
jj (1 ? 1.1.2 ) [1?Esp. arc thp.12+
zo (Es) 1/Es + (In Es)/2 - (In 2)/2 ( L's In 2)/2,
(7)
(8)
(9)
zo (1) =0,7104...
Variational Method [2, 5], The kinetic Equation (3) with boundary conditions may be reduced to the in-
tegral equations of Peierls for the neutron density (this equation may also be obtained directly from physical con-
siderations):
where
-
n (z) =S n (z' ) (J z - z' I ) dz',
2
0
co
e-xt
(13)
The basis of the variational method is the fact that for an inhomogeneous integral equation with a symmetric
kernel [K(z, z') = K (z', z)J with
? `th' 'tanh', 'sh' 'sinh'; 'ch' 'cosh'; 'tg' 'tan' - Publisher.
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q(Z)_ q (z' ) K (z , z' ) dz' h (z)
the functional
q (z) [q (z)-5q(z' ) K (z, dz'i dz
F (q) -
[ S h (z) (z) dzi2
has a minimum and equals [ S h (z) q (z) d z -1 , when q(z) is a solution of Equation (14).
In order to reduce (12) to the form (14), Le Caine used the two expressions
n (z) [sh x (z zo) (z)]
and
e"0
it (z) = k1 [e+q2 (z)] -2- .
??? K Z
The simplest trial function 72(z) = e in (17) yields
1 , -IF ln(1+%)]2- - 41.
1101n2(1-7.2)
zo -
1 1 ) ?
Li-
ln (1 -%2)
%2
TABLE 1
Values of Es zo
Formula for
z
?4
41
8 4-4
q11-.1
?
n
z
E
Cd.
E
1,0
0,7104
0,7104
0,7083
0,7104
0,9
0,7106
0,7106
0,7095
0,7091
0,8
0,7113
0,7113
0,7105
0,7091
0,7
0,7127
0,7127
0,7121
0,7140
0,6
0,7154
0,7154
0,7150
0,7318
0,5
0,721
0,7204
0,7202
0,7792
0,4
0,730
0,7300
0,7298
0,3
0,749
0,7484
0,7484
0,2
0,785
0,7847
0,7848
0,1
0,850
.0,8539
0,8538
0,0
1,0
'1,000
1,000
? Values of Eszo*.
(14)
(15)
(16)
(17)
(18)
The results of the calculation of zo according
to Formulas (10), (18), as well as Formula (24) of [2],
which was obtained by using a more complicated
trial function i(z), are given in Table 1. Note that
down to Es Ec, z0 = 0.71/E5 with good accuracy.
In the last column of the table are entered the
extrapolation lengths for the case of a uniform dis-
tribution of sources:
z: Zo+ 1 111 Es 1/-(1 -Es) (x2-1+Es). (19)
2(1__2)
It is evident from the table that zo* begins to
differ appreciably from zo only when Es = 0.5 = Zc.
3. Of primary importance for the calculation of
the efficiency of reactor regulators are the EBC at the
surface of a black, circular cylinder. We describe
below the basic methods of solution of this problem.
Equilibrium method. On the basis of neutron
equilibrium, A. Brudno (1951) found EBC for a black
cylinder of arbitrary radius ro located in a nonabsorbing medium with isotropic scattering for the case of a current
incident from infinity. This method is very simple and guarantees sufficient accuracy.
The normal component of the kinetic current at the point r is given by the expression
,--R
P (r) n (r' ) oS cp d V, ( 20)
where R is the distance between the points r and r', cp is the angle between R and r and the integration is carried
out over the region 'V not "screened" by the rod (that is, the largest region such that a straight line between the
point r and any point r' of the region does not touch the rod).
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The neutron density may be determined from the Peierls equation
n (r) =Sc n (r) 8
4TC R2
V
At a great distance from the rod, the density is given by the expression
tias (0= X + r?r
o
In the asymptotic region, the current through an arbitrary surface coincides with the diffusion current:
1
P (w) = ?3 ?
(21)
(22)
Since, by hypothesis, the medium is nonabsorbing, this same current passes through an arbitrary surface
surrounding the rod. In particular, P(rd= ?1
3 ?
We may also approximate P(ro) by substituting (22) into the right-hand side of Expression (20). We then
obtain x as a function of ro:
where
4
X (re) = ?3 - roR (re),
R (re) = [Ki(x) - K i(x)I x p ndx ,
0
p,(1) =- 1 +I t - (4- - t) arc tg t +in (1+t2),
K (x) = K (y) dy
(Ko and Ki are MacDonald functions).
From (23) it follows that X (re) xo = 4/3 for ro->
differs somewhat from the exact value x (co) = zo =0.7104.
rods may be diminished by using the interpolation formula
1.2
1,0
0,8
(23)
0 and x (ro) = 2/3 for ro ?> co. The last value
The error in the determination of x(ro) for thick
9
0,7104
X* (ro) = X (re) ?3 [43 X (re)] ?
2
3
0.5 0
0.5 1,5 1 25 3 7,0 3,5
Fig. 1. EBC for black cylinders. 1) Equilibrium method;
2) expansion for small 4; 3) expansion for large ro; 4)
P3 approximation of variational method: 0) numerical
solution.
( 2 4)
The result of the calculation is given in
Fig. 1.
Numerical solution. In 1951, S. Sobolev,
A. Brudno, M. Lavrova, G. Mukhina, and V. Khodakov
by means of a direct numerical solution established
the reference point value x (1)=0.889 i 1%. A
grid method of solution was used. The agreement
of the above-mentioned results of Brudno with the
exact numerical solution is completely satisfactory.
Variational method [6]. As in the case of
the direct numerical solution, the variational
method gives extremely reliable results. Just as in
the problem of the half-space, the Peierls equation
leads to the inhomogeneous equation
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n 1. + q (r),
(25)
where q (r)---> bin r, and the functional form (15) is used. The condition of the conservation in a nonabsorbing
T?>00
medium of the current through an arbitrary surface surrounding the rod leads to the integral relation
b = ? 3 q (r) Ii (r) r dr ? 3 rh (r) dr. (26)
ro ro
The choice of a trial function in the form q (r) = b in r permits one to find rather easily the quantity
Sq (r) It (r) r dr, and therefore also the quantity b which is connected with the boundary condition by the
ro
relation
1 + b ln
X (r0)= biro . (27)
17
The variational method gives extremely small errors. For example, x equals ? for r0?, oo [5] and 0.99
24
for ro = 0.5.
Method of spherical harmonics. As far as we know, the method of spherical harmonics for obtaining EBC
on the surface of a black rod was first used by Galanin in 1947. Results of calculations with this method are given
also in an article of Davison [7].
The kinetic equation of the type of Formula (2) is expanded in Legendre polynomials and leads to an infinite'
system of differential equations with respect to the angular moments fn(r) of the distribution function ,f(r, ). This
system is "truncated" by assuming that starting with a certain n all fn (r) =0. If we assume that all moments
beginning with the second are zero, then we obtain the P1 approximation (diffusion approximation); if all moments
are zero beginning with the fourth, we have the Pg approximation, and so forth.
We see from Fig. 1 that for thin rods (r0 < 1), the method of spherical harmonics leads to appreciable error
2
(? instead of ?4 for ro 0). The poor convergence of the method for small ro is connected with the fact that
3 3
the neutron density is approximated to the asymptotic density not at the distance 1/; but at the smaller distance
ro. This leads to such a large rate of change of the neutron density in the neighborhood of the rod that the density
may no longer be described by only a few of the moments fn(r).
Solution of the Peierls equation for large and small ro [7]. The Peierls equation for a black cylinder in
a nonabsorbing, isotropically scattering medium may be written in the form
where
00
n (r) n (r') K (r, 7-0) dr' (r >r,),
K (r, r', 7.0) =
(r2-4)1/24-(r,2-71)1/2
IC (p) dp
p2 (r_r,)211/2{(r+712_0}1/2,
r?r' I
p is the distance between the points r and r' in the plane z =0,
2 ? r2?r,2_ 2rr' cos a.
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(28)
(29)
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In order to determine EBC for ro 1
? In the Russian edition of the handbook, Table 44 is incorrectly reproduced. [The page references here are to
the Russian edition - Publisher.]
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(g is the average logarithmic energy loss) an expansion is used which corresponds to the age theory approximation
for the slowing-down process:
(p r) _ aq, (u,
du ?
(56)
This expansion is substituted into an equation of the Peierls type for the distribution of neutrons from a mono-
energetic source a (E E0) f (r):
1
(E, 47z (1_0 S dr (E', r') x
e He?r1
(E -ED) cir,f(i.,) r, 12
X irrc r?
nvEs,
Es =-- CODSL.
For the function p(u, r) =4 (it, r) we obtain the equation
1_
p (u, r) (u., r') r dr' ?
e-e +
1 S au (n, r')r? r'Ir r'l d
4rc
i") dr'.
I()ir ?r' 12
(57)
(58)
If we take the Laplace transform with respect to u, it is not difficult to see that the equation for the Laplace
transform F r) is equivalent to the Peierls equation for monoenergetic neutrons in a medium with absorption.
The parameter of the Laplace transform plays the part of the macroscopic absorption cross section.
F r) r?r112
-T-- F (71, r') dr' +
ITC I
1
7-- (r') dr'.
I r?r' 12
(59)
The determination of the EBC in the region of large slowing-down (u >> 1) requires the knowledge of the
expansion of F , r) for small "absorptions" n. For the geometry of a plane, such an expansion may be found
exactly. In cases of spherical or cylindrical symmetry, it is necessary to use an approximate method (for example,
the variational method). However, it may be shown that under the assumptions that have been made, independently
of the geometry, the EBC for neutrons that are slowing down coincide with the EBC for monoenergetic neutrons in a
medium with weak absorption.
In the case of variable Es(u), the problem of taking into account the effect of the slowing-down process in the
determination of the EBC has not yet been solved. We mention only the following considerations. Ordinarily, for
reactor calculations a multiple group method is used in which a system of one-velocity equations is considered. If
in the equation for the i-th group, the term making this equation inhomogeneous (due to sources) does not change
too rapidly in the neighborhood of the rod, then the results of section 2 may be used. A smooth change of the source
density means that this change must be small over the distance where the neutron density differs from its asymptotic
value. Thus, the use of the monoenergetic EBC for each group is justified, at any rate, for thin rods (r0 > u, then the first of Equations (20) will have the following form:
4)- (12) = A (a) c -(u') g (u', u) da'.
(20c)
The equation determining the probability for a neutron of lethargy u to escape resonance absorption during
the process of slowing down to thermal energy has an analogous form. This equation was first obtained by
Zel'dovich and Khariton [4.).
3. Numerical Method for the Solution of the Slowing-Down Equation
Let us proceed to find the collision density is (u). With this in mind, we will use Equation (16) with the
function A (u) given by Relations (11) and (12). Since the neutrons from the source have an energy considerably
greater than the resonance energy, the asymptotic value of the collision density will be established in the vicinity
of E 0.
If we note that in this energy region absorption is still small, we can use Equation (10), obtained with the
help of the "Greuling-Goertzel approximation" to obtain (u) for u1-c u .su0, where u0 is determined from the
inequality A (u0) ? 1 and tit is the lethargy corresponding to the energy of the source. Thus, for all values of
the lethargy u, we find the function tp (u) from the equations for the one-component moderator:
For slowing down in a mixture:
4)(0 = 1_ a
I A (u')4) (u') du' ,
u;--q
if u 0 u uas,
S1- A(u')
4 A(u') {-e [1? A(u'
X e usource
if usource 5- u :5110.
du,
r
(a) ? -u')A, (il) 4, (re) du' --I-
1
e-(u-u') A2(u')4)(u')du' ,
?a2
if u0 5. u uas,
(21)
(22)
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4) (1) t A (u) + 6 [1?A (u)J' X
IL
- 1 -A(u')
p ? -A(u')+E tl- A (u") Jdu'
X e source
if nsource Is Is 110,
where I and are averages over the components of the mixture and A (u) = A1(u) + A2(u).
For the solution of the first of Equations (21) we will use the following numerical method. Let us introduce'
the function 99(u) = (u) en and rewrite the integral with the help of a quadrature formula having equal steps h:
pfl=IB j+ an,
1=n-it
vwhere ? = (ih), Ai = A (ih), k = 6 is the quadrature error, = h , and uh is the coefficient
h n 1- a
in the quadrature formula.
For 99n we obtain the computational formula
i=n-h
1? pA,
(49r1= Vk + An, An is the error in the value of yon), using which we are able to calculate (u) for any values
of u from the known values of (pi (i= n- k, n- k + 1 n- 1).
Similarly, for the case of slowing down in a mixture we obtain from (22)
(23)
?It =
n - n
ACpj,
i-= 71-10 71. -112
1-131/6 ?-
+ An.
(24)
If q2 is not an integral multiple of h, then a correction factor should be introduced on the right-hand side of (24)
to take into account the integral over the region q2- k2h.
4. Numerical Method for the Solution of the Adjoint Equation
We now proceed to the solution of the adjoint equation.
From the first equation of System (20), using a method analogous to that used for the solution of the basic
problem, let us find numerically the adjoint collision density of neutrons.
For the case of a one-component medium, Equation (20) will have the form
,u
A (a)
4)* (io du'
1? a
e-(4,-u)
+ A (u) ,
if nas- q < < lias?
Next, let us introduce the function cp* (u) r(-) e- . Then Equation (25) will take the form
A (u)
u a-;
1 -u
p* (u)
1? a 1? a ?
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The solution of this equation is found with the help of differentiation. It is easy to show that in the interval
uas?
q < u < uas the solution has the following form:
,4)* (u)=1 (u)
A(u")du" ?it' ?
1
e u
? cc
du'i.
t
A( u')du'
(26)
For values of 4)* (u) outside this interval, ? (u) is calculated with the help of quadrature formulas (see above):
(3 A icet
+1
? l--(3i1n 'a'"'
For slowing down in a two-component mixture the first equation of System (20) can be written as
it as ua,
(U)A 1(u) (1.1') cht -4- (Oda' +
1? al
(27)
1?al 1?a.
..
+ e-. i aillt (U) + a2A2 (U) 1 (28)
for uas? q < u < uas (s is the smallest of the numbers.% and q0. Here cp ? (u) = tp ? (u) e1. Introducing a new
function
0* (u) _y* (u)? F (u)
where
P (u) ? A1 (u) A2 (u)
I ?a, I ?a2
F (a)la Ai (u) a2A2 (u)1
P (u) d- [
? 1 ?a2 '
and differentiating the equation obtained, we can write the adjoint collision density for the interval uas? q < u <
< uas in the following form:
uas
S P(u')du'
(I)* (U) P (u)e u
uas
? S P(u)du
S (u') e du' F (u).
X
From this equation 6o ? (u) can be calculated for the interval
uas q2 < a < uas
For these values of the lethargy the equation can be written as follows:
u +q
4
Ai (u.)
cp
? * (u') du' ?
a,
(29)
(30)
ua, -u
e as ?ae-u
+ A2(u) ? (u')duf 112(u)
I ?aa
?
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Applying to this equation the method of numerical integration described above, we get
cp* (lin) =
n-Flq m?un
t31A1 (un) E 0. The method leads to a system of algebraic equations
analogous to (A.11) if n 1, or to a system of differential equations of order n? 1 if n > 1.
LITERATURE CITED
[1] L. S. Ornstein and G. E. Uhlenbeck, Physica 4, 478 (1937).
[2] 0, Olsson,_ Arkiv fys. 10, 129 (1956).
[3] M. Demeur, A. Gribaumont, and P. Jansens, Bull. cl. . Sci. Acad. roy. Belgique 40, 526 (1954).
[4] G. Placzek, Manhattan Project Report A-25 (Quoted in Reference [5]).
[5] R. E. Marshak, Rev. Mod. Phys. 19, 185 (1947).
[6] G. F. Dardel, Trans. Roy. Inst. Technol. Stockoln 75, 1 (1954); Phys. Rev. 94, 1272 (1954).
[7] R. Walen, Recueil de traveaux de l'Institute de Rechercher sur la Structure de la Matiere, Belgrad,
(1952).
[8] L. E. Lazareva, E. L. Feinberg, and F. L. Shapiro, J. Expt1.-Theoret. Phys. (USSR) 29, 381 (1955).
[9] A. A. Bergman, A. I. Isakov, I. D. Murin, F. L. Shapiro, I. V. Shtranikh, and M. V. Kazarnovskii,
Physical Research (Reports of the Soviet Delegation at the International Conference on the Peaceful Uses of
Atomic Energy) [In Russian] (Izd. AN SSSR, 1955), p. 57.
[10] A. Akhiezer and I. Pomeranchuk; Some Problems in Nuclear Theory [In Russian] (Gostekhizdat,
Moscow-Leningrad, 1950), 2nd Edition.
Received November 12, 1957.
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INVESTIGATION OF THE STATISTICAL DISTRIBUTION OF SPONTANEOUS
U238 FISSION ACTS ACCORDING TO THE ENERGIES
OF THE TWO FRAGMENTS
B. S. Kovrigin and K. A. Petrzhak
Using an apparatus consisting of a double pulse ionization chamber, two amplifying
channels, a coincidence circuit and a two-beam pulsed oscillograph, we measured the kinetic
energy of each of the two fragments formed during nuclear fission. 780 cases of spontaneous
U238 fission and about 4500 cases of U235 fission by slow neutrons were recorded. Using these
data we plotted the statistical distributions of acts of spontaneous fission and fission with slow
neutrons according to the energies of the two fragments. These distributions gave the following
curves for the two fission methods: a) the energy spectrum of all fragments and that of light
and heavy fragments separately; b) the distribution of acts according to the total kinetic energy
of the two nuclear fragments; c) the distribution of fission fragments according to mass; d)
the relation of the average total kinetic energy of the two fragments to the ratio of their masses;
and e) the relation of the average kinetic energy of light and heavy fragments to their total
kinetic energy. The results of the two methods of fission are quite similar. It was found that
the total kinetic energy of the two fragments in spontaneous U238 fission was, on the average,
4 Mev less than the energy in U235 fission by slow neutrons.
In paper [1] the energy spectrum of the fragments from spontaneous Um fission was investigated and
compared with the spectrum of the fragments from U235 fission by slow neutrons. A qualitative investigation of
the energy spectrum of the fragments from spontaneous Cm2 fission was carried out in work [2]. In paper [3]
the spectra of fragments from spontaneous Pu24? fission were compared with those from Pll239 fission by slow neutrons,
i.e., actually the spectra of fission fragments from the same PO" nucleus in different energy states. The spectra
of fragments from spontaneous fission of heavy nuclei and fission produced by slow neutrons were found to be
extremely similar in form.
The method used in these experiments consisted of measuring the energy of one of the fragments from
each act of fission using a pulse ionization chamber. This method made it possible to investigate the general
form of the energy spectrum of the fragments from spontaneous fission, to determine the most probable energies
of light and heavy groups of fragments, and to find the ratio of the heights of the peaks and the ratio of the height
of the depression to the height of one of the peaks.
However, in several cases the energy of both fragments has been measured simultaneously [4-9] in studying
nuclear fission by slow neutrons,and this makes it possible to obtain much more information on the process of
fission from the distribution of fission cases according to the energies of the two fragments.* The purpose of the
present work was to apply this method to the investigation of spontaneous U238 fission in order to compare directly
the distribution of fission acts according to the energies of the two fragments and the results of this distribution
with the corresponding ones for U235 fission by slow neutrons., Such a comparison could be made using the same
sample of natural uranium, as U235 and U234 contribute little to the rate of spontaneous fission of natural uranium
and practically only U235 participates in fission by slow neutrons.
? When this article had been sent to press, the authors discovered paper [101 on the use of this method for the
comparative study of spontaneous PU242 fission and Pu211 fission by thermal neutrons.
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Apparatus and Experimental Method
Due to the low probability of spontaneous fission (the rate of spontaneous U238 fission is 25 fissions/g ?hr [11])
not less thin 50 mg of uranium had to be used so as to record 700-1000 acts of spontaneous?fission over a period
of 2-3 months and thus obtain an acceptable statistical accuracy for the results. In exact measurements of
fragment energies, an area density of the layer of not greater than 1% of the range was permitted, i.e., 0.25 mm
of air or 0.075 mg/cm2of U308. In order to observe spontaneous fission, we considered an increase of this area
density by a factor of 2 as permissible.
The values determined for the total amount of uranium and its area density indicated that the preparation
should have a working surface of about 500 cm2.
In most papers on the simultaneous measurement of the energy of the two fragments,the fissile layer had a
thin cellulose nitrate or metal backing. The discrepancies in the fragment spectrum caused by the presence of
the backing were considerably reduced by collimating the direction of the fragments. Collimation in our work
would have resulted in a large decrease in the rate of counting. We therefore decided to forego collimation and
prepare a layer without a backing.
The layer prepared was a plate of U308 with an area density of about 0.15 mg/cm2, fixed onto a flat rigid
frame with 600 closely arranged holes of 9 mm diameter. The thin plates of U308 were prepared by cathode
sputtering followed by solution of the backing.
The fissile layer acted as the common cathode of a double pulse ionization chamber for fission. The large
surface of the preparation required the construction of a chamber whose dimensions were considerably greater
than those usually used. The body of the chamber consisted of a section of a 380 mm diameter steel pipe with
screwed in steel flanges. The two halves of the double chamber were actually independent and identical pulse
chambers.
Both chambers were equipped with grids to shield the collector from positive ions. The chamber was worked
out from the theory put forward in paper [12]. The chamber was filled to atmospheric pressure with technical
argon, which was constantly purified by being passed through calcium shavings, heated to 300? C. A field strength
of 360 v/cm in the cathode? screen space and 1350 Vern in the screen? collector space provided for saturation
and a minimum capture of electrons by the screen.
The measuring equipment consisted of two amplifying channels, a coincidence circuit and a two-beam
pulsed oscillograph. A pulse, produced by a fragment, amplified and delayed by 1.5 ?sec, was conducted to the
vertical plates of one of the oscillograph beams. The undelayed pulse was formed into a standard one and acted'
upon the coincidence circuit, which triggered the seanning and intensity gate of the oscillograph. The photo
plate, after recording the fragments of nuclear fission in the form of two pulses, moved automatically 3-4 mm.
The measuring apparatus had the following characteristics. The amplification of both channels was main-
tained constant within 5% during the whole period of measurement and the linearity of the amplification within
1% during the operating time. The scanning capacity of the amplifying channels covered an energy of 1.2 Mev.
The time of electron collection and, consequently, the time of pulse growth was not greater than 2 ?sec. The
pulses lasted 20 ?sec, the scanning time of the coincidence circuit was 1.5 ?sec (the duration of the standard
pulses acting on it).
The spontaneous fission was observed without shielding from cosmic rays. At present one may consider it
established that the effect of spontaneous fission on natural uranium is approximately two orders greater than the
effect of fission by mesons and neutrons of cosmic radiation. U235 fission by slow neutrons was observed using a
20-25 cm paraffin shield around the chamber and a neutron source placed within this shield.
Experimental Results
In all, we recorded 780 cases of spontaneous U238 fission over a period of 1100 hours operation and about
4500 cases of U235 fission by slow neutrons. Combination of the kinetic energies of the fragment pairs for each
of these methods of fission gave a statistical distribution of the acts of fission according to the energies of the
two fragments.
Figure 1 shows such a distribution for spontaneous U238 fission.
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The scale of pulse amplitudes according to energy was graduated with a-particles of U238 and U. Papers
[13-15] show experimentally that more energy is expended in the formation of one ion pair by a fragment than
by an a-particle. However, it was assumed for the graduation that the energies expended in the formation of
one ion pair by the fragment and an a-particle are equal. This was done to facilitate the comparison of the ex-
perimental results with previous investigations.
t44
100
-V, 90
80
tic)
I::
o 60
.1) 50
E-4
4
30
The ratio of the fragment masses
?
274 2,47 223 2,03 184 1,68 ,54 1,41 1,29 1,185
109
b41144114701rer
4.04
4
7141t.441.6.
ArA6e
___
,P,".....;,,dt.;
44
i
zwit#0?40.7_,
air
.:
.
II
votrireArs,
"141107ere.
#4$14*
:\ ..
?
? ...
.-:. ?
-.:.t..-:
? ?. ? ...?
4
AP
.
?
..-::,....,...::::::....
? ...1
? ?
?
. :
.:..
? ?
. ?
?
, ? 1 .
s'? !-
. ?
, ..:...
. .?
? _.
_____
.30 40 50 60 70 80 90 100
The kinetic energy of fragment in climber I E1, Mev
Fig. 1. Statistical distribution of spontaneous U238 fission acts according to the
energies of the two fragments.
The individual fission acts are represented by points whose Descartes coordinates
correspond to the energies of the light and heavy fragments.
110
The statistical distribution of the fission acts according to the energies of the two fragments gave a series
of curves which characterize the two fission methods being compared.
To plot the energy spectra of the fragments (Fig. 2) we first calculated the number of pulses in each energy
interval of both coordinate axes and then combined the ,results for the two axes. The statistical distributions made
it possible to resolve the'energy spectra into peaks for light and heavy fragments. The peaks, especially those in
the case of light fragments, have considerable "tails" in the low energy range. The heavy fragment peaks correspond
quite markedly to a Gaussian curve. The characteristics of the energy spectra are given in the table on p. 726.
Figure 3 gives both spectra for a more graphic comparison. Besides certain differences in the form of the
spectra, a difference of approximately 2 Mev may be observed in their positions, which is not covered by the limits
of error.
The statistical distributions were further analyzed by using the auxiliary coordinate lines E1+ E2 = const and
EilEi = const (see Fig. 1). According to the law of the conservation of momentum, the ratio of the energies of the
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724
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200
0
WOO
750
A
30 40 50 60 70 80
Kinetic energy of fragments E1, Mev
90 100
110
" 5
00500
15)250
30
40 50 50 70 80 90 100 110
Kinetic energy of fragments El, Mev
Fig. 2. Energy spectra of fragments from spontaneous U238 fission and
fragments from U833 fission by slow neutrons. A) Data for light frag-
ments; 0) data for heavy fragments; 0) data for all fragments.
200
150
2
100
bO
cts
L.. 0
k-3
13
0
woo 2
750
?
500
bO
cci
250
"0
0 Z
110
30 40 50 60 70 80 90
The kinetic energy of fragments E, Mev
Fig. 3. Comparison of the energy spectra of fragments. ii) Spontaneous 038
fission; 0) U235 fission by slow neutrons.
100
by slow neutrons
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120
00
/no
00
80
0
0.
4-?
0
40
60
20
04414
30 100 110 120 130 140 150 160 170 180
Total kinetic energy Eheavy + Elight Mev
Fig. 4. Distribution of fission acts according to the
total kinetic energy of the two fragments.
0) Spontaneous U238 fission; 0) U235 fission by
slow neutrons.
600
400
300
200 I
?
0
100 -0
12
.150
110
100
90
80
1,2 1,4 1,6 1,8 2,0 2,2 2,4 2,6
neavy 4light
Fig. 6. The relation of the average total kinetic
energy of the two fragments to the ratio of the
fragments' mass. 0) Spontaneous U233 fission;
0) U235 fission by slow neutrons.
118
128
138
148
158
168
178
108
98
88
78
68
el
178 '?heavy
58/1
light
Fig. 5. Distribution of fragments according to
mass. 0) Spontaneous U238 fission; 0) U235
fission by slow neutrons. The mass numbers of
light and heavy fragments are plotted along the
abscissa, assuming that the mass number of the
fissile nucleus equals 236.
100
90
80
1.B.p 70
60
50
40
30
130 140 150 160 170
Eheavy Elight' Mev
Fig. 7. The relation of the average kinetic energy
of light and heavy fragments to the total kinetic
energy of the fragments. 0) Spontaneous U238
fission; 0) U226 fission by slow neutrons.
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fragments E2jE1 equals the reciprocal ratio of their masses AVA2. For the group of fission cases lying above
and to the left of the line EilEi. =1, the symbol El corresponds to the energy of the heavy fragment and may be
substituted by Eheavy. Similarly, E2, Ai, and A2 may be substituted by Elight, Aheavy, and Alight. Figure 4
gives the distribution of acts of fission according to the sum of the kinetic energies of the two fragments in the
two cases being compared. The most probable and the average total energies for spontaneous fission were approxi-
mately 4 Mev less than those for fission by slow neutrons with a peak half-width 20% less.
TABLE
Characteristics of the Energy Spectra of Fission Fragments
Characteristic
Spontaneous fission
Fission by slow n eutrons
light fragments
heavy fragments
light fragments
heavy
fragments
The most probable energy,
Mev
90.0 ? 0.3
54.4
0.4
92.3 I 0.12
56.6 ?0.15
The half-width of the peak,
Mev
17.5
21.1
19.2
23.5
The ratio of the most probable
energies
16
1 63
The ratio of the height of the
peak for light fragments
to the height of the peak
for heavy fragments
1
13
1
15
The ratio of the height of the
depression between the
peaks to the height of the
peak for light fragments
0
33
0
42
By summing the acts of fission in the intervals between the coordinate lines EilEi = Ai/A2 = const, we ob-
tain the distribution of fragments according to mass (Fig. 5). Within the limits of error, the points of both methods
of fission lie on one curve.
The relation of the average total kinetic energy of the two fission fragments to the ratio of the masses of
the fragments (Fig. 6) is similar for spontaneous fission and for neutron-produced fission. The average energy of
the fragments from spontaneous fission is continually less than the average energy of the fragments from fission
by slow neutrons.
Figure 7 gives the curves for the average energy of a group of light and heavy fragments against the total
kinetic energy. The average energies of spontaneous fission and of neutron-produced fission increase with an
increase in the total energy, but the energy of the light fragment increases more slowly.
Discussion of Results
The statistical distribution according to the energies of the two fragments from spontaneous fission and
from fission by slow neutrons has the following characteristics. The probability maxima correspond to unsym-
metrical fission; the energies Of the light and heavy fragments fluctuate over a considerable range; the energy
of one of the nuclear fragments fluctuates over almost as wide a range when the energy of the other fragment is
fixed.
Figure 1 includes a number of points that lie in the field of the bisector of the coordinate angle and they
could be considered as cases of almost symmetrical fission. There are also points which could denote cases of
fission with an extremely low energy of one or both fragments. However, both groups of points should be con-
sidered rather as resulting from the energy distribution of the fragments being distorted by energy losses in the
actual preparation layer.
The peaks of the light and heavy fragments in the energy spectra of fragments from fission by slow neutrons
(Fig. 2) have somewhat greater breadths than those obtained in works [4-91. The effects of the main sources of
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additional broadening were evaluated. Of all the factors which could have caused the broadening of the peaks
in our work, the most probable were a variation in the amplification coefficient and the absorption of fragments
in the preparation layer. Other causes for broadening (the scanning capacity of the ionization chamber, the
scanning capacity of the amplifying channels, errors in measuring the amplitude of the pulses and statistical errors)
were approximately the same in works [4-6] as in our experiment. They were less in works [7-9] as apparatus
with a greater scanning capacity was used.
The introduction of corrections for the variations in the amplification coefficient would decrease in half-
width of the peaks for light and heavy fragments from 19.2 to 15 Mev and 23.5 to 22.6 Mev, respectively. To
evaluate the broadening of the peaks due to absorption of fragments in the preparation layer for the peaks of
light and heavy fragments taken from paper [4], new distributions according to energy were plotted, taking into
account absorption in a preparation layer with an area density of 0.15 mg/cm2 of U308. It was found that the
additional half-widths acquired by peaks were 3.5 Mev for the group of light fragments and 5.5 Mev for the
group of heavy fragments. Taking these values into account, the half-widths of the peaks were found to be
14.5 and 22 Mev. In the calculations, the peaks were assumed to have a Gaussian shape and the partial half-
widths were summed according to the law of the addition of random errors. Due to the extremely approximate
character of the calculations, the corrected values for the half-widths may be considered as agreeing quite well
with the results of other work in which the half-widths of the peaks of light and heavy fragments range from 17
and 22 Mev in earlier work [4],to 12 and 19 Mev in contemporary work [7-9].
It was found that the average total kinetic energy of fragments from spontaneous U238 fission was about
4 Mev less than that of U235 fission by slow neutrons. This was also confirmed by the results given in paper [1],
in which the energy spectrum of fragments from spontaneous U238 fission was displaced by about 1.5 Mev toward
lower energies in relation to the spectra of U235 fragments, although the statistical accuracy was not sufficient for
absolute confirmation. It is difficult to draw any conclusions from this difference in energies as different fissile
nuclei were compared: U238 in its ground state and U236 in an excited state. A comparison of the energy character-
istics of spontaneous U238 fission and those of the photofission of this nucleus at an excitation energy close to that
of the fission threshold would have been much more interesting. At the present time the literature does not con-
tain data for such a comparison.
On the mass yield curve (Fig. 5), the graduation of the abscissa in mass numbers of fragments cannot
correspond simultaneously to the fission of U238 and U238 nuclei. The scales for the mass numbers of U236 and
U238 should have been somewhat different. However, the inaccuracy in the graduation of the scale was con-
siderably less than that in the resolving capacity of such a method for determining the mass yield curve. The
difference in the distributions according to mass, which could have been caused by the difference in the mass
of the fissile nuclei, were covered here by the spread of the curve in both directions as a result of energy losses
in the preparation layer. Therefore, the curve shows the presence of fragments with mass numbers greater than
168 and less than 68. The yield of such fragments is zero, as is known from radiochemical investigations. A
considerable yield was also observed in the range of symmetrical fission and the possible difference in the yields
of fragments from fission by slow neutrons and from spontaneous fission, as detected in paper [16] for Cm242, was
completely screened.
The graph of the relation of the average total kinetic energy to the ratio of the fragment masses (see Fig. 6)
showed that fission becomes more symmetrical both in the case of spontaneous fission and in the case of fission
produced by slow neutrons when the total energy increases. When Aheavy/Alight tends toward unity, the curves
show a fall. This should be considered as due to the fact that in the region of the line EilEi =1 the statistical
distributions according to the energies of the two fragments (see Fig. 1) include mainly fission acts which have
a substantial deficiency in total energy due to the considerable loss of energy by the fragments in the preparation
layer.
An increase in the symmetry of fission with an increase in the total energy of the fragments may also be?
seen in Fig. '7, in which the curves of the average energy of light and heavy fragments approach each other when
the energy increases. This results in a lower dispersion of energy by the light fragments and in a different width
for the peaks of light and heavy fragments in energy spectra in the case of neutron fission and spontaneous fission.
In this work it was found that the statistical distributions of fission acts according to the energies of the two
fragments and the consequences of this distribution were quite similar for spontaneous U238 fission and U235 fission
produced by slow neutrons. Of the insignificant differences that exist, the greatest is that the average total kinetic
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energy of the two nuclear fragments and the average energy of the light and heavy groups of fragments is about
4 Mev and 2 Mev, respectively, less for spontaneous U238 fission than for U235 fission by slow neutrons'. The re-
sults of this work indicate the similarity of the mechanisms of these two methods of fission.
728
LITERATURE CITED
[11 W. J. Whittenhouse and W. Galbraith, Philos. Mag. 41, 429 (1950).
[2] G. C. Hanna, B. G. Harvey, N. Moss, and P. R. Tunnicliffe, Phys. Rev. 81, 466 (1951).
[3] E. Segre and G. Wiegand, Phys. Rev. 94, 157 (1954).
[4] W. Jentschke and F. Prancl, Z. Physik 119, 696 (1942).
[5] W. Jentschke, Z. Physik 120, 165 (1943).
[6] A. Flammersfeld, P. Jensen, and W. Gentner, Z. Physik 120, 450 (1943).
[7] D. C. Brunton and G. C. Hanna, Canad. J. Res. 28A, 190 (1950).
[8] D. C.. Brunton and W. B. Thompson, Canad. J. Res. 28A, 498 (1950).
[9] J. S. Wahl. Phys. Rev. 95, 126 (1954).
[10] A. B. Smith, P. R. Fields, and A. M. Friedman, Phys. Rev. 106, 779 (1957).
[11] E. Segre, Phys. Rev. 86, 21 (1952).
[12] 0. Buneman, T. E. Granshou, and J. A. Harvey, Canad. J. Res. 27A, 191 (1949).
[13] R. B. Leachman, Phys. Rev. 83, 17 (1951).
[14] R. B. Lechman, Phys. Rev. 87, 444 (1952).
[15]
H. W. Schmitt and R. B. Leachman, Phys. Rev.
102,
183
(1956).
[16]
E. P. Steinberg and L. E. Glendenin, Phys. Rev.
95,
431
(1954).
Received July 1, 1957
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RECRYSTALLIZATION OF URANIUM BY THE ACTION OF
CYCLIC HEAT-TREATMENT
A: A. Bochvar, G. I, Tomson, and N. T. Chebotarev
During cyclic heat-treatment in the temperature range 100-550? C with cycles of
50 second duration, recrystallization resulting in a refinement of the original microstructure
occurs in uranium quenched from the y -phase region, as well as in uranium annealed in the.
y - phase and in cast uranium, not subjected to additional deformation. Recrystallization
commences at places with maximum distortion of the crystal lattice.
In 1956-1957, papers [1-3] appeared, in which it was stated that polygonization occurs in uranium by the
action of cyclic heat-treatment, resulting in the formation of subgrains or the breaking down of the original
grains to smaller grains, differing in orientation by a few degrees only.
The present paper describes an investigation of the variation in microstructure of uranium, quenched from
the y -phase, uranium annealed in the y -phase region and cast uranium in the process of cyclic heat-treatment
in the temperature range 100-550* C with cycles of 50 second duration. Our observations show that recrystalliza-
tion occurs during cyclic heat-treatment, a fact previously mentioned only in paper [4].
Brief Description of the Method
Cyclic heat-treatment of cylindrical uranium specimens, 5 mm in length and 5 mm in diameter, was
carried out in an automatic apparatus, with induction heating and with the use of helium as a protective medium
against oxidation [5].
Parameters of the cycle:
Upper temperature 540-550? C
Lower temperature 100? C
Mean rate of heating 22 deg/sec
Mean rate of cooling 25 deg/sec
Holding time at upper temperature 12-13 sec
Since the variation in microstructure of uranium with different impurity contents during cyclic heat-treat-
ment had qualitatively the same character, the results of chemical analysis are not given.
The microstructure was revealed by electrolytic polishing in a solution of the following composition:
Glacial acetic acid 1 part
Saturated aqueous solution of
? chromic anhydride (specific
gravity 1.50) 1 part
Water 2 parts
The x-ray photographs of the polished sections were made in RKU-86 cameras using cobalt radiation.
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a
Fig. 1. Variation in microstructure of quenched uranium by the action of cyclic heat-
treatment, a) Specimen before cyclic heat-treatment (x 70); b, c) specimen after 450
cycles (x 70); d) specimen after 450 cycles (x 200); e) specimen after 2000 cycles
(x 200).
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EXPERIMENTAL DATA
Metallographic examination of the specimens before and after cyclic heat-treatment showed that in
uranium quenched from the y -phase region recrystallization occurs by the action of the thermal cycles, re-
sulting in a considerable refinement of the original structure. Figures 1, a-e show the variation in microstructure
of quenched uranium with the number of cycles.
For comparison of the data characterizing the effect of cyclic heat-treatment on the microstructure of
quenched uranium with the results of corresponding isothermal annealing, a number of quenched specimens were
annealed at a temperature of 550? C for 5 hours 30 minutes. This annealing time corresponded to the time at
which the specimens remained at a temperature of 540-550? C in the course of 1500 cycles. As will be seen
from Fig. 2, showing the same place before and after isothermal annealing* no appreciable change took place
In the microstructure.
a
Fig. 2. Microstructure of quenched uranium before and after isothermal annealing at 550? C
for 5 hours 30 minutes (x 200). a) Specimen before isothermal annealing; b) specimen
after isothermal annealing.
a
Fig. 3. X-ray photographs of quenched uranium. a) Initial con-
dition; b) condition after isothermal annealing at 550? C for 6
hr 30 min, c) condition after 1800 cycles in the range 100-550 ? C.
* After isothermal annealing, the specimen underwent additional electropolishing and etching.
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Recrystallization of quenched uranium by the action of cyclic heat-treatment is also clearly revealed by
the method of x-ray structural analysis. Figure 3 shows x-ray photographs of three specimens of uranium containing
approximately 0.1% carbon after a) quenching, b) additional isothermal annealing at 550? C for 6 hr 30 min
and c) 1800 cycles.
Comparison of the x-ray photographs shows that the grain size remains practically unaltered after isothermal
treatment, whereas there is considerable grain refinement after cyclic heat-treatment.
a
Fig. 4. Variation in microstructure of uranium annealed in the y -phase by the action of
cyclic heat-treatment. a) Specimen before cyclic heat-treatment (x 70); b) specimen
after 2000 cycles (x 200).
Uranium annealed in the y -phase region (annealing temperature 850? C, rate of cooling 1.5 deg/min),
likewise recrystallizes by the action of cyclic heat-treatment. Figure 4 shows the microstructure of this uranium
before and after cyclic heat-treatment.
The photomicrographs shown in Fig. 5 illustrate the structural changes in cast uranium by the action of
cyclic heat-treatment, and show evidence of considerable recrystallization of the uranium.
732
a
Fig. 5. Variation in microstructure of cast uranium by the action of cyclic heat-treatment.
a) Specimen before cyclic heat-treatment (x 70); b) specimen after 1800 cycles (x 200).
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Thus, in the conditions specified above, cyclic heat-treatment provides conditions which facilitate the
process of recrystallization of uranium quenched or annealed in the y - phase region and also of cast uranium of
different degrees of purity.*
Recrystallization of uranium by the action of thermal cycles commences along the shear twins and lines
and also along the grain boundaries (Fig. 1, c, d) that is to say, at the places where the crystal lattice is strongly
distorted. This is in agreement with the widely accepted viewpoint of the places of origin of recrystallization
centers.
Quenching stresses do not determine the character of the variation in microstructure by the action of
cyclic heat-treatment, since the observed character of the variation in microstructure is the same in quenched
uranium as in annealed uranium.
The original grain size evidently has some effect ()lithe rate of the recrystallization process by the action
of cyclic heat-treatment. Thus, in Fig. 1,c, a large grain in which the recrystallization process has just
commenced stands out on a background of fine-grain recrystallized structure. Some reduction in the recrystalli-
zation rate was also observed in coarse grain uranium annealed in the y -phase.
LITERATURE CITED
[1] H. H. Chiswik and L. Kelman, Nuclear Power Metallurgy and the Action of Irradiation on Materials
(Papers read by Foreign Scientists at the International Conference on the Peaceful Uses of Atomic Energy)
(Metallurgy Press, 1956), p. 612.
[2] F. Foot, Ibid., p. 89.
[3] H. H. Chiswik, Trans. Amer. Soc. Metals 49, 622 (1957).
[4] B. W. Mott and H. R. Haines, J. Inst. Metals 80, 621 (1952).
[5] A. A. Bochvar and G. I. Tomson? J. Atomic Energy (USSR) 2, 6, 520 (1957).??
[6] J. Bloch, Acta Metallurgica 6, (2), 126 (1958).
Received March 18, 1958
? In the article [6], it is pointed out that recrystallization of uranium also occurs by the action of irradiation.
?* Original Russian pagination. See C. B. Translation.
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TISSUE DOSES OF FAST AND ULTRA-FAST NEUTRONS
M. I. Shal'nov
An investigation has been carried out of depth doses in irradiation of tissue-like
dummies (water, paraffin) with broad beams of fast and ultra-fast neutrons generated in ,
the 1.5 meter cyclotron by bombarding a thick beryllium target with deuterons accele-
rated to 13 Mcv (the reaction Be9(d, n)B10) in the six-meter synchrocyclotron by bom-
barding a thick copper target with deuterons accelerated to 280 Mev (deuteron stripping
reaction), and in the six-meter synchrocyclotron by boinbarding,a beryllium target with
protons having an enervy of 480 Mev (proton charge-exchange reaction).
The results of the investigation, when applied to the case of irradiation of tissue
with narrow and broad beams of monoenergetic neutrons, permit conclusions to be formed
concerning depth doses with any spectrum of neutrons, and make possible the calculation
of the mean tissue dose that can be used in comparative radiobiology. Moreover, data
on attenuation of the dose of neutrons of various energies in hydrogen-containing media
may be of help to the engineer in the construction of shielding.
Experimental and theoretical curves of the variation of the maximal tissue dose
with hardness were obtained for broad and narrow neutron beams in the energy interval
0.1-500 Mev. These curves can be used for calibrating dosimeters.
Views are expressed concerning methods of approach to evaluation of the biological
effectiveness of nuclear radiations, and to establishing the maximum permissible dose for
man.
Tentative values are given for the maximum permissible neutron fluxes for man.
EXPERIMENTAL TECHNIQUES
For a precise determination of tissue doses of fast and ultra-fast neutrons, the depth distribution of absorbed
energy was investigated in tissue-like media irradiated at the 1.5 meter cyclotron and the six-meter synchro-
cyclotron.
In the cyclotron, neutrons were generated by bombardment of a thick beryllium target with deuterons
accelerated to 13 Mev (Be9(d, n)131? reaction). The spectrum of neutrons thus formed has the following character-
istics: a considerable fraction of the, neutrons have energies from 2.5 to 5 Mev; in the region from 5 to 13 Mev,
the number of neutrons per unit interval of energy falls off in proportion to e- 1).434 E [1]. The mean energy of
the neutrons is 5.6 Mev.
The average intensity of the neutron beam at a distance of 100 cm from the target was 2'10-7 neut/cm2 per
sec. The reaction Be9(d, n)131? is accompanied by y-radiation having several lines of different intensities in
the region of the spectrum from 0.72 to 7 Mev, corresponding to the energy levels of the excited B" nuclei. y-
photons are emitted with energies of 0.72 Mev (approximately 0.7 per neutron) and 5 Mev (approximately 0.97
per neutron) [3].
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Irradiation with the cyclotron was carried out in the following manner. The dummy, made in the form of
a rectangular parallelepiped 30 x 30 x 42 cm out of paraffin blocks 30 x 30 cm with a thickness of 2 and 5 cm,
was placed in the path of the external beam? between the cyclotron chamber and the fixed yoke of the magnet
toward which the beam was directed. The neutrons fell on a surface 30 x 30 cm , at right angles to it. Back-
scattering of neutrons from the iron yoke of the magnet was important only at large depths within the dummy and
was taken into account in analyzing the results of the measurements.
The measurements were conducted with the help of small ionization chambers with condensers, placed in
compartments in six blocks, five to a block, each block being at a different depth along the path of the beam.
Thus, 30 chambers were exposed at once, permitting readings to be taken in 30 points at six different depths, for
one exposure. This insured great accuracy in the measurement of the relative depth doses in each exposure. The
materials of the walls of the chambers (bakelite) and the condenser (styroflex) were close to paraffin in hydrogen
content, so that the presence of the chambers could not appreciably affect the distribution of neutrons in the dummy.
The contribution of the y-background to ionization was taken into account by the method of differential measure-
ments. For this purpose, aluminum chambers were used alongside the bakelite chambers; these had the same sen-
sitivity to electromagnetic radiation (200 key and 1.3 Mev) as the bakelite chambers. In the differential method
of measurement, the dose resulting from external y-radiation was excluded, as well as that due to y -radiation
resulting from neutron capture in the paraffin; only the biologically most effective component of the recoil pro-
tons and heavy nuclei was considered. The calibration of the bakelite chambers for neutrons was carried out with
the help of a Po + Be-source. It has been shown experimentally and theoretically that ionization of 1 cgs unit/cm3
in an air cavity corresponds to 85 erg/g energy absorbed in hydrogenous material. Thus, the ionization in the
bakelite chambers (after allowing for the ionization from y-background), produced mainly by recoil protons
ejected from the walls, could serve as a measure of the absorbed energy of the neutrons at any depth of th'e irra-
diated dummy. The ionization current in the chambers was determined from the reduction in the charge on a
fixed condenser, using a "Sosno" commercial unit to measure charge.
In experiments on the synchrocyclotron, two neutron spectra were used: the spectrum of the stripping reaction
(d, n) in a thick copper target (Ed = 280 Mev) and the charge-exchange spectrum of the reaction (p, n) in a beryllium
target (Ep =480 Mev).
The neutron spectrum of the former reaction is well described by the theory of Serber, and is characterized
by maximum neutron emission at the energy E = Ed/2.
The mean energy of stripping neutrons was 140 Mev, and of charge-exchange neutrons was approximately
380 Mev.
The neutron flux in the first case was approximately 2- 107 neutrons/cM 2- sec at 250 u a and a distance of
2 m from the target (along the axis of the beam); in the second case, the flux was about 8.106 neutrons/cm2- sec
at the same distance.
Exposure of the dummies was carried out as follows. Cylindrical containers filled with water were situated
at a distance of 6-10 m from the target along the axis of the emerging electron beam. With the help of thimble
chambers, immersed in water, and made of hydrogen-containing material, ionization measurements were con-
ducted at different depths along the path of the beam. Containers having diameters of 10, 20, and 30 cm and a
height of 30 cm were used in different experiments. Similar measurements were carried out in the paraffin
dummy described earlier. Holes were drilled in one of the blocks for an ionization chamber. This block, together
with the chamber, was placed at various depths along the path of the beam. Thimble chambers and a condenser
were also used. The ionization current was measured with the aid of RIP and "Pion" commercial x-ray meters.
To monitor the variations of intensity during irradiation, a supplementary instrument with an ionization chamber
(monitor) was used, the readings from which supplied corrections that were introduced into the fundamental measure-
ments.
Calibration of the chambers showed that an ionization of 1 cgs unit/cm3 in air corresponds to the same
quantity of absorbed energy as in irradiation with fast neutrons: 85 erg/g.
Depth measurements using wide neutron beams permitted us to estimate the contribution of multiple neutron
scattering to the tissue dose (accumulation factor), and to form a definite idea of the distribution of depth tissue
doses under these conditions. Tissue doses were expressed in erg/g, referred to a standard flux of 106 neutrons/cm2.
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EXPERIMENTAL RESULTS
In Fig. 1, experimental curve 1 represents the depth tissue doses according to the results of measurements
in paraffin irradiated from the cyclotron with neutrons having a mean energy of 5.6 Mev. This curve shows the
reduction in the tissue dose with depth[ see Equation (1)] as a result of neutron absorption by the dummy material
and divergence of the beam according to the inverse square law
J47* (x) ? (0) -x/L
? ( ti e
(1)
where x is the depth in cm; R is the distance from the target (in this case, 100 cm); L is the relaxation distance
in cm (L = 11.6 cm); W (0) is the neutron energy in erg/g, absorbed at the surface with a narrow beam; B is the
accumulation factor, taking into account the contribution of multiple neutron scattering.
E=5,6 Mev (cyclotron)
?
5 IC 15 20 25 30 cm
Fig. 1. Experimental and theoretical curves of depth tissue doses for a wide
neutron spectrum (E = 5.6 Mev).
1) Experimental curve; 2) theoretical curve, on the assumption that R>> x =
= 30 cm; 3) curve obtained by normalization, according to the spectrum of
Tait's theoretical curves; 4) theoretical curve for a narrow beam of wide-
spectrum neutrons.
The value of B that satisfies the experimental data is 2.14 (1- 0.3 e- x/3). At the surface of the object
(where x = 0) B =1.5; at depths beyond 15 cm, B = 2.14. At large target-to-object distances (R? x), where the
divergence of the beam can clearly be neglected, curve 1 (Fig. 1) can be replaced by curve 2, for which the
quantity ,_W(0)2 expresses the dose at the surface with a wide parallel beam of neutrons. Tait [4] has Investi-
gated the theory of depth tissue doses for wide parallel beams of monoenergetic neutrons in the energy interval
from 0.5 to 5 Mev.
The depth doses for wide monoenergetic beams, calculated in Tait's work [4], may be approximated by
an expression similar to Formula (1), with B = 1.58 (1-0.365 e- x/s). By adjusting Tait's theoretical curves for
the cyclotron spectrum, we obtained curve 3, which differs slightly from our experimental curve 2. This served
as a basis for the choice of an expression satisfying the values of depth tissue doses for wide beams of mono-
energetic neutrons:
Wl" (x) = W (0) 2,37 (1 ? 0,365. e-xI3) ex/L,
(2)
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where W (0) is the dose at the surface for a narrow beam of monoenergetic neutrons (without regard for multiple
collisions), which is determined as the product of the incident neutron flux 11 times the mean energy of the
ionization particles formed as a result of nuclear processes, En i o rfi, where ni is the number of atoms of
some element per cm3 of tissue, a/ is its neutron reaction cross section, and "Ei is the mean energy of the
ionizing particle: W (0) = n E ni a iTi . When 11 = 1 neutron/ cm2, W(0) = Eni ojE Mev/cm3 (or erg/cm3).
For neutrons of various energies, W(0) has the values cited below:
Neutron energy,
Mev
0,5
1
2 -
5
10
15
W(0) Mev/g at
1 neutron/cm2
0.1
0.15
0.20
0,30
0,38
0,40
14
100
10
The relaxation length L, for a wide neutron
beam in the energy interval 0.5-15 Mev, is given
with sufficient accuracy by the relationship L = 1/0.7,
where is the relaxation length for a narrow neutron
beam, which in tissue-like media is taken as equal
to 2,8.E?'5 (E in Mev, /in cm).
N.
100
10
5
ft)
15
a)
20
25
30cm
2 4 6 8 10 12
15 18 20 22 N 26 28 30 cm
Fig. 2. Depth tissue doses for narrow (a) and wide (b) beams of mono-
energetic neutrons with energies from 0.5 to 15 Mev.
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The relative depth tissue doses for narrow beams of monoenergetic neutrons, characterized by exponentials,
and for wide neutron beams, calculated from Equation (2), make possible the determination of depth tissue doses
of neutrons for any spectrum in the interval 0.5-15 Mev (Fig. 2).
For objects having sufficient thickness (e. g., 30 cm, as in our case), the assumption that the accumulation
factor B equals 1.5 at the surface may be considered reasonable. The values obtained theoretically [4] and ex-
perimentally [5, 6] are close to this value. If we set the narrow-beam surface doses equal to unity, then according
to Tait the coefficients of increase for the surface dose for corresponding wide beams of monoenergetic neutrons
will be:
Energy, Mev
Coefficient of increase of
dose at surface
0.5
1.25
1.0
1.20
2.0
1.15
3.0
1.20
4.0
1.32
5.0
1.25
_ Experimental curves of the deep distribution of absorbed energy of ultra-fast neutrons having average
energies of 140 and 380 Mev are set forth in Fig. 3,a and b.
E=/40 .Mev (synchrocyclotron)
1,0
0!
'
10
15
(I )
20'
E380 Mev (synchrocyclotron)
25
30 cm
-2-
3
5
10
15
20
25
30 cm
Fig. 3. Experimental (1) and theoretical (2? 3) curves of depth tissue doses of
ultra-fast neutrons: a) for deuteron splitting spectrum (E = 140 Mev), b) for
proton charge-exchange spectrum (E = 380 Mev).
The results of measurements in water dummies where1=140 Mev showed that the difference between doses
at the surface and at depths up to 10 cm, in dummies of 10, 20, and 30 cm in diameter at the same points (0.25,
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0.5, 1.0, 1.5 cm etc.), were not very large, and fell within the experimental error. Therefore, in Fig. 3, a the
points of curve 1 up to a depth of 10 cm are for averaged experimental values for these dummies. In measure-
ments with the paraffin dummy, its over-all thickness remained constant and equal to 42 cm.
We may consider the depths of water and paraffin employed to have been sufficiently great that multiple
scattering even of ultra-fast neutrons would be effective at surface and depth doses.
In consequence of the fact that exposure was carried out at a great distance from the target (6-10 m), the
incident neutron beam can be regarded as parallel. Curves 2 and 3 in Fig. 3,b, lying below curve 1, were ob-
tained on the basis of a calculation of the absorbed energy of recoil protons and protons and deuterons from
spallation? which was determined by means of numerical integration (with respect to depth) of Expression (3),
taking into consideration: a) relaxation length of neutrons for single collisions with nuclei of tissue atoms, b)
spectra of secondary particles, and c) energy losses of particles in the tissue:
Eimax
Wi (x) = W e-xlidx a (Es) dE
0
(3)
where x is the depth in cm from the surface of the dummy; g is a depth equal to x? r (r is the range of the
particle); / is the relaxation length for single collisions, in cm-1; a(E) is a function characteristic of the
spectrum ot the particles; Eig is the energy of particles with the range r = x? ; Ei max is the maximum
energy of particles in the spectrum; and Wi is a normalizing factor.
Information about the spectra a(E1) of particles from recoil and spallation were obtained by us from data
in the literature [7-10]. The energy absorbed at various depths, of recoil C, N, and 0 nuclei, was calculated as
the exponential Wie-xii , determined only by the relaxation length / of narrow-beam neutrons.
From the results of calculations for narrow beams of neutrons with energies of 40, 90, 220, and 380 Mev,
depth dose curves were plotted (Fig. 4), which made it possible, by means of linear interpolation and extrapola-
tion, to extend our conception of depth doses to neutrons of any energy in the interval from 40-500 Mev. First
values of the absorbed energy at the maximum were found (Fig. 5, curve 1), after which a family of curves was
obtained characterizing the distribution of depth doses as a percent of the maximal dose (Fig. 6). Normalization
of the whole family of curves according to the spectra obtained in the experiments and according to the absolute
values at the absorption maximum served as a foundation for constructing curves 2 and 3 of Fig. 3. As a criterion
of the reliability of the depth doses expressed by these curves, we may take the total and differential profiles of
n? p scattering taken for energies of 40, 90, 220, and 380 Mev; n? p scattering has now been studied with great
accuracy and makes the largest contribution to the dose (Fig. 4). The fact that the experimental values exceed
the theoretical reflects the contribution of multiple scattering of neutrons to the absorbed energy (accumulation
factor, equal to 1.5 in this case also).
The agreement of the mean value of the accumulation factor for the dose of ultra-fast incident neutrons
in the wide beam with the corresponding value of the factor for fast neutrons with dummies of 30-40 cm thickness
is entirely natural. For broad beams of monoenergetic neutrons it was assumed that up to energies of 140 Mev
they give a distribution of depth doses somewhat different from the distribution for narrow beams (Fig. 6), but at
energies > 140 Mev they give the same distribution as for narrow beams.
On the basis of the constancy of the accumulation factor over the whole energy interval under consideration,
for fast and ultra-fast neutrons, a curve of values of maximum doses was plotted for broad neutron beams (curve
2, Fig. 5).
The curve of maximum values of the tissue dose for broad neutron beams can be used in practice for cali-
brating dosimeters. All instruments for measuring the dose in air in roentgens equivalent physical (REP) must
meet the requirement (in the absence of an irradiated object, where neutrons interact only with the material of
the instrument) that the instrument have the same variation with hardness in the working interval of neutron
energies as the tissue. A second requirement is that the depth doses in the tissue be distributed in the same
manner at these energies as under conditions of irradiation with x- or y -rays. In neutron dosimetry these re-
quirements are substantially met up to 15-20 Mev, i.e., up to those energies at which the maximum tissue dose
is produced at the surface of the object. At higher energies, measurement of the neutron dose is best done in
absolute units (erg/cm3).
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In calibrating dosimeters from the maximal tissue doses (curve 2, Fig. 5) one Must not forget that such a
calibration does not meet the requirements of experimental radiobiology. In calibrating dosimeters for measuring
irradiation doses to animals, suitable corrections must be introduced.
90 Mev
0 5 10 15 20 25 30 2 0 5 m f. jn jg an g/cm2
r
C 1T1
Fig. 4. Depth tissue doses, calculated in absolute units (Mev/g) for narrow beams of mOnoenergetic
neutrons with energies of 40, 90 220, and 380 Mev for unit incident fluxes. 1) Recoil protons; 2)
spallation protons (total for C, N, and 0 nuclei); 3) spallation deuterons (total for the same nuclei)
4) recoil C, N, and 0 nuclei; 5) cumulative curve of absorbed energy.
To compare the biological action of neutrons with the action of any other form of radiation (e.g., x- or
y -rays) a comparable dosimeter quantity in total-body irradiation is the mean tissue dose, expressed in the
same units, best of all in absolute units of absorbed energy (erg/g). The mean tissue dose is defined as the ratio
of the total energy absorbed by the object to its mass. Under conditions of different hardness, the mean tissue
dose is measured by highly cumbersome methods; study of the depth distribution of absorbed energy in a tissue-
like dummy is a necessary step in these measurements.
Let the mean tissue doses of all layers of the object being irradiated be distributed as the values of the
function c4.7(x). These values may lie close to the distribution curve of depth doses along the axis of the beam,
or below the curve (but not above it). In this and other cases, the mean tissue dose can be expressed by the
equation
a
W= c (x) dx,
a .o
(4)
where a is the actual or effective thickness of the biological object.
If the values of W (x) are close to the depth doses along the axis of the beam, then -IN (x) is replaced by
W" (x) from Equation (2) or from graphs reflecting the same dependence.
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' The investigation of deep doses of ultra-hard y-radiation in paraffin at maximal y-quanta energies of 80,
150, and 250 Mev, generated in the synchrotron, show that the distribution of these doses is almost the same as
that from neutrons with energies of 100, 140, and 170 Mev, respectively. In these cases, it is possible to compare
10
.2
,
.? 1
r
Accumulation factor
r
?
01
1
Neutron energy
100
Fig. 5. Dependence of maximum tissue dose
object of 30 cm thickness).
1) For a narrow neutron beam; 2) for a broad neutron beam; 3) for a
broad neutron beam, according to Snyder [11].
on neutron
1000
energy (for an
the biological effect of hard bremsstrahlung with that of ultra-fast neutrons on the basis either of maximal or
of mean tissue dose. But in the majority of cases, where no such similarity is observed, the mean tissue dose is
the sole criterion for comparing the biological effectiveness of radiations.
The Biological Effectiveness of Neutrons and the Maximum Permissible Dose
The folpwing radiobiological data are the main source of our information for establishing the coefficient
of relative biological effectiveness (OBE) of one type of radiation in comparison with another:
a) curves of survival of animals as a function of radiation dose of a particular type, where the OBE is
defined as the ratio of the LD-50/30 for radiations of two different types;
b) curves of the mean survival time as a function of the dose of a particular type of radiation;
c) reduction of the latent period before the appearance of some biological effect, in chronic irradiation
with small doses. In this case the time of appearance of certain remote consequences of irradiation? e.g.,
cataract or cancer? during the life of the animal can be considered.
The most reliable of these statistically are data concerning the comparative magnitudes of the LD-50/30.
In our experiments on acute irradiation of animals, from a comparison of the LD-50/30 for neutron and
x-ray radiation, coefficients of relative biological effectiveness are obtained, equal to 3-4 in the case of
neutrons having a mean energy of 5.6 Mev, and about 2 for neutrons of 140 Mev mean energy (Fig. 7). If
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coefficients of relative biological effectiveness could be used in establishing. the maximum permissible doses for
.chronic neutron irradiation. in man, then an estimate of the inaxinium permissible intensity of neutron beams
could be made directly on the basis of curve. 2, Fig. 5. But the experimental coefficients cited above characterize
the relative biological effectiveness of neutrons only for cases of single, acute exposure, whereas the maximum
permissible dose for man must be defined with regard for the sharp increase in the biological effectiveness of
neutrons in the case of chronic exposure. to small doses. As the experiments indicate, the consequences of the
5,10
70 411 1 90
40
100
220
- 220
is
--- -
------"---
--
'
-...-......-4.4.Y..
i -
---
40
49
10
2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 cm
2
6 8 10
12 14 16 18 10 22 24 26 28 30
b)
Fig. 6. Depth tissue doses of neutrons (percent of maximum dose):
a) for narrow beams; b) for wide beams. (Figures on curves represent
neutron energy in Mev.
chronic action of small doses (10-30 REP/day) are more striking than the effects of acute exposures. It is fully
possible that the early death of the animals in acute exposures does not permit the development of those symptoms
which are observed in chronic irradiation. The increase in the biological effectiveness of neutrons-as compared
with electromagnetic radiations takes the form of a shortening of the times of appearance of the late effects of
irradiation. Thus, for example, at the ordinary level of neutron background (approximately 0.05 REP/day) the symp-
toms of cataract can be observed in persons working with neutron sources as early as the fifth or sixth year of
work.
For the "remote consequences of irradiation" a special criterion of biological effectiveness must be em-
ployed, which should be defined not by the ratio of the neutron and x-ray doses that cause the same effect, but
by some other mathematical quantity.
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In radiation chemistry and in radiobiology, the concepts of "incubation period" and "latent period" are
widely used. An adequate mathematical concept is the "expectation time," defined by the probability function
100
50
20
10
5
1
0 2 4
Mice
Neutrons
(E=140 Mev)
x- radian.
(E=ZOO key)
100
50
20
10
5
on
Rats
1
Neutrons x-radiation
(E=/40 Mev) -
(E=200 key)
8 10x fOtrgig 0 2
6 fox foe erg/g
Fig. 7. Survival of animals, as a function of doses of x-radiation and of
ultra- fast neutrons.
t = re c/ kT, which was very successfully used by SchrOdinger [12] to define the expectation time of spontaneous
mutations during normal functional activity of an organism. Here T corresponds to the order of magnitude of
the period of molecular fluctuations of the biological system, and c to the energy threshold that must be reached
during timer due to thermal motion with the energy kT. For warm-blooded animals (T = 308? K), kT =0.0267 ev,
1kT i
T = 1.5 ? 10-13 sec. According to Schrodinger, the function t = re E/s a measure of the improbability
that an amount of energy equal to E can accumulate by chance in some definite part of the system with a given
kT, and the factor T indicates that although the probability of accumulating the required amount of energy ?
is very small, it recurs "at each vibration," i.e., about 1013 times every second.
Radiation may affect the magnitude oft directly
transition, which becomes equal to e ? AE (where AE
alters the "characteristic frequency" of the system, i.e.,
this case the increase in v necessitates a reduction in T.
by lowering the energy threshold ? for an unfavorable
is the radiation energy received by the molecule); or it
1
= r, producing disintegration of the molecule; in
The use of the probability function of the expectation time to describe the kinetics of radiation sickness in
the latent period is entirely natural, since this function characterizes chain-type reactions, and the hypothesis of
self-accelerating chain reactions in radiation sickness is currently finding more and more experimental confirma-
tion [13].
Taking all this into account, we may consider That the reduction of the expectation time for unfavorable
molecular transitions depends not only on the size of the maximal or mean tissue dose of this or that radiation,
but also on the type of radiation. This explains the greater biological effectiveness of the chronic action of
heavy charged particles as compared with that of electrons. Since the rate of appearance of the terminal effect
of irradiation depends, in our opinion, on the constant action of thermal collisions of molecules, we can expect.
(other things being equal, e.g., with equal daily doses) that organism to go "out of commission" first in which
the radiation energy is localized in processes more profoundly affecting organic structures, and specifically, in
reaction with atomic nuclei. Primary physicochemical changes in organic structures under the influence of
radiation can take the form, for example, of single rupturings of the most "fragile" intermolecular bonds and of
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changes in molecular configurations. Then the frequencies of tautomeric transitions may increase, and the
properties of prototropic substances may be altered.* Very little energy is required for these transformations;
in comparison with this, the energy released in every ionization (approximately 30 ev) has the effect of the
strongest explosion; it is quite possible that a small excitation would be enough to initiate all these transforma-
tions. Somewhat more energy is required to bring about stereoisomeric transitions, and still more (on the order
of an electron-volt) for threshold isomeric transitions.
These physicochemical changes in living material lead to the distortion of many chemical processes, to
a change in the direction of these processes.
Simultaneously with chain ionic transformations and radical tautomerizations, to which radiation imparts
an irreversible character, under the influence of a heightened thermal disorder the formation of racemic mixtures
goes on in the optically active protoplasm. The protoplasm loses its asymmetry. Substances essential to life,
taking part in metabolism? proteins, carbohydrates, lipoids? which characteristically exist in the form of pure
optical opposites, suddenly begin to undergo racemization. The formation of a racemic mixture is thermo-
dynamically favorable, since this corresponds to the maximum entropy (disorder).
Continuing on the subject of the terminal effect, in establishing the maximum permissible dose it is
necessary to consider not only the effectiveness of the primary event of the reaction, but also the reduction in
the expectation time of harmful consequences, which is significantly reduced in neutron irradiation.
But as yet no observations are available of a sort that would make it possible to follow the accumulation of
harmful radiation symptoms from generation to generation. So it is common to take an expectation time! equal
to the average life span of a single generation. In this case, the biological effectiveness is connected only with
the physical properties of the radiation, with the special features of its reaction with the material.
The linear ionization density is taken as the physical factor that determines the biological effectiveness of
radiation exposure. In the general case, the biological effectiveness of nuclear particles at equal doses is a com-
plicated function of the beam intensity (I, cm-2? sec -1), linear energy losses of the particles (.9-, erg/cm), and
the cross-sectional area of the track (5, cm2). At higher intensities of radiation ("high background level"), where
superposition of the tracks occurs, the track cross section S apparently plays a lesser role. In this case the bio-
logical effect is proportional to the product I , i.e., the intensity of the radiation dose. At a "low background
level," .9- and S appear to play the chief roles. For equal intensities and radiation doses, it can be assumed that
the increase in the biological effect will be proportional to a certain quantity, equal to VS= 13/ , where
p is the track radius. The track radius formed in water by Compton- or photoelectrons is considered approxi-
mately equal to 15 mg (1.5.l0_6 cm), i.e., equal to the dimensions of organic molecules. Tracks formed by
the heavier particles (protons, a-particles, etc.) have larger radii. For the probability of injuries at equal dis-
tances p from the axis of the track, the relative effectiveness of two types of radiation can be taken equal to the
cube root of the ratio of their linear energy losses, i.e.,
OBE = = 7
41/42' (5)
The energy losses per unit path length in the tissue for various particles can be estimated on the basis of
concepts formulated by Rossi [14]. For any particles carrying unit charge and heavier than the electron, if only
energy losses due to collisions are considered, the relation between energy and path length of the particle in air
is illustrated by the very convenient curve
E/mc2= f (r/mc2),
where E is the kinetic energy of the particle, mc2 is the rest energy of the particle, and! is its range in air. For
any particle of charge Z, at energies roughly half the rest energy (E < 0.5 mc2), the following relation holds
between total path length and energy E:
-
(mc2) 4 2
0,51E1/4
Prototropic substances are tautomers with migrating protons.
(6)
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where Ei is the particle energy in Mev, ri is the particle path length in g/cm2 of air. This relation is directly
confirmed by the experimental data. Here the ranges ri in g/cm2 are expressed by Ei in Mev in roughly the
same way for tissue- like substances as for air. Consequently, Relation (6) can be extended to tissue with com-
plete justification.
This relation holds for electrons with energies up to 0.25 Mev and for protons with energies up to 500 Mev.
For heavier particles it obviously holds at even higher energies.
On the basis of Equation (6), the mean energy losses .9 per unit path length in the tissue will be given by
E.
= 96( mic2 )314 2
Ti Zi
Taking Expression (5) for 71 into account, (7) can be written
(7)
in- c2 1/4 (E / 1/4 ?'\2/3 (8)
m
71= )) ( Z 1 ic Z j ?
Since the choice of the "standard" with which all other forms of radiation are compared is very important
for the determination of relative biological effectiveness, and since electromagnetic radiation is usually taken
as a "standard," we shall examine the dependence of n on the energy of electrons. Let Est be the energy of the
electrons of the "standard," and E be the energy of the electrons in the region below 0.25 Mev, where Formula
Ect 4
(6) holds. In this case, ri - , i.e., n is inversely proportional to the fourth root of the electron energy.
In the same energy region (E < 0.25 Mev), the effectiveness of any other particle in comparison with the electron
is equal to ri = 6.65 A1/4 (Ee/Ei)1/4 Zi2i3 . Thus, for example, for the proton (A = 1; Z = 1) ii = 6.65 (Ee/E01/4 .
For a proton and an electron of equal energies, n = 6.65. The value of ?I .will be greater for heavier particles:
for a-particles, 2.24 times as great; for the carbon nucleus, 6 times; for the oxygen nucleus, 8 times.
The energy losses of electrons with energies > 2 Mev obey a more complicated expression than Formula
(6). In this region, beginning with 3 Mev, radiative losses are increasing, becoming equal to the ionization
losses at an energy of 150 Mev, and at 300 Mev comprising about 751 of the total energy losses of the electrons.
The harmful role of cascade processes in tissues has not been investigated, and therefore, in calculating ri for the
energy region above 150 Mev, especially for large objects (of the order of 30 cm), total energy losses must be
considered. For small experimental objects it is reasonable to take only ionization losses into account.
z
0.0!
0, I /,0
10
100
1000
Mev
Fig. 8.
Biological effectiveness of particles of various energies as compared
with electrons with an energy of 100 key.
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In Fig. 8, curves are set forth showing the dependence of ri on the energy of particles (electrons, and
?- mesons, protons, deuterons, tritons, a-particles, carbon nuclei, oxygen nuclei, and phosphorus nuclei), cal-
culated in relation to a 'standard" electromagnetic radiation with an energy of 100 key, in the energy interval
001 - 500 Mev, on the assumption that the harmful action is proportional to ir9.. The electron curve e shows
that at energies above the usual 100 key, we should expect a reduction in relative biological effectiveness to
0.75 (at energies of 1-2 Mev), and then an increase to 1 (at energies of 50-60 Mev). Values of the relative bio-
logical effectiveness of electromagnetic radiation, obtained in experiments at various quantum energies, are in
good agreement with calculated values for electrons. Thus, for example, it is observed that the OBE of brems-
strahlung of 20-23.5 Mev, energy compared with x-rays having energies of 180-200 key falls to 0.7-0.8. The
OBE of Co60 radiation, compared with 200 key x-rays, is from 0.7 to 0.8, which likewise does not conflict with
the following calculated data:
Particle
Theoretical OBE
Statutory OBE
Electron
Tr -meson
A- meson
Proton
Deuteron
Triton
a- particle
Lithium nucleus
Beryllium nucleus
Oxygen nucleus
1
3.8
4.1
6.6
7.8
8.6
14.7
19
28
52
1
10
20
The calculated OBE values can serve as a basis for the determination of the maximum permissible doses of
nuclear radiations of various type and energies, especially in the case of a multicomponent mixture of secondary
ionizing particles In neutron work. Thus, for example, for neutrons with a mean energy of 5.6 Mev, when about
90-95% of the dose arises from recoil protons CE" = 2.8 Mev) and 5-10% from recoil C, N, and 0 nuclei, we may
suppose that for the remote consequences, the coefficient of relative biological effectiveness will be of the order
of 6.9 ? 2.8 + 0.1.52 = 7.7 (compared to x-radiation of 200 key energy). Experiments on the acute irradiation
of dogs yield a coefficient of OBE around 3-4. Similarly, we may expect that the OBE for ultra-fast neutrons
will be in the neighborhood of 10-15 (because of the increase in dose, ktributable to recoil C, N, and 0 nuclei),
although the comparative study of survival of animals following acute irradiation points to a magnitude of OBE
equal to 1.8-2.0 (see Fig. 7).
For maximum permissible neutron fluxes in the energy interval 0.1 - 500 Mev, we assume the coefficient
of OBE of neutron radiation compared with/ x-radiation of 200 key energy to be equal to 10. Thus, the maximum
permissible daily dose is taken equal to 0.005 REP. In calculations, the maximal values of tissue doses (curve 2,
Fig. 5) W* max are used, expressed in Mev/g for 1 neutron/cm2. First the integral neutron fluxes producing a
maximal dose of 1 REP are calculated (1 REP = 93 erg/g = 5.8 -107 Mev/g). For this, the quantity 5.8-107 Mev/g
is divided by the appropriate ordinates in curve 2, Fig. 5. Then the result is multiplied by 0.005, to obtain the
maximum permissible daily neutron flux. Finally, the maximum permissible neutron flux for a 6-hour work day
(42-hour work week) is computed by dividing the maximum permissible daily flux by the duration of a work day
in seconds, i.e., by 6 ? 3.6 -103= 2.16 ? 104 sec.
The calculated values for the maximum permissible neutron fluxes are represented by the curves in Fig. 9.
There is no reason to expect a reduction of the coefficient of biological effectiveness for high-energy
neutrons. Spallation and star formation under bombardment with high-energy nucleons cause the production of
particles with a high linear ionization density, and give us occasion to consider the mechanisms by which injuries
to organic structures, attributed to individual particles, can become noticeably more frequent. For this reason,
it is recommended that the values cited in Fig. 9 be regarded as only a temporary, approximate solution of the
problem of the maximum permissible neutron dose. If we take the genetic effect of radiation into consideration,
then in calculating the expectation time for harmful mutations it is necessary to take! significantly greater than
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the mean time of one man's working in a factory, and perhaps, equal to the lifetime of several generations of
men. In this case, the doses quoted must be further reduced several-fold ? a conclusion to which radiobiologists
have recently inclined,
(Os
(08
lo?
106
to5
100
eutronsicm2 for 1 REP
S.
Neutrons/cm2 for 0.005 REP
10
1
cm2. sec for 0.005 ,REP during=
b hours
0,1 1 10 100 1000 Mev
Fig. 9. Number of neutrons per cm2 producing a maximum tissue
dose of 1 and 0.005 REP, and neutron currents in neutrons/cm2 sec
producing a dose of 0.005 REP over a 6-hour work day.
a) Neutrons/cm2 for 1 REP; b) neutrons/cm2 for 0.005 REP;
c) neutrons/cm2' sec for 0.005 REP during 6 hours.
LITERATURE CITED
[1] I.. Cohen, Phys. Rev. 81, 184 (1951).
[2] N. A. Vlasov, in the book: Neutrons [In Russian] (Gostekhizdat, 1955).
[3] Coll: Energy Levels of Light Nuclei [In Russian] (Izd. IL, 1952), p. 66.
[4] J. H. Tait, Brit. J. Radiology 23, 269 (1950).
[5] W. A. Mills and G. S. Hurst, Nucleonics 12, 4 (1954).
[6] J. A. Barr and G. S. Hurst, Nucleonics 12, 8 (1954).
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[7] J. Hadly, E. Kelly, et al., Phys. Rev. 75, 351 (1949).
[8] G. R. Mott et al., Phys. Rev. 88, 9 (1952).
[9] V. P. Dzhelepov and Iu. M. Kazarinov, Doklady Akad. Nauk SSSR 99, 939 (1954).
[10] V. I. Gol'danskii, Uspekhi Fiz. Nauk XI, 2, 234 (1950).
[11] W. Snyder and J. Neufeld, Brit. I. Radiology -28, 342 (1955).
[12] E. SchrOdinger, What Is Life 7 (Russian translation), (Izd. IL, 1947).
[13] B. N. Tarusov et al., Coll: Primary Physico-Chemical Processes in Radiation Sickness [In Russian]
(Medgiz, 1957), p. 25.
[14] B. Rossi, in the book: High-Energy Particles [In Russian] (Gostekhizdat, 1955).
Received December 23, 1957.
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SILICON PHOTOCELLS AS SOLAR-RADIATION CONVERTERS
V. S. Vavilov, G. N. Galkin and V. M. Malovetskaia
This paper presents the results of investigations into the properties of p-n junctions
obtained by the thermal diffusion of phosphorus into p-type silicon. Data are given on the
load and spectral characteristics of silicon photocells with p-n junctions, as well as on the
operation of these photocells at high intensities of illumination.
One of the methods of obtaining p-n junctions of large area in silicon is the thermal diffusion of admix-
tures of some elements. In a series of papers devoted to the problem of the direct conversion of solar energy
into electrical energy, photoelements are described which were prepared by the diffusion of boron into n-type
silicon 111 and of antimony into p-type silicon [2].
p-n junctions obtained by the thermal diffusion of phosphorus from the gaseous stage into p-type silicon
were investigated in the present work.*
Volt-Ampere Characteristics
The forward branch of the volt-ampere characteristic of p-n junctions are described by the equation
? J 0 [ exp (AqicUT) 1 ,
where J is the current flowing through the junction, U is the potential across the junction, Jo is the saturation
current, q is the electronic charge, and A is a multiplying factor which depends on U.
The resistence of the p-n junctions at the zero point Ro has a value of about 106ohm.There is no region
of "saturation current" on the reverse branch of the characteristic. This .branch becomes a straight line whose
slope corresponds to a constant resistance of approximately 101ohm. A considerable portion of the forward branch
is a straight line (Fig. 1). From the slope of this straight line it is possible to obtain a value for A which is con-
stant over a region of the characteristic. A as a function of the applied potential U is given in Fig. 2.
In real photocells operating at considerable current densities (about 20 ? a /cm2), the resistance in series
with the junction should be taken into account in the expression for the volt-ampere. characteristic. It is com-
posed of the resistance at the contact on the p-type silicon, the resistance of the thin n-type surface layer, and
the volume resistance which is usually small.
The region of the volt-ampere characteristic situated in the 4th quadrant represents the load characteristic.
Load characteristics were obtained for photoelements illuminated by a lamp with a filament temperature
of approximately 3100? C and a water filter 1 cm thick. The illumination intensity was chosen so that the value
* The techniques of obtaining p-n junctions by the diffusion of phosphorus into p-type silicon and the manufacture
of photoelements were passed on by the authors to the All-Union Scientific Research Institute of Current Sources
(VNIIT) and were developed further by A. P. Landsman, A. K. Zaitseva, and A. Ia. Gliberman. Solar batteries
made at the VNIIT in 1957 have an efficiency of-5-67o, while individual elements have an efficiency of up to
8%. 14-cell batteries with a working area of about 22 cm2 produce a voltage of 5.5 v at a current of approxi-
mately 20 ha. ?
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of the short-circuit current is the same as for illumination of the photocells by solar radiation with an energy
flux of 100 Mw/cm2. Measurements were made in a vacuum thermostat in temperature intervals of 0 to + 95? C
and ? 75 to + 90? C with photocells prepared from silicon with a resistivity of 25, 4, and 0.4 ohm cm. The load
characteristics of one of the photocells at temperature of 22, 60. and 94? C are given in Fig. 3. From the graphs
it can be seen that the short-circuit current decreases by approximately 10-15% with a decrease in the tempera-
ture.
1,5
fo-1
too 200 tho tho Er, my
Fig. 1. The forward branch of the volt-ampere
characteristic of a nonilluminated silicon photo-
cell.
As the temperature decreases the emf in-
creases considerably, while with increasing tem-
perature the emf falls according to a linear law
which is close to the theoretical dependence [3]
for the given temperature interval. With an in-
crease in the resistivity of the silicon from which Fig. 3. The volt-ampere characteristics of an illu-
the photocells are made, a fall in the emf and minated photocell at different temperatures.
an increase in the slope of the straight line in
Fig. 4 are observed.
From the shape of the load characteristics extrapolated to zero series resistance it follows that for the most
favorable construction and for a sufficiently high value of the ratio J5../Jo [41
1)-0,8U0 Js.c.
From this it follows that the temperature dependence of the efficiency of the photocells is mainly determined
by the temperature dependence of the emf.
Spectral Characteristics
The curves showing the dependence of the collection factor a on the wavelength A. we will call the
spectral characteristics of photocells with a p-n junction. The collection factor is the ratio of the carrier flux
through the junction when the photocell is short-circuited to the total number of electron-hole pairs generated
by light per unit time in the semiconductor.
2
100 200 300 400
500 600 IT) triv
Fig. 2. The dependence of A on U (the numerals on
the curves refer to the photocell numbers).
94?C 60?C 22?C
-400 -300 -100 -100 0 100 200 300 00 500 U
ma
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uo , mv
600
20
10
22
2,4,5
-80 -60 -'0 -20 0 20 40 60 80 100
t,?C
Fig. 4. The dependence of the silicon-photocell emf
on the temperature (the numbers on the curves refer
to the number of the photocell).
a
0.4
0,2
0,7 0.8 0,9 , 1,0 Id
R,
Fig. 5. The spectral characteristics a(x) of photo-
cells with p-n junctions at various depths:
2 g (curves 1, 2); 9 g (curve 3), and 15 g (curve
4). Curve 5) characteristic of the same cell as for
curve 1 after the removal of the film which lowers the
the coefficient of reflection (the short-circuit current
after the removal of the film fell by 21% as the
result of an increase of the coefficient of reflection
from 12 to 36%),
The spectral characteristics of photocells with
p-n junctions at a depth of 2 g (curves 1, 2, and 5),
9 ? (curve 3), and 15 g (curve 4) are given in Fig.
5. From the graphs it can be seen that photocells
with junctions situated close to the surface have the
best spectral characteristics. The true value of the
reflection coefficient of the semiconductor surface
has to be used in the calculation of the collection
factor a, It has been shown that the reflection co-
efficient of an etched silicon surface falls from
36% at x =0.4 p to 30% at x =1.1 p. An
unetched silicon surface subjected to phosphorus
?
diffusion from the gaseous phase has a reflection
coefficient of about 12% at x =0.4 - 0.75 p.
ce
Experimental curve
48
Of CC 2
/
/
//---, /
0,4 I/ N., ,/
0,6
/ ).,
,I / .
// / ...
/
,2 I/ / ...?,
/
/ . .
/
0,8 49 1,0 1,1
) g
Fig. 6. Comparison of the spectral characteristics
of photocells with a p-n junction at a depth xs =
= 2.10-4 cm with the spectral characteristic cal-
culated from the following data:
xs = 2.10-4 cm, s =104 cm/sec, D = 2 cm2iv ? sec,
= 2.10-4 cm, L = 25.10-4 cm ; ) collection
factor for the holes liberated by light in the surface
n-type layer ; a2) collection factor for electrons
in the p-type region.
The comparison of the curves a( X) for the
same cells with a natural transmitting film (curve 1)
and without it (curve 5) shows that the film exerts
only an insignificant influence on the value of the collection factor, while at the same time it can appreciably
(by up to 20%) increase the number of electron-hole pairs produced and consequently raise Js.c and the efficiency
of the photocell.
A general expression for the collection factor when carrier pairs are produced by light on either side of the
p-n junction, with surface and voluine recombination taken into account, was used for the theoretical interpreta-
tion of the spectral characteristics, The latest data on the coefficient of absorption of light in silicon led to the
conclusion that when the depth of the junction is less than 2 g, the absorption of light in the infrared region and,
consequently, most of the pair production takes place throughout the bulk of the silicon below the p-n junction.
A comparison of the experimental characteristic a(X ) for a photocell with a junction at a depth of 2 ? with the
characteristic calculated from the equations given in [5] is made in Fig. 6.
The theoretical curve has been calculated by fitting to the experimental one. The depth of the p-n
junction, equal to 2 p, has been calculated from the known features of the diffusion process. The diffusion
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length L in p-type silicon lies between the values 20 and 34 ? obtained from independent measurements: the
first by a drift method, the second by a diffusion method [6]; the value of the surface-recombination velocity
according to our estimates is 104 cm/sec ? 50%, The most arbitrary choice made is the value of the diffusion
length for carriers in p-type silicon. The diffusion
coefficient has been calculated from the data given
in the literature on the mobility in highly alloyed
silicon [7]. Additional experiments on the deter-
mination of the mobility and the diffusion lengths
in silicon alloyed with phosphorus will make it
0,4
possible to predict more accurately the shape of the
spectral characteristics and, consequently, also the
efficiency of silicon photocells.
In view of the high cost of silicon, the question
of the concentration of light on to the photocell by
means of mirrors or lenses and the increase of the
useful power obtained from 1 cm2 is of considerable
interest. Preliminary data on the operatiOn of silicon
photocells at a light flux of up to 0.7 w/cm2 (approxi-
mately seven times the value of the solar-energy
flux) were obtained in our laboratory by A. V. Spitsyn.
A lamp with a water lens, which was also used as a
filter, served as the radiation source. The tempera-
ture of the filament was maintained within the
limits 20 ? 3? C. A series of characteristics of one
photocell is given in Fig. 7. As the intensity of the incident radiation increases, the following main features are
observed: a) there is a very small increase in the emf; b) Js.c increases considerably, the increase being
linear up to almost 0.5 w/cm2; c) there is a fall in the efficiency starting from 0.1 w/cm2 due to the change
in the series resistance; d) the series resistance itself decreases, which can be explained by a modulation of the
conductivity of the n-type layer.
20 40 60 80
1. ma
Fig. 7. Load characteristics of a silicon photocell
at high illumination intensities. 1) Pi = 0.1 w/cm2;
2) Pi = 0.2 w/cm2; 3) Pi = 0.3 w/cm2; 4) Pi =
= 0,38 w/cm2; 5) Pi = 0.53 w/cm2; 6) Pi =
=0.7 w/cm2.
SUMMARY
The results given lead us to conclude that photocells of p-type silicon with a p-n junction, obtained through
the thermal diffusion of phosphorus, can be used as converters of solar-radiation energy.
The following properties of such photocells have been observed:
1. The current in the external circuit is produced by light through the formation of electron-hole pairs
both in the n- type region containing phosphorus, as well as in the p-type region below the p-n junction.
2. The diffusion length in the p-type region after the setting-up of the p-n junction falls to 20-35 i.
3. The surface film formed during the thermal diffusion of phosphorus lowers the reflection coefficient
in the most important spectral region from 30-36% to 12-15% and does not appreciably lower the collection
factor cc , as a result of which the short-circuit current increases by comparison with photocells with an etched
front surface.
4. A solar-energy flux of up to 0.5 w/cm2 can be utilized efficiently with the photocells investigated.
When the temperature of the photocells is maintained at 25? C (by the removal of heat), 150 Mw of electric
power can be obtained from 1 cm2 of photocell working surface.
The authors express their thanks to Corresponding Member of the Academy B. M. Vul for constant attention
and advice, to V. K. Subashiev for a number of valuable remarks, and also to laboratory associates V. G.
Kolotilova, B. Ia. Iurkov, B. D. Kopylovskii, lu. A, Kolotov, and V. M. Vasin, who in many respects have
assisted in the carrying out of the work. Engineer Re Sh. Akchurin and laboratory technicians L. V. Belova,
E. M. Divirkovskaia, and F. M. Sidorov took part in the work.
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LITERATURE CITED
[11 D. Chapin, C. Fuller, and G. Pearson, Bell. Lab. Rec. 33, 7, 241 (1955).
[21 Iu. P. Maslakovets, G. B. Dubrovskii, S. A. Poltinnikov, and V. K. Subashiev, J. Tech. Phys. (USSR)
26, 2396 (1956).s
[3] R. Cummerov, Phys. Rev. 95, 1, 16 (1954).
[41 V. K. Subashiev, Semiconductor Solar-Energy Converters [In Russian]
and Technical Propaganda, 1956).
[5] W. Pfann and W. Van Roosbroeck, J. Appl. Phys. 25, 1422 (1954).
[6] L. S. Smirnov, J. Tech. Phys. (USSR) 27, 11, 2469 (1957).*
[7] G. Backenstoss, Phys. Rev. 108, 6, 1416 (1957).
Original Russian pagination., See English translation.
(Leningrad House for Scientific
Received December 14, 1957.
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RADIOACTIVE CARBON FROM NUCLEAR EXPLOSION AND
NONTHRESHOLD BIOLOGICAL EFFECTS
A. D. Sakharov
1. Introduction
When any nuclear weapons are exploded, including the so-called "clean" (fissionless) hydrogen bomb,
a very large number of neutrons enter the atmosphere (see Section 2) and they are 'hen captured by atmospheric
nitrogen according to the reaction
n +N" ?> p + C"
which gives rise to long-lived radioactive C. This radioactive carbon enters human tissue, where it decays,
causing radiation damage, with a dose of 7.5? 10-4 r per megaton burst (see Section 3).
I shall make the following assumptions to evaluate the harm to humanity due to the production of radio-
active carbon.
1) The human population in the next few thousand years will be thirty billion persons.
2) A dose of 1 r to the reproductive glands leads to hereditary diseases in 10-4 cases (see Section 4).
3) Other nonthreshold biological effects triple the number of cases (see Section 4).
The total number of radiocarbon victims from a megaton burst is found, on the above assumptions, to be
6600 persons. This number is spread over a period of the order of 8000 years. According to Leipunskii's data [ii,
nonthreshold biological effects due to radiostrontium and external radiation due to radiocesium increase the
number of cases by a factor of 1.5, the cases occurring in our generation and the one following. The total number
of cases due to nuclear tests which have already been performed (50 megaton energy) is estimated at 500,000
persons. This would seem to be a conservative estimate. One cannot eliminate the possibility that the total
number of cases is already one million persons and is yearly increased by 200-300 thousand persons.
Continued testing and all attempts to legalize nuclear weapons and testing cannot be reconciled with
humanity or international law. Because the so-called "clean" (fissionless) bomb is radioactively harmful, there
is absolutely no ground for the propagandistic assertions concerning the particular qualities of this instrument of
mass destruction.
2. Neutron Formation in Nuclear Bursts
In an atomic (fission) explosion each act of fission is accompanied by an increase in the number of neutrons
by a factor of v ? 1 (where v is the number of neutrons produced per neutron captured in fission). An insignificant
number of the neutrons produced are captured by the surrounding material (with formation of plutonium). We
assume that in each act of fission (at 180 Mev) the number of neutrons produced i xi ? 1 = 1.5. In military ter-
minology one usually describes the energy of a burst in terms of the equivalent mass of TNT. A burst of 1 megaton
TNT equivalent corresponds to the fission of 60 kg of uranium or plutonium, with the emission of 2.25? 104
neutrons.
There are two different types of pure thermonuclear bombs, namely those which use liquid deuterium and
those which use the chemical compound of deuterium with the light isotope Li6. The first of these bombs
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produces many more neutrons per unit energy. We shall, however, restrict our considerations to the second,
since it would seem that it is just this type of bomb which is at present receiving most attention. The funda-
mental reactions taking place in this bomb are
D D He3 + n;
(1)
(2)
n+ Li 6 --> He4 +1-13;
(3)
1-13 + D --> He4 n.
(4)
The effective probability (that is,the product of the cross section by the rate of reaction)for Reactions (3)
and (4) is about one hundred times as great as that for Reactions (1) and (2).
Most of the energy of the burst comes from the "fast" Reactions (3) and (4). These reactions aid each
other, and together they leave the total number of neutrons and tritium nuclei invariant. The "slows-Reactions-
(1) and (2) serve as the initial neutron and tritium sources.
A detailed investigation of the kinetics of the Reactions (1) - (4) shows that when the Li6 is sufficiently
burned out, one cycle of Reactions (3) and (4) leaves about 0.2 neutrons and 0.2 tritium nuclei which arise as
a result of (1) and (2). In this cycle 22 Mev of energy is liberated, which means that one neutron is liberated
180 Mev
per 110 Mev of burst. This number is very close to the figure 1 5 -120 Mev for an atomic burst.
.
In a hydrogen bomb surrounded by a uranium shell, a large amount of the energy results from fission of
U 238 by fast neutrons from Reactions (4) and (1). Since, however, the number of neutrons per unit energy is
almost the same for a pure atomic and a pure thermonuclear burst, we may say that in this case also we get
2.25-1026 neutrons/megaton.
3. Calculation of the Radiation Dose
We shall use experimental data [2, 3] referring to natural CU. Cosmic rays cause many kinds of nuclear
reactions in the upper layers of the atmosphere, and one of the products of these reactions is neutrons at the rate
of 2.6-2.4 neutrons/cm2.sec. After being slowed down, about 95% of these neutrons are captured by atmos-
pheric nitrogen, forming C" according to the reaction
(n + p + C14).
The half-life of C14 is 5570 years. Even in biochemical processes, C14 is chemically very similar to
stable carbon. During this lifetime the Cm concentration reaches equilibrium with the stable carbon of the
so-called exchange reservoir, that is,atmospheric carbon in the form of CO2, carbon in rivers and ocean waters
in the form of soluble compounds, and finally carbon in living organisms. For natural C14 this concentration
has been measured experimentally. In 1 gram of natural carbon of the exchange reservoir there take place
0.25 decays/sec, which corresponds to 6.1016 atoms of CI4 per 5.1022 atoms of C12. The surface area of the
earth is 5.1018 cm2. We find that the probability for decay of a single C14 nucleus formed in the atmosphere
0.25
per gram of carbon of the exchange reservoir is
2.6.5.1018 ? 2.10-2? per gram.
We shall assume that the geochemical environment of the earth will not change significantly over the
next several thousand years. Then the decay probability per gram of carbon which we have obtained for natural
CJos is good also for carbon nuclei formed at present in nuclear bursts.
This same statement can be phrased in terms of linear equations. Every solution of a set of linear equations
(with independent variables x and t) whose right side is q(t) at the point x = 0 can be expressed by a superposition
of singular solutions of the following type :
Singular solution
758
source 6 (x) (t ? to),
solution n (x, T), T t ? to
(here n is a Green's function)
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Superposition
source
solution AT (x, t
In the special case of a steady source qo at the point x = 0, the solution at x = xo is
N (x0) qo n (xo, s)ds, i.e.,
0
Siids =- -?N
qo
In our case x denotes the coordinates of points in the exchange reservoir, and x = 0 denotes the upper layer
of the atmosphere; qo = 2.6 neutrons/cm2- sec ? 4tr R2; No = 0.25 decays/sec-gram; R = 6.3-108 is the radius of the
earth; n (x0, t? to) is the number of decays per gram of natural hydrogen per second at the point; at time t
divided by the number of C14 nuclei produced in the atmosphere at time to.
We then obtain S Mt. 2 Jo 2" per gram.
For a 1 megaton burst we obtain 2.25. 1026? 2-10-2? = 4.5.106 decays/megaton-g.
We shall express the radiation dose in roentgens, setting a roentgen approximately equal to a rad which
we take as the dose that will produce 100 ergs of ionization energy per gram of tissue.
The maximum energy of C" 8 -decay is 0.154 Mev. about two-thirds of which is carried away by a
neutrino. Thus about 0.05 Mev is liberated in the tissues, or 8 ? 108 erg /decay.
Assuming further that carbon makes up about 18% of the weight of the body, we find the total energy
liberated per gram of tissue from a 1 megaton bomb to be
0.18 4.5 - 106- 8 - 10-8 = 7.0.10_2 erg/g = 7.5 .1p-4 r.
The data are not as gobd when we come to the time distribution of the decay, that is, on the form of the
function n (x0, t). Using Anderson's [2] estimate of 8.5 g/cm2 for the mass in the exchange reservoir, we can
assume that within this reservoir equilibrium is attained in a time short compared with the lifetime of q14, and
that the C14 leaves the reservoir at an insignificant rate. On these assumptions the time dependence of the decay
will be an exponential of the form exp ( ).
8 thousand years
4. Nonthreshold Biological Effects of Radiation
A thermonuclear war involves the potential danger to all of humanity of being subjected to a lethal
radiation dose (about 600 r). This danger would not seem to exist in testing nuclear arms, since at the present
rate of testing the dose per person is never greater than a roentgen. However, billions of persons are subjected
to this dose in addition to the natural background, and will be so subjected (in the case of C14) for several hundreds
of generations. The amount of sickness caused by this additional radiation from testing under these conditions is
found from the so-called nonthreshold biological effects. The number of cases is proportional to the total dose
for all of humanity (that is to the dose in roentgens per person multiplied by the number of persons) independent
of the distribution of the radiation over the population or of its time dependence.
The simplest nonthreshold effect of radiation is hereditary [4-6]. The substance which transmits heredity
is the gene, a special structure in the chromosomes of cell nuclei. For an irreversible change of a gene (a so-
called gene mutation) a single act of ionization is sufficient, so that genetic changes can occur as a result of the
weakest radiation doses with a probability which is exactly proportional to the dose.
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Each gene is in a certain sense a letter in the biochemical program of the development of an embryo.
Therefore a change in one gene may in certain cases (for dominant mutations or accumulation of mutations)
lead to very significant hereditary changes.
At the present time human births involve about 2% hereditary diseases (schizophrenia, hemophilia, diabetes,
and many others) caused by mutations. The number of actual mutations is less than this, since some people with
hereditary diseases reproduce, and a single mutation may give rise to effects over several generations. This does
not, however, destroy the proportionality between the number of mutations and the number of hereditary sicknesses.
According to presently accepted ideas based on Meller's experiments with mice, 5% of mutations, and therefore
also of hereditary sicknesses, results from natural radioactivity (10 r over a human life of sixty years). Collecting
all these figures, we obtain the coefficient whichgives the increase of hereditary sickness due to radiation, namely
0.02.0.05 -4
- 10 per roentgen.*
10
The mean human population during the time it takes the C14 to decay will probably be about 30 billion
persons (about 10 or 11 times greater than at present). This estimate is not incompatible with increases in the
earth's productivity as science progresses.
Using this figure, we obtain (for radioactive carbon alone) 3 ? 10" ? 10-4 ? 7.5 ? 10-4 = 2200 cases of here-
ditary sickness from a megaton bomb, or 110,000 cases from all the tests already carried out. We are assuming
that the tests already performed add up to fifty megatons.
In animal and plant life mutations sometimes give rise to more advanced biological forms. It is conceivable
that human mutations (and hereditary sickness) should also be welcomed, since they may be considered a necessary
evil in the biological progress of the human race. Actually, however, human nature now changes primarily because
of social factors. We are inclined to consider uncontrollable mutations merely as an evil, and experiments with
nuclear weapons as being merely an additional cause for the death of tens and hundreds of thousands of persons.
Another example of nonthreshold biological effects of radiation is the possible increase in the amount of
cancer [7] and leukemia.
It has been shown experimentally that the cancerogenic effects of various nonradiational cancerogenic
substances are additive. There is no reason to believe that the active radicals which arise as a result of ioniza-
tion will behave in a qualitatively different way. Therefore, the increase in the amount of cancer, or equivalently,
the drop in the age at which cancer occurs, will be a linear function of the dose to which humanity is subjected.
The total coefficient for all types of cancer and leukemia is taken to be of the same order of magnitude as that
for genetic damage, namely 1- 2.10-4 cases/r. Partially verifying this coefficient are data on the frequency of
leukemia, a professional disease of radiologists and in some sense related to cancer, The effect of radiation on
this disease is easy to study, since it occurs infrequently in nature. A dose of a single roentgen in a year gives
rise to additional leukemia fatalities at the rate of 2 -10-6, and over a thirty year lifetime this becomes 6 -10-5.
This coefficient is of the same order of magnitude as that suggested for other forms of cancer.
A .possible (though not experimentally proven) nonthreshold effect of radiation is a drop in the immUno-
logical reactions of the organism. In all probability premature aging and death is also a nonthreshold effect.
The mean life expectancy of medical radiologists (who are subjected to an average dose no greater probably
than 1000 r) is five years less than that for the general population. This means that premature death may occur
at the rate of 10-4 per roentgen.
Further, we should perhaps note that although mutations are not desirable in the human race, for viruses and
bacteria they may greatly increase the chance of survival. Examples are the mutation which occurred in diphtheria
in the middle of the 19th century and the periodic flu epidemics that affect a large part of the world's population.
* As in the case of Section 3, the use of the expressions for the steady-state natural process gives a proper in- ,
tegral over time, but no information on the decay law for an instantaneous source. Recessive genes may require
dozens and even hundreds of generations before they make their presence felt.
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It is difficult to evaluate this effect, although it is plausible that it is just as harmful to human health as is the
genetic effect.
On the whole,'according to our/approximate and probably conservative' estimate, the loss of human life
from all nonthreshold biological effects is at least three times that for the genetic effects alone, which means
a rate of about 3.10-4 per roentgen. Summing of all the above effects (without deductions for "vagueness")
gives 6? 10 per roentgen.
Thus the radiocarbon from the tests which have already taken place will affect about 330,000 persons. As
is well'known, an important factor is the fallout of radioactive strontium and cesium. Using Leipunskii's data
[1] we may estimate that the bone damage due to strontium and the external effects of cesium are about 0.5 of
the C" effect. For the sake of completeness, we shall give a brief description of the corresponding calculations.
If tests are to continue at the present level (that is 10-15 megatons/year) the radioactive strontium concentration
in the bones will be about 65 strontium units (lip C/g of calcium) which means that the radiation dose will be
160 ?lCs r per year or 1-1.5 ? 10-2 r/megaton. This dose causes sickness at about half the rate of the 7.5.10-4
r/megaton for the radiocarbon, since it involves a population of about 2.5 billion people (giving the factor 1/12)
and involves only the skeleton, which gives the factor 1/3. The effect of external y -radiation due to cesium is
of the order of 10-3 r/megaton, and taking into account the smaller population, this leads to an effect which is
about 10% of CIA effect. Thus, the total losses from a 1 megaton burst are about 10,000 persons, and the total
losses from all nuclear bursts to date are about 500,000. This is a conservative estimate, and if we were to in-
clude other radioactive isotopes, other kinds of. radioactive damage, and a more complete calculation of all
threshold and nonthreshold biological effects we would obtain a larger figure. We cannot exclude the possibility
that the total number of victims is already approaching 1 million persons, and that each year continued testing
increases this number by 200-300 thousand persons.
What moral and political conclusions can be drawn on the basis of the above figures I
One of the arguments presented by those who maintain the theory that tests are "harmless' is that cosmic
rays lead to doses which are greater than those from the tests. This argument forgets that we are adding to the
world's toll of human suffering and death, the suffering and death of hundreds of thousands additional victims,
including some in neutral countries and in future generations. Two world wars have also added less than 10%
to the death rate of the 20th century, but this does not make war a normal phenomenon.
Another argument which is found in the literature of several countries is, in effect, that the progress of
civilization and new technological advances have in many other cases led to human suffering. As an example,
comparison is often made with automobile accidents. But this analogy is not valid. The automobile raises
human living standards and leads to accidents only in individual cases as a result of carelessness on the part of
persons who are then legally responsible. The suffering caused by the tests, however, follows immutably from
each burst. To the present author it seems that all of the moral implications of this problem lie in the fact that
the crime cannot be punished (since it is impossible to prove that any specific human death was caused by radia-
tion) and in the defenselessness of future generations against our acts.
The cessation of tests will lead directly to the saving of the lives of hundreds of thousands of people and
will have the more important indirect result of aiding in reducing international tensions and the danger of
nuclear war, the fundamental danger of our age.
The author takes this opportunity to express his gratitude to 0. I. Leipunskii for valuable discussion.
LITERATURE CITED
[1] 0. I. Leipunskii, J. Atomic Energy (USSR) III, 12, 530 (1957).*
[2] E. C. Anderson, Annual Rev. Nucl, Sci. 2, 63 (1953).
[3] W. F. Libby, Radiocarbon Dating,(University of Chicago Press, 1955).
[4] H. J. Oilier, Acta radiol. 41, 5 (1954).
[5] N. P. Dubinin, Radiation and Human Heredity [In Russian] (manuscript).
* Original Russian pagination. See C. B. Translation.
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[6] S. N. Ardashnikov and N. Sthapiro, On the Possible Effect on Man's Heredity of the Increased Radiation
Level Due to the Tests of Atomic Armaments [In Russian] (manuscript).
[7] Biological Hazards of Atomic Energy (ed. Gliicksmanb), (Clarendon Press, Oxford, 1953).
Received July B. 1958
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LETTERS TO THE EDITOR
THE FIRST DISCOVERY OF COFFINITE IN THE USSR
Ia. S. Filipenko
A number of papers published in the U.S.A. [1-5] have reported a newly discovered silicate of uranium,
called coffinite U(SiO4)1...x(OH)4x. According to these papers coffinite is found in hydrothermal and sedimen-
tary deposits. Some of the deposits are important economically. The published reports describe chiefly the
coffinite from sedimentary deposits. Discoveries of this mineral have not been reported in Soviet literature.
TABLE 1
Comparative Data on Interplanar Distances and on
Intensities of Lines of Coffinite and of the Newly
Discovered Mineral
Investigated
mineral
Coffinite from the
Arrowhead mine
hid
d
A
1
hkl
d
A
I
011
4,67
9
011
4,66
strong
200
3,86
5
_
?
?
200
3,51
10
200
3,47
strong
121
2,184
4
121
2,78
weak
112
2,665
9
112
2,64
moderate
220
2,455
5
220
2,46
very weak
031
2,189
8
031
2,18
weak
013
2,002
7
013
2,01
very weak
321
1,855
3
321
1,841
weak
312
1,813
9
312
1,801
moderate
?
?
?
123
1,787
weak
400
1,742
4
400
?
,--
411
1,632
5
411
1,629
very weak
004
1,562
5
?
?
?
?
?
?
420
1,556
very weak
332
1,449
2
332
1,451
p
024
1,430
2
024
1,435
D
431
1,373
3
?
__
__
224
1,319
3
?
__
__
162
1,256
4
?
?
044
1,162
5
?
?
?
244
1,104
5
?
1,004
1
?
?
?
552
0,944
4
?
?
624
0,900
3
__
__
?
0,8813
3
__
__
__
its natural state gives
The present note describes a coffinite-type
mineral studied by us in 1956. It was found in
fractures in granite at depths of 33, 48, and 90 m,
occurring in small lenses and nests with irregular
form that range from 2-3 to 6-8 cm in long dimen-
sion. In all these occurrences the mineral is closely
associated with pyrite, galena, and more rarely,
chalcopyrite (see Figs. 1 and 2). Small grains of
transparent quartz are also commonly found in
association. In order of formation, the coffinite
preceded the galena.
Megascopically this mineral is brownish black,
with a cryptocrystalline structure and an irregular,
almost conchoidal fracture, The surface of the
mineral is dull. Its streak is brownish black. The
hardness is 68-131 kg/mm2, or 2.9-3.1 on Mohs'
scale. The mineral polishes poorly. A bead, fused
with NaF, fluoresces clearly in ultraviolet light.
Outwardly the mineral resembles hydrated pitch-
blende; in reflected light it is gray, with yellow-
brown internal reflections. Anisotropy is not re-
cognizable; the reflectivity of the mineral is lower
than that for sphalerite: R = 5.6- 7.5.
Because the mineral occurs in such small
segregations,a pure specimen is very difficult to
obtain. In conducting spectral, x-ray, and micro-
chemical studies, we selected approximately 100 mg
of comparatively pure mineral from each of two
samples.
r '
The x-ray study showed that the mineral in
a diffraction picture of a crystalline substance identical to that for the coffinite described
in the U.S.A. An analysis was made by' the powder method, the exposure being made in unfiltered radiation at
a potential of 40 kv and a current strength of 16 amp for 2 hours in a camera with a diameter of 57.3 mm. The
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Fig. 1. Coffinite (1) with disseminated grains of quartz (2) and a veinlet
of galena (3). Polished section of a sample taken from a depth of 33 m
(x 110).
Fig. 2. Inclusions of pyrite (1) in coffinite (2). Polished section of a
sample taken from a depth of 48 m (x 110).
film was measured on a comparator with a precision of ? 0.05 mm, and this permitted the interplanar distances
to be determined with an accuracy of 0.5% ford from 4 to 2 A and an accuracy of 0.1% ford below 2A.
The intensities of the lines were evaluated visually on a 10-division scale. For precision in the evaluation,
a photograph was taken of the samples with an internal standard (NaC1).
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The analyses established the fact that the mineral has a crystalline structure like zircon and is in the
tetragonal system; after indexing the reflections, the dimensions of the unit cell were determined by a Hull
(Hull-Davey) graph: a = 7.01, c = 6.26 f 0.01 A.
TABLE 2
Results of Spectral Analysis of Coffinite
Si
Al
Ca
Fe
Mn
Ni
Co
AvpAIIIMMM
Ti
V
Cr
Mo
Zr
Hf
Nb
Elements
To
Cu
Pb Ag
Sb
ei
An
Zn
Mean.ng of symbols
?nene M trace 11111 little present Eabundant M very abundant > 1%
-
-0.001% -0.01% 0.1% -1%
In the papers [1], [2], and [5], coffinite is also described as tetragonal, with a = 6.94 and c = 6.31.
On comparing the results of the x-ray study made by G. A. Sidorenko with the data in the papers [1],
[2], and [5], it was discovered that, in the main, the interplanar distances and the line densities agree (see
Table 1).
Spectral data are shown in Table 2 and a microchemical analysis, made by V. E. Pankova, is given in
Table 3.
TABLE 3
Results of Microchemical Analysis of Coffinite
Oxides
Depth
to mineral
occurrence, m
ooa
1702
s
sio2
Foa
A.1203
cao
MgO
Na20
? H2O
Total
at t=800?C
33
17,63
20,05
0,0
23,92
2,51
17,88
1,91
1,34
-
7,86
99,10
1
at tII00?
48
9,50
27,66
3,79
31,17
6,34
12,53
1,47
0,94
0,63
5,91
99,59
The chemically analyzed material could not be obtained pure, because it was contaminated with pyrite,
quartz, iron hydroxides, and, possibly, decomposition products of feldspar (sericite, kaolinite, etc.) inasmuch as
the mineral occurs in clay gouge.
This cited material furnishes grounds for considering the investigated mineral to be identical to coffinite.
LITERATURE CITED
[1] A. D. Weeks and M. E. Thompson, U. S. Geol, Surv. Bull. 1009-B, 31 (1954).
[2] L. K. Stieff, T. W. Stern, and A. M. Sherwood, Amer. Mineralogist 41, 9-10, 675 (1956).
[3] R. Zitting et al., Mines Mag. 47, 3, 53 (1957).
[4] E. B. Gross, Econ. Geol. 51, 7, 632 (1956).
[5] C. Frondel, D. Riska, and J. W. Fronde', U. S. Geol. Surv. Bull. 1036-G, 1 (1956).
Received January 21, 1958
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THE LIGHT ISOTOPES OF TELLURIUM
M. Ia. Kuznetsova, V. N. Mekhedov,
V. N. Rybakov, and V. A. Khalkin
In the work reported here an attempt has been made to determine the mass numbers and half-value
periods of the tellurium isotopes with A < 118 from their daughter products, and also to establish the nature of
the radiations from these isotopes.
The light isotopes of tellurium were produced by bombarding metallic antimony by protons from the
synchrocyclotron or the Joint Institute of Nuclear Studies. The irradiated target was dissolved in a mixture of
hydrochloric and nitric acids, and 10-15 mg of tellurium, selenium, and tin was added to the solution. After
the excess nitric acid had been driven off, the selenium and tellurium were precipitated with sulfur dioxide
from 3 M HC1. The precipitate was dissolved, and the selenium was driven out by sending HBr through the
solution. The tellurium was then precipitated again with sulfur dioxide.
To eliminate radioactive contaminations we used precipitation of Fe(OH)3 from an ammonia solution.
The filtrate was acidified with hydrochloric acid, and the tellurium was precipitated again with SO2, and was
finally purified by subliming the metal at 600-800? C in a stream of hydrogen. The condensate was washed
out with a few milliliters of concentrated hydrochloric acid containing Br2. Part of this solution (approximately
0.05 ml), dried on a filter paper, was used for direct measurements of the half-value periods and types of
radiation of the light isotopes of tellurium.
The daughter products (isotopes of antimony) were separated from the parent element by extraction in
di-isopropyl ether from 8 M HC1 containing Br2.
The extract was washed with 8 M HC1, and the ether was driven off from a 3 M solution of HC1. The
tellurium impurity in the resulting preparations did not exceed 0.2%. The separation of the daughter products
was carried out for 12 hours at intervals of 1.5 hours. The radioactivity of the preparations was measured with
an end-window counter MST-40. To determine the K-capture branching ratio,the radiation of some or the
targets was subjected to additional study with a magnetic analyzer [1]. The energy of the positron radiation
was determined from the absorption in aluminum.
The measurements gave the following results. The total decay curve of a radioactive preparation of
tellurium consists of three components, corresponding to the following half-value periods: approximately 17
days (Te121, K), approximately 6 days (mixture of Te118, K and Te 119, K) [2], and, finally, a period approximately
2.5 hours. According to [3] this last period should be assigned to Te117, which emits positrons with energy 2.5
Mev. The analyzer measurements showed, however, that about 75% of the radiation decaying with this period
consists of x-rays. Furthermore, the energy of the positrons is somewhat higher (2.7 Mev).
The total decay curve of the antimony isotopes produced in the decay of the light tellurium isotopes also
was found to consist of three components. The corresponding half-value periods are: 15 minutes, 2.8 hours, and
about 6 days. The last period is in all probability due to slight contaminations ( < 0.2%) of the daughter pre-
paration by long-lived isotopes of tellurium. The short half-value periods belong to Sb/17 (97% K and 3% 8+,
T112 = 2.8 hours) [4] and Sb116 (8+ , TV2 = 15 min, E8+ = 2.4 Mev) [5], [6.1* According to our measurements
the K-capture branching ratio for Sb116 is about 10%.
* The isomer of Sb116 with half-value period 60 minutes [7] has not been observed in our work.
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From this it follows that the tellurium activity with half-value period 2.5 hours belongs to a mixture of
the isotopes Te 116 and Te117. From the decrease with time of the radioactivity of the daughter products it was
found that the half-value periods of Te 116 and Te 117 are 2.5 hours and 1.7 hours, respectively.
It was impossible to determine the K-capture branching,ratios of the individual tellurium isotopes because
of the nearly equal half-value periods and the accumulation of the daughter products. It could be shown, however,
that the main type of decay of these isotopes is K-capture. When there are equal amounts of Te 116 and Tel" ,
7510 of the preparation, apart from that of the daughter products, is in acts of capture of an orbital electron.
LITERATURE CITED
[1] M. Ia. Kuznetsova and V. N. Meldiedov, Izv. AN SSSR, Ser. Fiz. 21, 1020 (1957).
[2] G. Seaborg, I. Perlman, and J. Hollander, Table of Isotopes (Russian Translation) (IL, Moscow, 1956).
[3] R. King, Rev. Mod. Phys. 26, 327 (1954).
[4] C. L. McGinnis, Phys. Rev. 97, 93 (1955).
[5] P. Srahelin and P. Preiswerk, Nuovo cimento 10, 1219 (1953).
[6] A. Aten, I. Manassen, and G. D. De Teyfer,, Physica 20, 665 (1954).
[7] P. Srahelin, D. Maeder, and M. Pochou, Z. Physik, 140, 498 (1955).
Received December 11, 1957
MEASUREMENT OF 8-ACTIVITY IN AN END COUNTER
N. E. Tsvetaeva and M. N. Brusentsova
The determination of 8 -activity of samples by measurement with an end counter requires the introduction
of a number of corrections which take account of the solid angle, the absorption of the 8-radiation in the counter
window and the air gap between the counter and the sample, back scattering, self- absorption in the source, etc.
Usually, a general correction is made for the absorption in the counter window and the air [1-3]. When
this method is used one adds to the thickness of the window an equivalent thickness for the air gap. The correc-
tion is introduced graphically, extrapolating the absorption curve of the 8 -radiation,or by multiplying the measured
quantities by the factor [1, 2]
twin + t air
T=2 d112
where twin is the thickness of the counter window, tair is the width of the air gap, d412= f (E 0) is the thickness
of the layer in which half of the radiation is absorbed (all quantities are given in mg/cm2).
The values given in the literature [1, 2, 4] for the thickness of the layer in which half the energy is ab-
sorbed as a function of the 8-radiation energy, dy = f(E0) differ considerably among themselves (Fig. 1).
2
The values of dy for the nuclides S 35, Ca', Co60, T1204, RaE, P32, and UX2 have been measured by
absorption of the 8 -ralation (Fig. 1, Table 1).
The measurements were carried out with a VFL-25 end counter having a mica window 1.1 mg/cm2 thick
with a distance of 3 cm between the sample and the counter window. An aluminum absorber was placed against
the counter window. The results were found to be in disagreement with the relation for di/2 = f (Eo) reported
7
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in a paper by Bochkarev et al., [1] and in the book by Gusev [4]. The values for the half-absorption layer are
in agreement only for small absorber thicknesses.
mg/cm2
75
50
25
1
/
A
/
I?
II /
I. .
3
/ ?
/412 4 0 RaE
y .
,e Sr
60
1,0 2,0 3,a
E0, Mev
Fig. 1. The function d11 = f (E0). 1) Data of
Gusev [4]; 2) data of Boclikarev et al., [1];
3) data of the present work.
1
z_-(1
2, '0
2,00
1,90
1,80
,70
1,60
1,50
t,4
1,30
1,20
1,70
1,00
1N6%
J
01
a
.
co
60
Pr r
C3
MO f
n
'
,
0
#,)'06
1,0 2.0 3,0
, Mev
Fig. 2. The correction factor for absorption of B-
radiation in air as a function of maximum energy
of the B- radiation
/
p= v
- 1 (E0).
'768
TABLE 1
Values of (11/2= (4).
d112, mg/cm2
Nuclide
Mev
present
.data of
data of
data
[I]
[4] *
S35 . . .
0,167
2,8
3
3
Ca43 . . .
0,254
3,9
5,5
5,48
T1204 . .
0,765
15,1
25
34,5
Se? . . .
0,54
8,7*)
15
20
RaE . . .
1,17
19
44
70
P32 . . .
1,7
34
77
121
* The layer for half absorption for 8 -radiation of
Sr" was determined from the accumulation of Y
TABLE 2
Comparative Data for the Determination of Absolute
8 - Activity
8-activity, decays/mmn
Nuclide
E0
Mev
41- -
.
counter
end -counter
present
data
data ob-
tai
ibtaiine(lual
Lue. od o '
calc.
Co" . . .
CS137 . . .
Sr" .-,. Y9?
0,306
0,52
{ 0'54 2,24
23 700
13 148
37 480
24 500
13000
35 300
36 200
16 600
40 200
The same approach cannot be used in determining
the corrections for the thickness of the counter window
and the air gap because the intensity of the 8-radiation,
all other conditions being equal, will be affected to a
great extent by the position of the absorber in the gap
between the counter and the sample.
We have determined the correction factors for the
? absorption of 8-radiation in air for Nb, S36, Cad, C060,
Zr, Sr", Cs137, T12", RaE,and Rhl?6 for an air gap
3 cm long (Fig. 2). These measurements were carried
out in a vacuum chamber, inside of which was placed
the sample being investigated and the VFL-25 counter
(in some cases an MST-17 counter was used). The
pressure .p in the desiccator was varied from 5 to 760
mm Hg.
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The corrections which were obtained (Figs. 1 and 2) were used to determine the absolute 8-activity of
Cs 137, Sr 93 ?4' Y??, and Con samples which had first been measured in a 4r -counter. The data are given in
Table 2; it follows from this table that the measure-
ments using the end counter agree with the measure-
ments with the 4r-counter to within ? Vb. In Table
2 are also shown results obtained by introducing
corrections for absorption in the counter window and
In the air by the usual method (from the total thick-
ness of the counter window and the air). At low 8-
energies these differ considerably from the results ob-
CO tained with the 4r-counter. For example, in Co?
(0.306 Mev) this discrepancy is more than 50%.
In Fig. 3 are shown the correction factors for
air as a function of the air-layer thickness between
1 and 10 cm for S35, Cad, Co60, and T1204. It is
3,0 apparent from these curves that for soft 8-radiation
(Ca45, and S 35) the correction factor increases sharply
2,0 as the air gap is increased between the limits indicated
above.
1:211.9
11,
8.0
20
1
4.0
2
3
t0
0 2 4 6 8 10 12 14
Distance from sample to counter, cm
Fig. 3. The correction factor for absorption of
of 8-radiation in air as a function of the air
gap. 1) For S s (0.167 Mev); 2) for Ca45
(0.254 Mev); 3) for Co6? (0.306 Mev); 4)
for T1204 (0.765 Mev).
The slope of the curves with respect to the abscissa
axis falls off as the energy is increased; in T1204 there
is a. relatively small increase in the correction factor
with increasing length of the air gap.
LITERATURE CITED
[1] V.'Bochkarev et al., Measurement of the
Activity of Data on Beta and Gamma Sources (Academy
of Sciences Press, USSR, 1953). *
(2./ V. I. Spitsyn et al., Operational Method With Radioactive Indicators (Academy of Sciences, Press,
USSR, 1955).?
[3] B. P. Burt, Nucleonics 5, 2, 28 (1949).
[4] N. G. Gusev, Handbook on Radioactive Radiation and Protection (Medgiz, 1956).4'
[5] G. Seaborg, I. Perlman, and G. Hollender, Table of Isotopes (IL, 1956). ??
Received December 20, 1957
? In Russian.
?? Russian translation.
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DOSIMETRY NOMOGRAM FOR DETERMINING WORKING TIME
IN A MIXED RADIATION FIELD
G. M. Obaturov
In practice, one frequently encounters working conditions in which personnel are exposed to y -radiation
in addition to slow neutrons, fast neutrons, and 8-particles; the atmosphere in the operating installation may
also be charged by active gases and aerosols. It is also possible for the elements of the installation and clothing
to become charged.
In these cases, in computing the permissible working time one must consider, in addition to the y -radiation,
the other types of radiation, the contamination of the air, clothing, and the installation itself.
The author has devised a dosimetry nomogram (see p. 771)for rapid calculation of the permissible working
time under conditions in which several harmful agents work simultaneously.
On scale 3 of the dosimetry nomogram are plotted values of the number N for the permissible radiation
levels, the contamination of the air by gases and aerosols, the contamination of the installation and clothing.
On scale 2 are plotted values of the function 1 /t; these are plotted in such a way that a permissible level
corresponds to a vertically determined value of 1/ t.
The numerical value of l/t is computed from the expression
1/t hours =0.125 N.
Along scale 1 is plotted the permissible working time for the conditions which are of interest here. The
values of N correspond to definite values of! at points of intersection of the vertical lines with both scales.
For example, with N = 20, the permissible working time is 24 min; with N =80 the permissible working time is
6 mm.
Along scale 4 are plotted the values of the y - fields in microcuries/sec corresponding to permissible level.
On scales 5-7 are plotted the values of fluxes for fast neutrons, slow neutrons and 0-particles corresponding
to the permissible level determined by a vertical line. The following permissible levels are taken [1]:
7-radiation
fast neutrons
slow neutrons
- particles
1.8 microcuries/sec
35 neut/cni2. sec
1100 neut/crn2. sec
75 particles/cm2. sec
The permissible level in gases and aerosols depends on the particular type. In the absence of any shielding
against the gases or aerosols,for argon the permissible level is 10-8 curies// , for 1131 this level is 5.10-12 curies//
etc. [1].
When a gas protective unit such as the PSh-1. PSh- 2, or clothing type LG-1 or LG- 2 is used,the permissible
level is 10-8 curies /1 (because of external irradiation by 8 -particles without taking account of the absorption in
the medium, the protective shield, and the jacket) for a- active gases or aerosols. For a- active gases and
aerosols (particularly pure a-radiators which do not radiate y-energy) the permissible level is unlimited when
the protection indicated above is used.
In determining the contamination of clothing and the body,the original numbers have been taken as the
limiting permissible levels used in the USSR.
In determining the working time with a contaminated piece of equipment, account must be taken of the
fact that the clothing itself will become contaminated to the same extent as the equipment; thus, the limiting
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.-.7
......c. .r.?
...=. .41 . =
I. U.,
= S_:.
....a-- Z ,....
0 : 2 _ -. V
_
_
7.- ., - - ',
,.-. _,-- . :
_..: - ,?=._ -, -
-.
-.7.-. ..-
- ?41. ,
.. -
0 '--- _ 0 _,,-'
--.. ? es _ -77
-a.' ; g -
-. 0 ??????
-
_
2: ?.:;,,..---
-_ .....,, _-
--=-1,,
a.4.- -
..
??
_.-....- , - , ,,... -- __
...-1 -,_ _
..
-- ,, ,?, ? ?, _
.. -__ ? _ .:>
_
--Z- CC to_ 0/to,..S , V F..1.1 _!--
to = to - to
S. 0 o.," _ -,-
........ '' - -,-..-
7..-- 1.0 ...., -
N
= Fl, 0 -
..-'...--
- ...
,.:, _ ,, _,- ... _
.. .,.... , z ?
..= .,,e?
en -
__,.a, _ ..,.. ___--.,
, ......,_,_
to
0* ...r = ,r ^to ,
-
..- -- .8 .1 - IF1
"b. ?
.
.,.,' - 0 0
.S
to
-
-
-C-
0 a-
-
_
?01
' ? In Russian.
03
??.to
to to.tO Ito
Dosimetry Nomogram
permissible level for contaminated equipment is equal to the
limiting permissible level for outer clothing.
The contamination of the equipment is verified by taking
smears. If the active meterial is deep in the substance and does
not contaminate the 'clothing, the contamination is taken as zero
and one need compute only the flux of 8-particles for y -radia-
tion from the equipment itself.
We now illustrate the use of this dosimetry nomogram.
Suppose that in a given installation the y -radiation is 20
microcuries/ sec, the 8 -particle flux is 100 particles/ cm2 -sec,
the fast-neutron flux is 100 neut/ cm2 ? sec, the contamination of
the equipment is twice the permissible level, the contamination
of the overalls is 0.5 of the permissible level.
It is required to find the permissible working time in this
installation.
Using the nomogram we determine the value of 1/ t for
each factor. The following values are obtained: 1.4, 0.17, 0.36,
0.25, and 0.06. The total is 2.24, which corresponds to a per-
missible working time of 27 minutes.
A person working in a mixed radiation field receives an
actual dose which exceeds the y -radiation dose.
The total, dose, expressed in ber-units is computed from
the formula taken from [1]:
D = D?
'tot
ty
where Dy is the dose received in the working time due to y -ra-
diation which is determined by the individual personnel dosim-
eter (a filM badge type or a KID-1): ty is the permissible time
computed taking account only of the y--radiation, ttot is the per-
missible time computed taking account of all forms of radiation
and contamination.
For example, in measuring the radiation and contamination
for the purpose of determining the permissible working time in a
mixed radiation field we find ty = 3 hours and ttot = 2 hours.
After the work a dosimeter of the KID-1 type showed 0.5
of the permissible dose.
Hence the true dose is found to be
3
D = 0.5 = 0.75 of the permissible dose
The dosimetry nomogram which has been described may be
used conveniently for carrying out many types of calculations un-
der different working conditions.
LITERATURE CITED
[1] N. G. Gusev, Handbook on Radioactive Radiation and
Protection (Medgiz, 1956).*
Received January 25, 1958.
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SCIENTIFIC AND TECHNICAL NEWS
ON THE PRESENT STATE OF THE PROBLEM OF ACCELERATING
ATOMIC PARTICLES
(From the Annual Session of the Academy of Sciences of the USSR)
At the Annual Session of the Academy of Sciences of the USSR, convened in March, 1958, Corresponding
Member V. I. Veksler of the Academy of Sciences delivered a speech dealing with the present state of the
problem of atomic-particle acceleration. He gave an account of the history of the development of accelerator
techniques, and of the difficulties standing in the way of further step-ups in the energy and intensity of beams
of charged particles.
The technique of strong beam focusing, proposed by the American scientists Courant, Snyder and Living-
ston* had opened the way for increasing the maximum energy of accelerated particles only by a factor of
several times. In order to obtain beams of high-energy particles with energies in the hundreds ,and thousands
of billions of electron-volts, new accelerating techniques are called for. One of these methods is based on the
use of colliding beams of high-energy particles [1]. The process of interaction, as for example, in the collision
of two 10-Bev protons moving head-on against each other, matches the effect produced by the bombardment of
an immobile proton by a proton of about 200 Bev energy. To enhance the probability of head-on collision
between particle beams, the instantaneous values of the current flowing in the accelerators must be raised by
500-1000 times.
We are familiar with the fact that A. A. Kolomenskii, V. A. Petukhov, and M. S. Rabinovich [2] in the
Soviet Union suggested, in 1953, magnetic systems using a time-invariant magnetic field, which would facilitate
considerably the achieving of increased beam intensity in high-energy particle accelerators. A similar suggestion
was voiced somewhat later in the U.S.A. as well (D. W. Kerst, Simon et al,).
V. I. Veksler drew attention to the fact that further research and development work on high-energy particle
accelerators using large currents is out of the question unless the collective interaction between particles and
studies on processes taking place in plasma are taken into account.
In 1956, the Soviet scientist la. B. Fainberg [31 pointed out the possibility of employing a plasma immersed
in a magnetic field in particle accelerators. In a linear accelerator coupled to a plasma-filled waveguide, it is
possible to combine conditions of phase and space stability which are usually incompatible for a beam of particles.
An intriguing method for making use of plasma in order to obtain high magnetic field strength (in hundreds
of kilo-oersteds) has been proposed by the Soviet scientist G. I. Budker [4], With the aid of this technique, the
dimensions and weight of accelerators were considerably reduced.
In the conclusion of his address, V. I. Veksler spent some time on the coherent method of accelerating
atomic particles [5]. This technique of particle acceleration involves the use of the interaction of small bunches
of charged particles with a stream of high-energy electrons, or the interaction of a bunch of particles at rest with
a relativistic bunch of particles of large mass. The interaction between charged, and even quasineutral, bunches
and electromagnetic waves may also be used. The magnitude of the accelerating field in the coherent method
* E. D. Courant, M. S. Livingston, and H. S. Snyder, Phys. Rev. 88, 1190 (1952). The Strong-Focusing
Synchrotron, a New High-Energy Accelerator."
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is proportional to the number of accelerated particles available. V. I. Veksler considers that, with the aid of
the coherent method, it will be possible to proceed to the development of accelerators operating at very high
current levels and accelerating to superhigh energies of the order of 1012 ev and higher.
LITERATURE CITED
[1] G. K. O'Neill, Phys. Rev. 102, 1418 (1956).
[2] A. A. Kolomenskii, V. A. Petukhov, and M. S. Rabinovich, Symposium: 'Some Problems in the
Theory of Cyclic Accelerators," (Izvestiia Akad. Nauk SSSR 1955), p. 7.?
[3] K. D. Sinel'nikov, Ia. B. Fainberg, and P. M. Zeidlits, CERN Symposium, Proceedings, 1, 84
(Geneva, 1956).
[4]
G. I. Budker, J. Atomic Energy (USSR)
1,
5,
9 (1956).**
[5]
V. I. Veksler, J. Atomic Energy (USSR)
2,
5,
427 (1957).**
N. F.
7-Bev AND 12.5-Bev SYNCHROCYCLOTRONS
A communication has already been published, in 1957 [1], on the 7-Bev synchrocyclotron project under-
way at the National Institute for Research in Nuclear Physics (Britain); some of the details pertaining to the plans
for this proton accelerator have been made public since that time [2].
The chamber measures 45 meters in diameter. The weight of the magnet poles is 6000 tons. The building
of reinforced concrete which houses the accelerator occupies an area 60 meters across (see Fig. 1). The concrete
roof of the structure, with a thickness of 1.35 meter, will be covered over by a layer of earth 3 meters deep, If
it is found necessary, the thickness of the earth roof shielding may be doubled. Biological shielding of the per-
sonnel will be provided by an earth fill-in and shielding blocks. The basic shielding wall, separating the
accelerator site from the measurements pavilion, will be made of concrete 8.4 meters thick, with removable
blocks, The measurements pavilion will be surrounded on all sides by earth embankments. Particle beams ex-
tracted from the chamber of the accelerator will be absorbed at the terminus of long tunnels hollowed out in the
walls of the measurements pavilion. Protective screening against radiation may be installed above the targets.
The area set aside for the housing of the remote control apparatus for the accelerator, for measurements gear
and preoperational equipment, will occupy 360 m2.
At the Argonne National Laboratory (U.S.A.), construction of a 12.5-8ev proton synchrocyclotron has been
proposed [2, 3]. The cost of the accelerator is estimated at 27 million dollars. Figure 2 gives a view of the
arrangement of the basic units of the accelerator.
The synchrocyclotron injector unit will be a 50-Mev linear accelerator. Protons will be introduced into
the chamber from the interior of a toroidal magnet. The radius of the orbit will be approximately 29 meters.
The duration of an acceleration cycle will be 1 sec. Pulses of particles will be repeated every 4 sec. It is pro-
posed that this accelerator should yield a greater number of particles than any existing or projected accelerator
of similar design.
? In Russian.
** Original Russian pagination. See C. B. Translation.
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Fig. 1. Diagram showing site of basic components of planned 7-Bev synchrocyclotron (Britain). 1) Injector,
2) accelerator room; 3) measurements cubicle; 4) hydrogen plant; 5) bubble chamber; 6) measure-
ments pavilion; 7) heat-exchanger plant; 8) motor-generators; 9) building for assembly and testing;
10) building for control of accelerator and for preliminary work; 11) administration and laboratory building.
$1111111111101111111111111111111111111111111111111111111111
1111111
illilinglimirinio1111111111111111111111111111111
Fig. 2. Diagram showing site of basic components of projected 12.5 Bev synchrocyclotron at Argonne National
Laboratory. 1) Building for meson measurements; 2) shielding embankment; 3) toroidal magnet; 4)
building for proton measurements; 5) injector; 6) building for housing electrical gear; 7) accelerator
control building.
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LITERATURE CITED
[1] Nucl. Engineering 2, 18, 401 (1957).
[2] Engineering 185, 4792,42 (1958).
[3] Engineering 184,4772, 255 (1958).
N. F.
A SINGLE-DEE CYCLOTRONS
In a conventional cyclotron with two dees, it is not always possible to perform experiments within the
accelerating chamber because of space limitations in the area between the dees with their large high-frequency
potential. These difficulties are completely eliminated in a cyclotron using a single dee. Instead of the
second, a "grounded" frame or dummy dee ["Gegendeel is installed. The chamber space made available in
this manner may be utilized for the placement of measuring probes, ion sources and deflecting systems, while
the structural shaping, adjustment and operation of these devices is facilitated to an appreciable degree. In the
single-dee cyclotron, the axis of the resonant circuit is directed perpendicular to the accelerating slot between
the dee and the grounded frame, with the result that the electric field existing in the slot proves to be symmetric
with respect to the center of the slot. As a result of the greater freedom in the choice of the diameters of the
stub and tank of the resonant circuit in the single-dee cyclotron, it is possible to achieve a greater stability in
the position of the dee in the chamber than is the case with a double-dee cyclotron. The high-frequency power
losses are about the same in either case. Consideration should be given, however, to the fact that a single-dee
cyclotron has one substantial drawback; the difference in potentials between the 'dee and frame must be twice
the potential difference in a double-dee cyclotron.
All the considerations cited were taken into account in the redesigning of the Heidelberg cyclotron. Since
September, 1956, this cyclotron has been operating with a single dee. The figure below shows a cutaway view
of the arrangement.
''.otiih1111111iin
?NLIN
11111111
Diagram of chamber and resonant circuit of cyclotron
at Heidelberg. 1) Dee; 2) grounded frame
("Gegendee"); 3) pole; 4) ion source; 5) vacuum-
pump connection; 6) high-frequency cable; 7)
vacuum meter; 8) dee-adjusting device; 9) resonant
circuit shorting plate.
the high-frequency current flows, are covered with
The peak energy given to the cyclotron
deuterons is 12.9 Mev. The strength of the magnetic
field is 16.9 kilo-oersteds. The diameter of the
magnet poles measures 101 cm, the pole gap 27.6 cm.
The chamber lids are made of soft magnet steel
(diameter 100 cm, thickness 6 cm, distance between
lids 15 cm). The weight of the magnet is 80 tons,
and the available power 54 kw. The magnetic field
has 0.01% stability.
The chamber, manufactured from nonmagnetic
chrome-nickel steel, has five removable aluminum
walls, each 2 cm thick. Deflecting instruments, ion
sources and two ports allowing access to measurement
probes may be installed on the three forward walls of
the chamber. Dee-voltage meters and piping for
cooling of the frame may be mounted on the lateral
walls. The surfaces of the chamber, along which
electrolytic copper.
* R. Bock, A, D-ohring, J. ranecke, 0. Knecht, L. 'Coster, H. Maier-Leibnitz, Ch. Schmelzer, and U. Schmidt-Rohr,
Zeitschrift far angewandte Physik 10, 2, 49 (1958) "E in Festfrequenz- Zyklotron mit einem Dee."
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The distance between the dee and the chamber coverings is 3.8 cm, while the internal height of the dee
at the center is equal to 6 cm, with a height of 4.2 cm at the periphery. The diameter of the tank circuit stub,
to which the dee is fastened, measures 21 cm, while the inner diameter of the tank is 112 cm. The position of
the dee inside the chamber is controlled with the aid of an adjustment device situated on the shorted end of
the resonant circuit. The gross weight of the chamber and resonant circuit is about 3 tons.
The quality factor Q of the resonant system of the cyclotron is closely dependent on the amplitude of the
high-frequency voltage and on the state of the vacuum. The rated Q =15- 103. Measurements performed with
the aid of a microwave laboratory oscillator (small voltage amplitudes) showed that, at a pressure of 10-5 mm Hg,
immediately following the shutting off of the cyclotron and after a protracted period of rest, Q = 3.103, while
in the range of pressures from 10-3 to 76 mm Hg, Q = 10.8 -103, At high voltage amplitudes (for measurements
in this case, a high-frequency cyclotron oscillator was used), and over the range of pressures from 10-5 to 10-6
mm Hg, Q = 10.8 ? 103. The lowering of Q at low amplitudes is associated with multiple high-frequency oscilla-
tions of the charges formed in response to the ionization of the residual gas. With increased pressure, the mobility
of the charges dropped off, and Q increased correspondingly. When the high-frequency field oscillated at large
amplitudes, the oscillatory process did not have time to build up, so that the charge was rapidly drawn off to the
walls.
The high-frequency oscillator is a seven-stage oscillator. A frequency of 12.8Mc is obtained after the
frequency of the driving oscillator is doubled three times, In order to avert the appearance of a glow discharge
in the resonant circuit tank at low high-frequency voltages, a steady voltage of 2 kv is applied to the dee and to
the stub. For this purpose, the shorting plate in the resonant circuit is made of two parts, separated by a vacuum
capacitor of 0.15 ji f total capacitance. The change in the grid bias of the high-frequency oscillator second
stage may pass rapidly through the danger voltage region of 5-15 kv. After an amplitude of 15 kv is attained,
the need for constant voltage is not so pressing. The peak dee voltage value obtained with this cyclotron reaches
100 kv. The dee and the frame are covered with a layer of chromium (25 ), which protects their surfaces against
oxidation and scratches suffered in disassembling the cyclotron, while at the same time reducing the number of
high-voltage breakdowns. For protection against protracted discharges, provision is made for a special automated
control system shutting off the high-frequency oscillator.
The strength of the magnetic field was measured to an accuracy of 0.01% by an instrument based on the
principle of the Hall effect.
The inner annular shims have a width of 8.5 cm and a maximum height of 1.1 cm. Collapse of the field
at an end radius of 42.5 cm is about 1.5%. The maximum deviation of the average bounding surface of the
magnetic field from the mean geometric plane at a radius of 37-39 cm comes to 0.8 cm. The deviation of the
surface at a terminal radius is equal to 0.2 cm. The azimuthal nonhomogeneity of the field is less than 0.1%.
An ion source with a capillary arc and graphite "adapters" is used in the cyclotron. The peak ion current
provided by the source is 30 ma, and 0.5 ma at the terminal radius. The energy spread of the beam, as measured
by the method of slowing down deuterons in aluminum foils and on the basis of a change in the coloration of LiF
crystals, comes to ? 1%.
The vacuum equipment of the cyclotron consists of an oil diffusion pump (Leybold OT 8000) with a
pumping speed of 8000 liters/sec, a booster steam oil pump and two mechanical pumps. The diffusion pump
is connected to the tank of the resonant circuit by an exhaust duct measuring 40 cm in diameter. A grid placed
across the end cross section of the duct (10 strips of copper foil) eliminates any distortion of the high-frequency
field in the circuit tank due to the pumping orifice. The volume to be pumped out is 3 m3. In 12 hours of
pumping after the first operational assembling of the unit, a vacuum of 8- 10-6 mm Hg was achieved. A one-
hour run-in of the chamber led to an improvement of the vacuum to 5. 106 mm Hg. The pressure rise with
the pump valve closed reaches 5 -1C8 mm Hg per sec.
A. B.
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A 1-Bev SYNCHROTRON IN ITALY
At the National Laboratory in Frascati (15 km north of Rome), a synchrotron is being built to yield electron
energies of 1 Bev [1. 2]. The maximum magnetic flux density at the orbit Bmax = 9260 gauss. The frequency of
the alternating current feeding the magnet is 20 cps. The amplitude of the variable component of the flux density
and the magnetization vary over a range from 4170 to 4630 gauss. The radius of the fundamental orbit R = 360 cm.
The number of rectilinear intervals N = 4. The length of these intervals L =120.6 cm. The period of revolution
of an electron toward the end of an acceleration cycle (v = c) T = 9.154.10-8 sec. The parameter of the collapse
of the magnetic field n = 0.61. The total injection energy Ei = 2.5 Mev. The field induction, at the orbit, is
Bi = 22.7 gauss on injection. Frequency ratio k = 4. Injection frequency iij = 42.78 Mc, and, at the end of an
acceleration cycle, vf = 43.70 Mc. The theoretical value of the modulation index for the frequency is Milo.
machine
shop
cond ensers
resonators
injector
controls console
pumps
experimental
roori),
JI-
0 2
8
111
Floor plan of 1-Bev synchrotron installed at the National Laboratory in
Frascati. 1) Machine shop; 2) condensers; 3) resonators; 4) pumps;
5) experimental room; 6) injector; 7) controls console.
The gap between the magnet poles is 8.6 cm, the width of-the poles 22.7 cm. The weight of iron in the
magnet is approximately 93 tons, and the weight of copper is approximately 8-10 tons. ARMCO-DI-MAX
silicon steel sheet (0.35 mm thick) was used. Capacitance of the bank of condensers is 3420 If f. An ac generator
delivers a power of 510 kva, while a dc generator supplies 315 kw. The sketch shows the ground plan of the syn-
chrotron laboratory and the location of the basic equipment.
LITERATURE CITED
[1]
Atomo e Industria
1,
1-2,
9 (1958).
[2]
Atomo e Industria
1,
3, 3
(1958).
778
N. F.
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MEASUREMENTS OF THEIZMNI, NEUTRON SPECTRUM
IN A SWEDISH D20 REACTOR Itl*
Measurements of the energy distribution of neutrons expelled from nuclear reactors show that no thermal
equilibrium is established between the neutrons and the atoms of the moderator in the reactor core lattice. The
effective neutron temperature exceeds the moderator temperature by 50-150? C.
In the paper reviewed in the present discussion, the energy distribution of the neutrons emergent from the
horizontal channel of the Swedish heavy water reactor Ftl were investigated. The arrangement of the experiment
is diagrammed in Fig. 1.
2 3 4
wy .1.7167.
__WO' A
Fig. 1. Experimental arrangement (with beryllium filter inserted).
1) Cast-iron collimators; 2) beryllium filter, 20 x 10 x 10 cm ;
3) cooling jacket filled with liquid nitrogen; 4) evacuated stainless-
steel container; 5) mechanical chopper; 6) BF3 counter measuring
30 mm across; 7) shielding.
Cast-iron collimators shaped a neutron beam with a cross-section area of 10 x 5 cm2. For the investigation
of the "cold' part of the spectrum, a beryllium filter, 20 cm thick, cooled by liquid nitrogen, was inserted into
the channel. Analysis of the neutrons was carried out by a velocity delay selector using a slow neutron chopper
with curved slits, a boron trifluoride- filled detector and a 100-channel time analyzer.
A flux of neutrons of less than 0.4 ev energy (cadmium cut-off level) at the output of the channel proved
to be equal to 3.4.108 neutrons/cm2- sec with the reactor operating at 600 kw power. The cadmium ratio was
equal to 65. When the beryllium filter was introduced into the channel, the neutron flux dropped off to 4.4.106
neutrons/cm2.sec.
Correction terms were introduced into the measurements of the neutron spectra for: 1) misreadings in
discrete channels of the selector (up to 30%); 2) the epicadmium neutron background (up to 30%); 3) the
dependence of the transmission function of the chopper on its speed of rotation (up to 13%); 4) self-screening
effect of the counter (up to 100%); 5) absorption and scattering of neutrons in the six-meter-long air gap between
the reactor and the counter (up to 50%); 6) absorption and scattering in the 25 mm thick aluminum traversed
by the beam. With the aid of the last correction, irregularities in the slope of the neutron energy distribution
curve, in the 4.05 to 4.65 A wavelength region (Bragg cut-off wavelengths in aluminum) were eliminated.
Figure 2 shows the distribution measured empirically. The slow-neutron spectrum is given the best fit by
the formula
dn= const lcm exp
(1)
where m =4.07 (instead of m =4 for a Maxwellian distribution), x 0 =1.67 A. The neutron temperature, arrived
at with the aid of the constant x 0, was equal to 341 ? 10? K at a moderator temperature of 298? K.
* K. E. Larsson, R. Stedman, and fi, Palevsky, J. Nucl. Energy 6, 3, 222 (1958).
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The energy distribution of the neutrons passed through the beryllium filter experiences a sharp discontinuity
at the cut-off x = 3.96 A. The distribution at X > 4 A is described by Formula (1) with the same in and X0.
6000
5000
88190 ( 1 2
67
A4 exp - dA
A
4) 3000
2000
1000
8 9 2 40 ?
u j1.5 exp
2
1,67
e
dA
2,0 3,0 4,0 5,0 6:0
Wavelength X , A
Fig. 2. Energy/distribution of neutrons of wavelength x 90%
6
940 x 75 X 0.635 mm
23%
77%
296? C
310? C
light water
2. 1013 neutrons/cm2? sec
5 ? 1013 neutrons/ ems ? sec
5. 105 sec
0.7 ? 10-5 Aeg-I
light water
12 ms
0.52 ms
38? C
70 atm
285? C
35.8 m/hr
50 kg
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Thermal stresses
Maximum/average ratio in heat generation:
axially 1.6
radially 1.3
Heat flux in core:
average 244 thousand kcal/m2. hr
maximum 542 thousand kcal/m% hr
critical 2170 thousand kcal/m2.hr
LITERATURE CITED
[1] Atomic Ind. Reporter; 130, 3 (1957).
[2] Nucleonics 16, 2, insert (1957).
[3] J. Atomic Energy (USSR) 3, 9, 266 (1957).*
[4] Nucleonics 15, 7, 56 (1957).
Iu. K.
FLUORIDE FUEL FOR HIGH-TEMPERATURE REACTORS
One of the promising trends in contemporary reactor design is based on the concept of utilizing uranium
in the form of compounds, thus opening the way for developing circulating-fuel reactors. A reactor of that type
may be exemplified by the homogeneous heavy-water reactor at the Oak Ridge National Laboratory, where the
possibilities of designing reactors to operate on circulating nuclear fuel have been under study for quite some
time. In this reactor, a slurry of uranyl sulfate in heavy water is employed. However, besides advantages such as the
excellent slowing-down power of heavy water and the good solubility of UO2SO4 in D20, the reactor also ex-
hibits a number of drawbacks: the fuel must be kept under high pressure (in order to obtain high efficiency);
an explosive mixture forms during the operating process (necessitating the provision of special recombination
chambers).
Another circulating-fuel reactor is the LMFR (liquid metal fuel reactor) at Brookhaven National Laboratory,
operating on U-Bi, a uranium-bismuth alloy. Although there are no particular disadvantages inherent in the
reactor type referred to above, it has some weak points of its own, due to the danger of the solution solidifying
at low temperatures and the low solubility of uranium in bismuth.
The last-mentioned disadvantage may be eliminated by employing a fused mixture of uranium tetra-
fluoride and thorium with fluorides of the alkali metals, zirconium and beryllium.
Table 1 presents the physical properties of some of the fused fluoride mixtures, Inspection of the table
reveals the fact that the specific heat, heat conductivity, viscosity and Prandtl number for the mixtures tabulated
and for water are of the same order. The somewhat higher viscosity of the fluorides is offset by their high specific
heat. Along with this, fluorine exhibits highly satisfactory nuclear characteristics. The capture cross section of
fluorine for thermal neutrons is of the same order as the cross section of beryllium. The mean logarithmic energy
loss with one collision is approximately ,0.10, which is somewhat lower than for graphite; a system in which
slowing down took place only in fluorine would occupy too high a volume, thus necessitating the use of additional
? Original Russian pagination. See C. B. Translation.
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moderators. Furthermore, fluorine has an excessively high slowing-down power which would prohibit the use of
fluorides in fast reactors.
TABLE 1
Physical Properties of Some Mixtures of Fluoride
Composition
(mole%)
Melting
point,
? C
Density at
700? C,
eel"3
Volume co-
efficient of
expansion,
deg-1.
Viscosity
at 700?C
cp
Thermal
conductivity
cal/sec ? cm
I ? deg
specific
heat,
caVg .deg
Prandtl
number
53,5NaF -40Zr F4 - 6,51)124 . .
540
3,27
3,36.10-4
5,7
0,005
0,24
2,74
71LiF-16130F2-12111F4-113F4
525
3,25
2,52.10-4
7,1
-
0,37
67L1F-30,513cF2-2,51.1F4 . .
. 464
2,10
1 .90.10-4
5,5
-
0,57
-
Water (20? C)
-
- ?
-
1,00
0,00143
1
7
The slowing-down power of the fused fuel may be improved by addition of beryllium fluoride (BeF2),
although the higher viscosity of such a mixture would set limitations on BeF2 content to 30 mole percent.
Table 2 cites the slowing-down power and resonance escape probability for several possible mixtures of
fluorides. It is clear from the table that the resonance escape probability differs substantially from unity even
for an ideal fluoride mixture such as LiF-BeF2, and drops off sharply with increase in the amount of Li6 present.
With a Li6 content of higher than 0.1% in the LiF, a homogeneous reactor working on such a mixture will be
totally unable to go critical (just as in the case of a homogeneous reactor with a mixture of fluorides of the
alkali metals) [3].
TABLE 2
Nuclear Characteristics of Fluorides and Conventional Moderators
Composition (mole %)
Number of Li6 atoms
per one Li7 atom
Resonance escape
energies
up to 0.075 ev
Slowing-down power,
cm -1
D20
-
0,9997
0,18
Graphite
-
0,995
0,07
0
0,95
69 LiF-31 BeF2
0,0001
0,89
1
0,038
0,001
0,46
50 NaF -50 ZrF4
_
0,58
0,021
0
0,14
46,5 LiF-11,5 NO -42 KF
0,0001
0,13
1
0,018
0,001
0,059
The use of fluorides results in some specific difficulties. Among these are the problem of corrosion, and
the need to maintain a rather high temperature for the mixture, whose melting point is in the neighborhood
of 500? C. In addition, reactors based on the principle of employing fluorides, when compared, say, to water-
cooled reactors, require a higher fuel concentration to reach criticality, all of which leads tb relatively low
levels of power per kilogram of fuel. This disadvantage is offset, true enough, by the high plant efficiency
(as much as 35%) as a result of the high temperature of the circulating fuel [4].
One such reactor operating on fluoride fuel, the ARE (aircraft research reactor), is looked upon as one
of the possible prototypes for an aircraft prime mover. It was first described in several reports delivered at a
meeting of the American Nuclear Society in June, 1957. This reactor, installed at Oak Ridge National Laboratory,
was brought up to criticality on November 3, 1954. The fuel used consisted of a mixture of NaF, ZrF4, and
UF4, which was pumped in by centrifugal pump action through nickel alloy coils threading the reactor core.
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The fuel passed from the reactor to a heat exchanger, where it gave up its heat to an intermediate heat-transfer
agent, helium, which transferred the heat, in turn, to water (Fig. 1). Beryllium oxide functioned as both moderator
and reflector. The heat generated in the reflector was removed by circulating sodium and added to the water
through helium acting as an intermediate heat-transfer agent.
ID
p-/
5
8
7
10
Fig. 1. Schematic diagram of heat flow from reactor. 1) Central control rod; 2) core;
3) reflector; 4) fused sodium as reflector coolant; 5) fused fuel; 6) pump; 7) helium;
8) helium blower; 9) heat exchangers; 10) water.
Reactor control was carried out using a stainless steel rod passing through the center of the core, and also
using shim rods and safety rods of boron carbide.
The reactor (see Fig. 2) is a cylinder 85 cm across and 91 cm high; the width of the beryllium reflector
is 19 cm. On its outer surface, the core has 48 electric heating units delivering a total power of about 45 kw.
The flow speed of the fuel in the core is 1 meter/ sec (Reynolds number is 10,000). At rated power, the tem-
perature of the fuel at the entrance to the core was 650? C, while it reached 815? C at the core exit [5].
At first, a mixture of NaF and ZrF4 was circulated through the reactorpnall portions of 2NaF.UF4, 93.4%
U 235 enriched, were subsequently added. The reactor went critical at the following composition in the mixture
(in mole percent): NaF , 52.8; ZrF4, 41.0; UF4 , 5.7, corresponding to a content of 0.38 g U235 per cubic
centimeter of fuel. The critical mass was equal to 14.9 kg U 235, the total quantity of U 235 in the core and in
the out-pile loop amounted to about 66 kg [6].
The reactor was in operation 221 hours in all, including 74 hours of operation at full power. Although
the reactor design power is 1.5 Mw, it operated successfully even at a level of 2.5 Mw. After developing 96
Mw-hr the reactor was shut down and disassembled.
As was to be expected, the reactor possessed an over-all negative temperature coefficient. In response
to rapid changes in fuel temperature, the temperature coefficient due to the change in uranium concentration
-.4 A kik
?
reached 1.75-10 Slow changes in temperature brought about a positive temperature coefficient for
? C
A k k
the moderator, while the over-all temperature coefficient was 1.1 ? 10-4
?
c ?
It is interesting to take note of the fact that it proved possible to use absorber rods only to establish a
mean temperature in the reactor. Control is carried out for the most part with the aid of a change in the flow
rate of the helium coolant in the heat exchanger, as a result of which a change is effected in the temperature
of the fuel and, in turn, in the concentration of the uranium nuclei at the inlet to the reactor. This leads to a
change in the reactivity of the system. Thus, when the rate of flow of the helium is increased, the fuel tem-
perature at the reactor inlet is diminished, while it is increased at the outlet end (the mean temperature in the
reactor remains unaltered), with a consequent rise in reactor power. Figure 3 shows the results of one of the
experiments illustrating these self-regulating effects [3].
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2
4
Za7/ff OVZJIV/A
V /ffa'AI
a.
/ drAll
4,
'MO
III
AG=
\ \
AMON
-"if
Illoisommwmism.
i^ En Nom tom wz,/
\ _12
111
gra roxi
[
I. 111
11
I 11
I i
WSW :VW;
(40
AFAINEXM
wfteurroan
a
tr,
Fig. 2. Vertical cross section through the reactor.
1) Regulating rod assembly and safety rod assembly; 2) thermo-
couple; 3) core; 4) tubes for the reflector coolant; 5) fuel tubes;
6) support assembly; 7) helium manifold; 8) fuel outlet mani-
fold; 9) thermal shield assembly; 10) beryllium oxide moderator
and reflector, 11) heater units; 12) fuel inlet manifold.
As the experiment in operating the ARE reactor has demonstrated, Xe135 formation plays a very limited
role in poisoning. In the first place, the fuel is in the core only 1/4 of the time of a cycle, which is equivalent,
roughtly speaking, to reduction to 1/4 of the mean reactdr flux; in the second place, the majority of the neutrons
present have energies exceeding the energies of the largest resonance band of Xe; thirdly, in the process of
circulating the fused fuel, Xe135 as well as other gaseous fission products are volatilized from the fuel. This
791
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last fact made necessary complete hermetization of the fuel system. This problem was solved satisfactorily for
relatively short periods of reactor operation. However, small-scale escape of gaseous products from the surface
of the circulating fuel was still taking place, and this sometimes made operation troublesome [3].
tll **ail
o *Sieffitgit
str4
ca.
E ,T9
`.1).
12 II
10
9 8
7 65 4
1
Mat 4?4
? ,r: . :7
t-
Men
I:: ??'?.-
itit
4.
ti
?I 116
,0 va.4 cz, .0 ? .0 0, 14
Cd C:3 CS CS 0 iFS e.3 11,1 0.1
0 0 0 C:5 0 0 .0 NNN NNN
Time of day
`.1
Fig. 3. Temperature of reactor fuel. 1) Inlet fuel temperature; 2) outlet
fuel temperature; 3) reactor critical, power 200 kw; 4) slow increase in
rpm of fuel-system helium blower unit; 5) liquid-sodium-system helium
blower turned on; 6) power 2.5 Mw; 7) fuel-system helium blower rpm.
reduced to zero; 8) shim rods inserted; 9) fuel-system helium blower
turned up to full rpm; 10) regulating rod shifted; 11) fuel-system helium
blower turned off; 12) regulating rod inserted (reactor subcritical).
The practical value of the results obtained are not limited to their possible application in atomic-powered
aircraft construction. As calculations have shown, the cost of electric power delivered by a 240 Mw atomic-fuel
electric power plant with a molten fluoride-fueled reactor does not exceed the cost of electric power produced
in conventional electric power plants [4].
LITERATURE CITED
[1]
Nucl. Engineering 2, 16, 298 (1957).
[2]
Engineering, 184, 4783, 604 (1957).
[3]
N. K. Ergen et al.? Nucl. Sci. Engineering 2, 6,
826
(1957).
[4]
R. C. Briant and A. M. Weinberg, ibid., p. 797.
[5]
E. S. Bettis et al., ibid., p. 804.
[6]
E. S. Bettis et al., ibid., p. 841.
V. A.
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EXTRACTION OF URANIUM FROM SPENT NUCLEAR FUEL BY
DISSOLVING IN FUSED SALT AND FLUORINATION*
A new process for recovering uranium from irradiated uranium-zirconium fuel elements consists of
the following steps. The elements are subjected to hydrofluorination in a melt of NaF? ZrF4 or NaF? LiF
salts (6500 C). The uranium tetrafluoride forming as a result is fluorinated by plain fluorine to UF6 (600? C),
which is driven off as a gas from the fused salt,
along with volatile fluorides of impurity elements
to3
102
10-4
===,.... ?......-
of N2 flow
a
--
irate
o too ml/min
50 ml/min
? 20 ml/min
No
I?
---
-
MIMI
log P?,,?= 10,88- 5,09 x 10 r
+ 3 NaF ? UF6- 3 NaF
.
--"=="M
21=
imm omminommilimi
huF6
111111=11111E1111111MMIN=Wil
X
.
IIMIV71011=1111=1?111=1111
1.11111111
..111.0kjimaln.i=
MINE10.191..M.11111.1
?
allIMIIIIIMIN
=MI
iiiiiMMEM
Min&V
IIIIIM
.
========
.....==.....,...i.....
----u
16 1,9 2,2
lex VT (?K
Equilibrium partial pressure of UF6 above a
UF6- 3 NaF complex, plotted against temperature.
(Measurements by the transpiration method).
5
28
and excess of fluorine.
As a result of the insufficient fluorinating
potential of HF, volatilization of the impurity
elements is observed only to a slight extent in
the hydrofluorination or dissolving of uranium
tetrafluoride.
At the fluorination stage, excellent separa-
tion of the uranium from nonvolatile fluorides of
Cs, Sr, the rare earths and, to a smaller extent,
Zr, takes place. Uranium separation from fluorides
of Nb and Ru is poor , and is not achieved at all
for I, Te, and Mo.
For separation from volatile fission product,
UF6 is adsorbed on a column of granulated NaF at
100? C. The equilibrium curve for puF6 = f(T)
is shown in the accompanying graph. Desorption
of the UF6 is carried out with a flow of F2 passed
through the column at 400? C.
As the gas is filtered and scrubbed, activity
is distributed in three parts between U. Ru, and
Nb. The bulk of the Ru passes through the first
NaF column and is cold-trapped, while the UF6
and Nb are collected at 100? C. In the UF6 de-
sorption step, all of the Nb is in essence retained
in the first column. The second column serves to eliminate the activity picked up by the flow of UF6 in the
first column
TABLE
Decontamination of Irradiated Uranium in Fluorination and Adsorption on NaF Bed (Cooling time:
120 days)
Process
Decontamination factor
by 8-
radiation
by y -
radiation
Ru
Nb
Zr.rare
Cs, Sr,
earths
I, Te, Mo
Fluorination
Adsorption on NaF bed
Total
'
102
>104
>106
102
>104
>106
10
103
104
10
104
103
103-104
>103
>102
>104
103
>102
1
unknown
unknown
Recycling through the adsorption-desorption step brings about an over all decontamination factor greater
than 106 for the irradiated batches of uranium (see table).
V. P.
* G. J. Gathers, Nucl. Sci. and Engineering 2, 6, 768 (1957). R. P. Milford, Industr. and Engineering Chem.
50, 2, 187 (1958).
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ION EXCHANGE BEHAVIOR AND DISSOCIATION CONSTANTS OF
EDTA COMPLEXES OF AMERICIUM,CURIUM, AND CALIFORNIUM[1.1
A Dowex 50-X12 ion exchange resin in ammonia form was used for the study of the ion exchange equili-
bria of trivalent americium, curium, and californium. Ethylenediaminetetraacetic acid (EDTA) at 10-3 M
concentration was employed as the complexing agent. Constancy of the ionic strength of the solution was main-
tained by 0.1 M NH4C104. The experiments were carried out under static conditions at a temperature of 25 ?
? 0.02? C over a pH range extending from 2.0 to 3.3.
The experiments established the fact that complexes of the MeY-I type form in the pH range considered,
for trivalent actinide elements. In accordance with the equilibrium MeY-1 Me" + Y-4, the dissociation
constant Kc of this complex is written in the form
[meal y-aj K
IMeY ?
The distribution coefficient Kd for the actinide ion between exchanger and solution may be expressed in
the following form:
1
Kd=
ru4Arit
1+ l'?
OKc
where K is the distribution coefficient for me-F3 in the absence of the complex-forming agent, [H4Ylt is the
total concentration ot EDTA in moles! liter, 0 is the function of the pH and of the four dissociation Constants
of EDTA:
EH+) [H-]2 111]3 (1114
6=1
K4 K41(3 4K3A2+ 4K3K2K1
The following separation factors were obtained:
v Am
?
= Kd" =2,04?0,05,
KdCm
The dissociation constants for EDTA, obtained in [2J, were chosen for computing Kc; Kc then proved to
be equal to the following values:
californium
curium
americium
. . 10-19,09?0,2t
10-18,45?0,1,
10-18,1610,1.
Preliminary experiments performed on the ion exchanger under dynamic conditions demonstrated the fact
that EDTA may be used for the separation of the actinide elements.
LITERATURE CITED
[1] J. Fuger, J. Inorg. and Nucl. Chem. 5, 4, 332 (1958).
[2] M. J. Cabell, Analyst 77, 859 (1952).
794
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USE OF RADIOACTIVE ISOTOPES IN METALLURGICAL INVESTIGATIONS
Radioactive isotopes are receiving more and more attention in the elaboration of the technology and in
the study of ferrous and nonferrous metallurgy at the Metallurgy Institute of the Ural branch of the Academy
of Sciences of the USSR.
One of the most widely used isotopes is S 35. Research workers' teams from the Steelworking Processes
Laboratory of the Ural branch of the USSR Academy of Sciences, from the Ural Institute of Ferrous Metals and
the Central Laboratory of the Verkh-Iset metallurgical plant collaborated in studying the desulfurizing of
transformer-grade steel in a 14-ton electric furnace. For this purpose, a mechanical mixture of S 35 and iron
in proportions of 150 millicurie to 1 ton of the melt was introduced into the molten metal. Determining the
radioactivity of metal and slag samples taken every 5 min, the desulfurizing of the metal in the furnace and
in the ladle was studied. Several of the melts were produced in the manner of the routine shop technology,
with addition of S 35 to the metal immediately after the latter had melted down. In addition, in order to shed
some light on the desulfurization process, melts were produced at a lowered rate of metal output and with
agitation of the vat during the reduction period of the melting process. 8-12 samplings of metal and slag
were taken of each experimental melt. The peak activity of the metal (background deducted), was approxi-
mately 7.5 times less than the peak activity of a slag sample taken from the ladle. The maximum activity of
the metal corresponded to samples taken 5-10 min after S35 was introduced, while the minimum activity
corresponded to casting samples.
It was found that mixing of the metal with slag as the secondary slag was laid on, and alloying with
ferrosilicon,contributed to a more intense desulfurizing, and that slowing down of the rate of output of the metal
brought about essentially no change in the distribution of sulfur between metal and slag.
In order to give an explanation of the isotope exchange between metal and slag, addition of S 35 was made
to the slag as the metal was first being soaked in the ladle. Activity measurements of the metal and slag
samplings pointed up the fact that, after soaking the transformer metal in the ladle for 20 min or more, the
amount of S 35 transition from slag to metal was negligible, i.e., the rate of isotope exchange was slow under
those conditions.
S 35 was also used for studies of the mechanism of interaction between a number of sulfides with sulfates
and sulfur dioxide [1]. It turned out that, in the interaction of CaS with SO2, sulfide sulfur is completely
isolated, and sulfur and oxygen from sulfur dioxide enter into the sulfate then forming. In an analogous in-
teraction between cobalt sulfide and sulfur dioxide , an intermediate reaction takes place with formation of
metallic cobalt. For reactions involving interaction between sulfides and sulfates, the use of tagged sulfur made
it possible to work out more refined stoichiometric ratios, a problem which was difficult to tackle by conventional
techniques.
The mechanism involved in the desulfurizing of pig iron [2] was investigated using Fe59 isotope. In-
dustrially pure iron, saturated with carbon, was placed in two compartments of a graphite crucible, above which
was situated a common layer of molten slag containing no iron. Fe59 and sulfide of nonradioactive iron were
added to one of the components. After soaking for an hour at 1600 C, a determination of sulfur content was
carried out in the metal taken from the second compartment, and its radioactivity was assayed. The findings
so obtained showed that the sulfur passed over into the control alloy in rather high quantities, 1-2 orders of
magnitude higher than the iron. It was thus demonstrated that the iron passed over into the slag not in unison
with sulfur, but in the form of iron sulfide, or via some other process.
The further development of such techniques, adapted to the study of ores and concentrates of nonferrous
metals [3], employing Zn 65 and Se 75. made it possible to drastically reduce the amount of required experiments,.
to lessen the tediousness and to automate the performing of the experiments. Recourse was had predominantly to
zinc sulfate, precipitated by ammonium sulfide from a solution of a mixture of Zn65 and ordinary zinc in acid
medium. Se 75 was introduced into a copper concentrate (by the method of isotope exchange) and into synthetic
selenides, Se 75 also replaced sulfur in minerals of the chalcosine and chalcopyrite types. With the aid of Zn,
studies were carried out on the relative rates and completeness of vaporization of the metal as the sulfide was
heated in various gaseous media. It was found that sublimation of zinc sulfide took place, starting at 850 C.
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Oxidation of the sulfide vapors stepped up the rate of volatilization of zinc sulfide, while oxidation of the solid
surface slowed it down. The rate of sublimation also increased in response to reduction of the vapors by wood
charcoal, iron, or copper. Despite the low value of the vapor pressure of the sulfide, sublimation reached an
appreciable level in the course of the metallurgical processes studied.
Using Se 75 made it possible to establish the fact that volatilization of selenium in metallurgical operations
is favored by oxidative conditions and gets under way at low temperatures. When copper selenide oxidizes in air,
heated to 600? C for twenty minutes, for instance, 94% of the selenium present volatilizes out of the compound.
A team working at the Metals Casting Laboratory of the Ural branch of the Academy of Sciences of the
USSR used Co6? to determine the rate of mixing of charge materials and the smelting level. A cupola measuring
600 mm in diameter was irradiated with gamma radiation from a Co6? source (the source was shifted in the
vertical plane). The regularities uncovered enabled casting technologists to improve quality control in cupola
melting of pig iron.
Cos? was also employed for studies of metal distribution between mattes and slags in the nickel industry.
LITERATURE CITED
[1] N. P. Diev,* V. V. Paduchev, and V. V. Toporova, Sbornik trudov Instituta metallurgii ural'skoi
filial{ Akad. Nauk SSSR 2 (1958).
[21 I. L. Korkiia, 0, A. Esin, and V. V. Mikhailov, Doklady Akad, Nauk SSSR 1010 6 (1955).
[3] I. A. Vetrenko, N. P. Diev*, and A. I, Olesova, Sbornik trud. Inst. metallurg., ural'skoi filiali Akad.
Nauk SSSR 2 (1958).
N.A. Vatolin and E. A. Vetrenko
DEVELOPMENT OF URANIUM MINING IN CANADA DURING 1957
Data have been published in a number of Canadian periodicals referring to appreciable growth of uranium
mining activities in Canada during the year 1957 [1, 2].
These data are furnished in Table 1.
TABLE 1
Canada Uranium Yield During 1956 and 1957
Mining area
1956
1957
To in-
crease over
U303,yie1d
% of
U308 yield,
% of annual
tons
.
yield
nnual y
tons
yield
956
1'
Ontario (Blindaiver, Bancroft) .
408,0
- 20
3424,1
59
839
. .. . . .
Saskatchewan (Gunnar, Ice Bay, etc.), . .
1251,2
60
1987,5
34
\159
Northwest Territories (Great Bear Lake,
Marion)-
393,3
20
382,5
7
97
2052,5
100
5794,1
100
280
* Deceased.
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The general and notable increase in uranium mining activity in Canada was accompanied by a rather
extensive shake-up of the uranium mining industry, with the center of uranium ore mining being shifted from
the Athabaska Lake region in Saskatchewan to the neighborhood of Blind River, Ontario. Until 1958, the prin-
cipal uranium producer in Canada was the Eldorado mine on the shores of Great Bear Lake (Northwest Territories).
This general shift in the uranium mining industry is easily visible from the figures in Table 1,giving the
change in the specific weight of particular regions in the over-all uranium yield and tempo of development.
The abrupt jump upward in uranium mining in the Blind River area is due to the launching of six new
enterprises during 1957, these six being listed in Table 2.
TABLE 2
Enterprises Entering the Uranium Mining Field During 1957
Mines
Output, thousands
tons per day ,
Algom Uranium Mines (Nordic mine)
3
Consolidated Denison Mines
6
Stanley Uranium Mining Corp.
3
Norsspan Uranium Mines
(Nordic mine)
4
Norsspan Uranium Mines
(Pynel mine)
3
Can-Met Explorations
3
Thus, the 22,000 ton increase in the amount of ore processed daily was contributed solely by enterprises
new on the scene. There was registered, in addition, an increase in productivity over that achieved by enter-
prises engaged in mining and processing ore in previous years.
In April 1957, in the neighborhood of Bancroft, a uranium ore processing plant was put into operation at
the Faraday mine, with an output of 1200 tons of ore daily.
?
An increase in uranium mining was also recorded (albeit less than in Ontario) in the Athabaska Lake region,
largely as a result of the starting up of a new plant at the Lorado site, and also due to an increase in plant pro-
ductivity at the Gunnar and Ice Bay sites.
There was a modest drop in uranium mining during 1957 for the Northwest Territories mines taken as a
whole, in spite of the initiation of the new Rayrock Mines Ltd., with an output of 150 tons daily, working at
Lake Marion. This is evidently to be explained by the unfavorable results obtained at the Eldorado and Great
Bear Lake mining sites.
Correlation of the data on uranium mining operations in Canada with the data brought out by Johnson [3]
on mining in other countries shows that Canada has taken second place among the capitalist countries of the
world, being outdistanced only by the United States.
LITERATURE CITED
[1] Canad. Mining and Metallurg. Bull. 549, 2 (1958).
[2J Canad. Mining Journal 79, 2, 90 (1958).
[3] J. C. Johnson. Mines Mag. 11, 23 (1957).
M. K.
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BRIEF COMMUNICATIONS
USSR. Accredited representatives of the International Atomic Energy Agency visited the Soviet Union
during April, 1958, these being: general director of the Agency,S. Cole, assistant to the general director, P.
Yolles ,and chairman of the council of directors, P. Winkler.
Before his departure from Moscow, Cole held a press conference. In their statements, Cole, Winkler,
Yolles, as well as the head of the chief administration board on uses of atomic energy, attached to the Council
of Ministers of the USSR, Professor V. S. Emerianov, told of the problems and practical work of the agency.
At the conclusion of the interview, Cole answered reporters' questions. In answer, to questions directed at
him by the representative of the journal "Atomnaia Energiia," Cole stated the agency would begin, in the
immediate future, publication of its own press organ, and promised to send information on the work of the agency
for publication in our journal.
Australia. The first stage of tests (low-power tests) on the first Australian HIFAR high neutron flux re-
search reactor has been completed. The reactor was built near Sydney, in Lucas Heights.
Austria. Setting up of a research and educational atomic energy center has been proposed for a site 16 km
east of Vienna on the grounds of an old aerodrome near Hetzendorf. A 5 Mw tank-type reactor will be in-
stalled at the center.
England. At the scientific research atomic center in Harwell, a design has been worked out for a linear
electron accelerator operating under a pulsed regime (pulse repetition rate will be 400 cps), making possible a
sequential bombardment of two targets by the electron beam produced (Nucl. Instr. 2, 3, 282, 1958). The
beam will normally be deflected by an electromagnet to strike the first target, but the electromagnet will be
disconnected prior to each eighth pulse, and the beam will then be directed onto the second target. The
switching operation is carried out in the interval between pulses. Dimensions of the magnet pole pieces are:
length 6 cm, width 1.5 cm. Air gap between poles is 2 cm. The magnetic field strength, at an electron energy
of 13.5 Mev, amounts to 1 kilo-oersted (radius of curvature of electron path is 45 cm). Current build-up time
in the magnet windings is 1.25 millisec.
England. At Harwell, a design has been worked out for an atomic light bulb operating entirely from the
energy of radioactive substances. The bulb has a plastic envelope, and is inner-lined with phosphors. The
phosphors glow in response to beta particles emitted by Kr 85 which fills the bulb. The useful lifetime of the
bulb should extend to about 10 years.
England. An atomic clock operating at a rate of error of 3 sec in 300 years has been constructed at the
National Physics Laboratory in Teddington (Middlesex).
Afghanistan. Rich uranium deposits have been discovered in a mountainous area in Badakshan province,
in northeastern Afghanistan.
Italy. Work begins in the summer of 1958 on construction of an atomic research center at San Pietro a
Grado, near Pisa. The center, is being built by the University of Pisa, the Naval Academy at Leghorn and by
other scientific organizations. A tank-type materials-testing reactor delivering 12-1b Mw power will be
installed at the center.
U.S.A. At Yale University, a linear accelerator for heavy ions of elements up to neon became operative.
The energy of accelerated nitrogen ions reached 140 Mev. The length of the accelerator is 36 meters. The
power consumed at 70 Mc frequency is about 3 Mw. A similar accelerator is in operation at the Radiation
Laboratory of the University of California at Berkeley.
U.S.A. Construction work was completed during 1957 on 16 nuclear chain reactors, including 7 power
reactors and 9 research and experimental reactors. Construction has begun and is in progress on 59 reactors,
of which 35 are power reactors and 24 are research and experimental reactors. Construction of 7 uranium ore
reprocessing plants is underway, fuel elements production has been planned by thirteen companies, three
companies have completed construction Jobs on zirconium processing plants, and two companies have built
beryllium processing plants.
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U.S.A. At Cambridge, Massachusetts, construction work is in progress on a strong-focusing 6 Bev electron
synchrotron for the Massachusetts Institute of Technology and for Harvard University.
U.S.A. The leakproof structure of the cladding on one of the fuel elements ruptured in the
experimental boiling-water reactor BORAX-4 at the-National Reactor Testing Station in Idaho. Pellets formed
from a mixture of uranium and thorium oxide in tubular aluminum sandwiches are used in the reactor. The
reason for the failure was apparently a faulty welding job. The accident made it possible to observe the
functioning of the reactor with a certain proportion of the fission products still in the loop. The specific power
output of the reactor during the experiment was raised to approximately 50 kw/g. The activity of the loop
proved to be moderate.
U.S.A. At the Oak Ridge National Laboratory, a homogeneous experimental power-only reactor HRE-2
was started up. Thermal power of the reactor amounts to 5,000 kw. No electric power will be generated during
the initial operating period of the reactor.
U.S.A. EBWR, the boiling-water reactor at the Argonne Laboratory, designed for a thermal power of
20 Mw and already operating at a power output of up to 50 Mw, was adjusted to 61.7 Mw power.
U.S.A. At Cornell University, a design has been worked out for a training reactor with two separate
cores operating alternately. The first core (10 kw) is intended for use as a neutron source, while the second
(10 w) is slated for research in reactor physics.
U.S.A. AEC has allotted $ 191,000 to Rensselaer Polytechnic Institute for continuation of work on a pro-
ject studying the possibilities of using uranium oxide-containing fiberglass as a nuclear fuel. It is anticipated
that this material will show promise for use in high-temperature reactors.'
U.S.A. The seventh conference on hot laboratories and hot laboratory equipment will be convened at
Cleveland, Ohio, in Apri1,1959. Reports will be given at the conference on questions associated with the opera-
tion of hot laboratories, in particular instrumentation for work with radioactive materials, including questions
involving the design, production, use, maintenance, decontamination, redesigning, shielding design and cost of
laboratory devices, etc. Abstracts of reports to be proposed for the conference should be directed, prior to
September 15, 1958, to the following address: Brookhaven National Laboratory, Upton, New York.
U.S.A. The National Academy of Sciences, the National Research Council and the Society for Radiation
Studies are conducting the preparations for the International Congress on Radiation Studies to be held in Burlington,
Vermont,from August 10-16, 1958.
U.S.A. At the Livermore Laboratory, the AEC has worked out a new radiation-shielding material, in the
form of a slurry of superfine lead particles in paraffin. Use of this material to replace lead and concrete in
reactor shielding applications may permit reductions in shielding weight and thickness.
U.S.A. A lead camera has been designed to facilitate discovery of low-activity sources in the presence
of a highly radioactive background. This camera may also facilitate obtaining of conventional photographs of
radioactive objects which would require exposure of the film in ordinary type cameras. Two types of film are
employed in the camera: film of the conventional type and radiation-registering x-ray film. After both films
have been developed by superimposing one on the other, the position of the source of radioactivity can be
accurately pinpointed. A uranium lens with an aperture diameter of 0.0135 inch is used in the camera. The
camera weighs 13 kg.
U.S.A. A cobalt gamma ray facility with a source of up to 100,000 curies has been developed. The
unit will be placed below ground. The source will be kept under water. The exposure cell is 3.6 x 3.6 meters
in size. Observation of the process by remote viewing is proposed.
U.S.A-. RCA has developed a photomultiplier capable of discovering and recording events lasting less than
1 x 10-10 sec. The new device exhibits a resolving power of approximately 10-12 sec.
U.S.A. General Electric Company has designed an "electronic transducer" for the direct conversion of
thermal, i.e., heat energy into electrical energy. The device consists of two metallic electrodes, separated by
a gas at very low pressure, one of the electrodes being maintained at a relatively low temperature, while the
other is kept at a temperature in the neighborhood of 13700. The efficiency of the experimental electronic
transducers amounts to approximately 8% for the present.
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U.S.A. According to data released by AEC, the amount of radioactive strontium fallout increased by
50 10 during 1957. By early 1957, the over-all level of soil contamination by Sr" had reached 11.2 millicurie/
/km2 in the New York City area. By December, 1957, the total quantity of Sr" fallout in that area amounted
to 17 millicurie/km2. In a communication to the New York Times, published by that paper on April 4, 1958,
it was noted that "in no other point on the face of the earth has the level of Sr" come close to the level recorded
in New York."
U.S.A. At the Naval Research Laboratory in Washington, a phosphorescent powder (calcium sulfate-man-
ganate) has been developed which is capable of registering infinitesimally small radiation dosages, down to
0.0001 roentgen. The irradiated powder fluoresces (with an intensity proportional to the dose) only when heated
and the fluorescence may be studied several hours after the exposure. The novel substance has already won
application for dosage monitoring in medical applications of x-rays.
France. EDF-1, a gas-cooled, graphite-moderated reactor operating on natural uranium fuel, is being
set up at Chinon (on the Loire). Electric power delivered by the reactor will be 60 Mw, uranium charge will be
120-140 tons. Start-up of the reactor is scheduled for the end of 1959 or early 1960.
France. Starting with 1959, France will be producing about 100 kg of plutonium annually. Pu production
will be carried out by the industrial reactors G-2 and G-3, delivering 200 Mw thermal power each, and specially
built for Pu production.
Sweden. A separation plant for the electromagnetic separation of isotopes, operated since 1948 by the
Nobel Institute of Physics, has been redesigned to give greater resolving power at higher mass numbers (Arkiv
for Fysik 13, 13, 145-163, 1958). Resolving power after the plant was remodeled equaled 1400.
Czechoslovakia. An industrial 15 Mev betatron commenced operation toward the end of 1957 (JadernA
Energie 4, 4, 85-92, 1958).
Japan. Japanese specialists returning from Antarctica announced the discovery of pitchblende and pegmatite
in an area located 40-80 km to the south of Omgul island.
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BIBLIOGRAPHY
E. Teller and A. L. Latter, Our Nuclear Future facts, dangers, and
opportunities. Criterion Books, New York, 1958.
This book discusses the principal facts concerning nuclear energy, its peaceful and military utilization,
the dangers from radioactivity and the argument in favor of nuclear war and the continuation of atom bomb
tests. A list of the chapters will give an idea of the content of the book: I. The Need to Know. II. Atoms.
III. Nuclei. IV. The Law of the Radioactive Decay. V. Splitting of the Nucleus. VI. Reactions Between
Nuclei. VII. Fission and Chain Reactions. VIII. The Effect of Radiation on Matter. IX. Tests. X. The
Radioactive Cloud. XI. From the Soil to Man. XII. The Danger for Individuals. XIII. The Danger for the
Race. XIV. The Cobalt Bomb. XV. What About Future Tests? XVI. Can Anything Happen to the Weather?
XVII. The Safety of Nuclear Reactors. XVIII. Side-Products of Nuclear Reactors. XIX. The Nuclear Age.
The book aims to convince American citizens of the need for atomic weapons and therefore of the need
for continuing the tests. The authors admit that 'the majority of people turn with horror from the question as to
how the existence of atomic weapons affects the coexistence of nations' (p. 169). 'The great and universal need
for peace creates the desire for disarmament. In the minds of the majority of people a cessation of the tests
would be an important step toward disarmament' (p. 139).
Thus in the path of nuclear war and a continuation of the tests there stand the feelings ' . . of all think-
ing and honest people on the earth' (p. 139). In order to counteract these feelings and to overcome the resist-
ance of all thinking and honest people on the earth ,Teller and Latter have written this book, "Our Nuclear
Future". The book contains a review of the physical and biological problems and of the agitation for the con-
tinuation of the tests and for a "small" nuclear war (the authors reject a large nuclear war because of the in-
evitable retaliation).
The chapters of the book which contain a popular scientific account of the principal facts of nuclear physics
are written simply, clearly and briefly. Complicated physical matters are explained without a single equation
yet with accurate concepts. Recent material is introduced boldly (on nonconservation of parity, on the fission of
californium 254 as a source of energy in supernovae, etc.).
The chapters concerning the dangers of radioactivity show the clear slant resulting from the previously
noted purpose of the book, which is to convince one of the safety of the tests. This slant led to an uncritical
review of the subject of the authors. In speaking of strontium shielding coefficients (Ch. XI), that is, the re-
duction of the concentration of strontium relative to calcium upon passage from the soil through plants into the
human organism, the authors present only cases of a high shielding coefficient in dairy products. This high co-
efficient results from the action of the root system of plants and especially of the cow's organism; these two
"filters` reduce the strontium concentration to 1/10.
The authors do not mention that cereal crops, which lack a "filter," are in a worse position and are con-
taminated by direct deposition from the air; the ratio of strontium to calcium concentration here can be 10 times
greater than in the case of dairy products. In countries which consume a great quantity of grains the amount of
strontium which enters the human organism can exceed by one order of magnitude the corresponding amount in
countries which consume a large amount of dairy products.*
In characterizing the state of infection of the bones with strontium 90,Teller and Latter give only averaged
figures?the average for the population and the average over the entire skeleton. As physicists they should not have
neglected fluctuations and the statistical distribution of these quantities.
* Results and interpretation by B. V. Kurchatov.
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From an article of the A merical biologists, Kulp, Eckelmann and Schulert [1], it is known that the dis-
tribution of persons with respect to their strontium content is not Gaussian and is characterized by a large per-
centage of great deviations from the mean. In 1.80/0 of the cases the strontium content of the bones (among
adults in the USA) is ten times as large as the mean. Let us remember that 1.8% of the total population
of the earth would be 50 million people. It can be said that we can still not be sure of this result since the
number of investigated cases is small. Still,this is the only published information about the distribution of
strontium content and there is no basis for ignoring it.
There is still another omission in connection with fluctuations. The authors do not take into account the
nonuniform distribution of the strontium in the bones. In man strontium collects mainly in the vertebrae, where
its concentration is four times greater than the average for the entire skeleton. All countries follow a rule for
calculating the permissible level of irradiation from radio-isotopes within the organism from the point of greatest
irradiation, the so-called 'critical organ," where the greatest concentration of the isotope is found. Thus, if the
organism contains iodine, which accumulates in the thyroid gland, we take into account only the irradiation of the
thyroid gland although its weight is only 20 g. In the case of strontium the "critical organ" would be the vertebrae
rather than the entire skeleton. Furthermore, it is known that strontium in the bones forms pockets so that the
standard dose of strontium is customarily increased by a factor of 5.
Thus the level of irradiation given in the book (p. 118) must be increased by a factor of 4 due to the
"critical organ" (vertebrae rather than the skeleton) and by a factor of 5 because of pocket formation by strontium,
thus by a total factor of 20. For a large portion of the population this level must be increased further by approxi-
mately 10 times (according to the statistical distribution). Then the highest level of irradiation of the bones of
adults for a large portion of the population is (from the original data of the article by Kulp et al.) 0,08 r/year
(instead of the average figure given by Teller and Latter of 0.0003 r/year). These figures are lower than the
natural background (0.18 r/year) but are not as negligible as Teller and Latter state.
Only in calculating the average number of illnesses, whose probability is proportional to the average dosage
of the bones, can we use the average values of the strontium content, as is done by the authors. They estimate
the number of cases of leukemia at 400 per megaton. But this is really the lower limit of the possible number of
cases. Other estimates are a few times larger, especially if we take into account the reduction of the strontium
shielding coefficient in countries with a cereal diet..
The authors neglect to consider the genetic victims, the number of which must be approximately 4000 per
megaton [2]. They also greatly reduce the predictions of contamination, and for a continuation of the tests at the
present rate assume an increase of the level of contamination by a factor of 5 (p. 118). A calculation shows [3]
that the limit of contamination will be 50 times higher than the present level while the level in 1972 will be
13 times higher. The dosage of the vertebrae in 1972 for a large portion of the population will be 16-60% of
the official standard and can be even greater in countries where cereal products predominate in the diet.
Every trained person knows that we cannot permit a large fraction of the population to approach the
official acceptable radiation tolerance.
Let us admit that it can be disputed whether the number of victims per megaton is 4000 or 400, whether
the level of irradiation of the bones with a continuation of the tests increases by a factor of 50 or 5 and whether
the level of irradiation of the bones approaches the official standard or not. Even the obviously exceedingly low
estimates of the authors of this book do not justify their conclusion regarding permissibility of the tests, let alone
of a small nuclear war.
Teller and Latter compare the number of victims of illnesses associated with the tests with the number of
victims of similar illnesses (leukemia and hereditary diseases) resulting from other causes, and find that the
number of, cases resulting from the tests is considerably lower than from other causes and that they are statistically
indistinguishable from other illnesses (p. 170). They compare the reduction of the life span for other reasons of
health (smoking, sedentary life, living in a large city, etc.) with an arbitrary estimate of the reduction of the
life span from the tests and find that the tests have a considerably smaller effect than the other causes (they
. . . are equivalent to the smoking of one cigarette every two months') (p. 124).
Teller and Latter compare the dosage from the tests with the dosage from the natural background and note
that the dosage from the tests is smaller than the latter.
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Their entire argument can be summed up in a single sentence: There are illnesses and circumstances
which lead to a larger number of victims and to a -greater reduction of the life span than result from the tests:
therefore the tests can be allowed. This is a morality and concept of justice which have nothing in common
with what men usually understand. In actuality physicians and society at large regard each cause of the in-
crease of the death rate or detriment to health independently of other causes and attack each cause separately.
Using the argument of the authors physicians could refuse to treat diabetes because there is a more widespread
illness? tuberculosis, and the public authorities could refuse to provide a water supply because smoking occurs.
Any hospital could refuse to assist patients because the result of the illness would be 'statistically indistinguishable"
(p. 120).
Teller and Latter state that although radiation can be hal-mint, it can also he beneficial, because it would
be 'more in accord with the ideals of humanity to strive to improve the life of all mankind,' that is, they assume
that we may destroy a small number of persons through the action of radioactive fallout in the hope that this
effect will be of value to the rest of mankind ,and thus essentially propose a medical experiment on people
without their consent, which is strictly forbidden by all law.
The entire argument of Teller and Latter is based on a small number of victims of the tests compared with
victims of other causes and of natural death. But this small number does not seem, small to the victims them-
selves. The small number of victims is the result of the test explosions, so that each test explosion is a death
sentence for a certain number of persons rendered by others who are completely unauthorized to do so,
As soon as scientific data on the danger of the tests had been accumulated, the Soviet government ter-
minated the tests, thus showing that it is a form of society in which morality and justice determine the behavior
of the government.
To further "convince" their readers of the permissibility and necessity for the tests, the authors discuss the
development of a 'clean" bomb, that is, a bomb in which the energy is emitted in thermonuclear reactions
rather than through nuclear fission. The reaction products of such a bomb contain almost no fission fragments
and in the opinion of the authors it will not present a radioactive danger. The authors declare that it is necessary
to conduct tests for the development of a "clean' bomb and when it is ready it will no longer be necessary to
fear tests and even war will not result in victims of radioactivity.
The idea of the radioactive safety of a "clean" bomb is a pure contradiction in terms. A "clean" bomb
emits several times more neutrons (per unit of energy) than a fission bomb. These neutrons,by reacting with
nitrogen nuclei of the atmosphere, form radioactive carbon-14, with a half-life of approximately 5100 years.
Calculations show [2, 41 that the total amount of energy from the radioactive decay of carbon-14 produced by
a "clean" bomb is three times as large as the total decay energy of cesium-137, strontium-90 and carbon-14
from a fission bomb, At the tolerance limit these energies are equal. An estimate of the number of victims of a
"clean" and of an ordinary bomb shows that the results are practically identical.
The difference between a "clean" and an ordinary bomb lies in the time of the appearance of the harmful
effects? centuries from the explosion of a fission bomb and thousands of years from the explosion of a "clean"
bomb. If it is assumed that our responsibility extends only to the present generation,then "after us the deluge."
so that we can forget about far-off consequences of the explosion of a "clean' bomb. Such an argument would
be fully in the spirit of the other arguments of the authors which have been discussed above.
It is in the nature of people to be concerned about the future. Only opportunistic arguments would allow
illness of the twentieth generation while not allowing illness of the second generation.
Teller and Latter evidently understand the weakness of their argument for convincing readers and finally
state: 'There are many specific political and military reasons for not terminating the tests' (p. 145). This is
the crux of the matter rather than scientific 'proofs" of the permissibility of the tests.
Behind all of this is the policy of certain imperialistic elements in the USA who are preparing to wage an
aggressive nuclear war. In order to begin the war the people must be convinced of its necessity. But this is
impossible since no real argument can be given. Therefore Teller and Latter begin with postulates to the effect
that communistic countries are striving for world domination, that they threaten the security of Americans, thatit
is impossible to come to an agreement with Russia: 'There are no signs that limited wars are ending. We must
prepare effective mobile weapons for such conflicts and this requires the use of nuclear weapons' (p. 170).
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A scientist must remain a scientist even when he leaves the field of his specialty. Only then is his opinion
of weight and his articles significant. If Teller and Latter had regarded human society as scientists, that is,ob-
jectively and with an attempt to find and understand its laws, they would have seen that their "postulates" do
not exist and that no one is threatening the USA. They write: ' ... The future is made by people. People are
unpredictable. Therefore the future is unpredictable.' Nevertheless ,there exists a science of the development of
society and the future can be predicted. The laws of the development of society lead to the recognition that all
countries must have the same right as the USA to independence and security. Then no atomic bomb and no
small or large wars are necessary. It is only necessary to have trade and peaceful rivalry of countries for the
improvement of the lives of all their citizens.
Teller and Latter in their book did not mention this alternative for our nuclear future"; by forsaking the
scientific method,they have made their book worthless.
[1]
LITERATURE CITED
J. L. Kulp, W. R. Eckelmann, and A, R. Schulert, Science 125, 3241, 219 (1957).
[2]
0. I. Leipunskii,LAtomic Energy (USSR)
3,
12, 530 (1957).*
[3]
0. I. Leipunskii,J.Atomic Energy (USSR)
4,
1,
63
(1958).*
[4J A. D. Sakharov,J.Atomic Energy (USSR)
4,
6,
576
(1958).*
0. I. Leipunskii
? Original Russian pagination. See C. B. Translation.
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THE POLISH JOURNAL "NUKLEONIKA" (NUCLEONICS)
(A Review)
Beginning in the second half of 1956 there has been published in Poland the scientific and technical
journal "Nukleonika," which is the organ of the Committee on the Peaceful Uses of Atomic Energy of the Polish
Academy of Sciences. While the first few issues of the journal contained principally translations of articles
from foreign scientific journals, later original articles began to predominate, which were written by Polish
specialists, although the 1957 issues contained articles by well-known foreign scientists who had visited Poland:
D. I. Blokhintsev (USSR), E. Brode (Austria), J. Cockcroft (England), F. Perrin (France) and others.
Among the articles by Polish specialists* which were published in 1957 we must mention "The basic
problems of nuclear power" (V. Frankovskii), "The role of fast-neutron plutonium reactors in the development
of nuclear power" and "Utilization of plutonium dioxide as nuclear fuel" (M. Taube), "Fast-neutron spectro-
metry" (D. O'Connor), "The production of Geiger-Mueller counters in Poland" (A. Ianikovskii), "Radiochemical
laboratories" (R Gvuzd), 'A review of deactivation methods in radiochemical laboratories' (I. Seika), "The
production of radioactive isotopes in Poland" (R. Pleevskii). "The use of radiochemical methods in the investi-
gation of nuclear reactions" (S. Sekerskii), "Methods of determining traces of impurities in reactor materials"
Minchevskii), "Accelerators" (V. Zykh), 'A spherical pistol-type manipulator" (V. Nei), etc.
In 1958 the Journal has devoted much more space than previously to articles on reactor design. These
include, for example: "A plan for the development of nuclear power in Poland" (P. Novatskii), "The first
nuclear reactor in Poland" (Iu, Aleksandrovich and P.Shulets), "Work on the designing of a second Polish re-
search reactor" (K. Koval'skaia), "Reactor graphite' (A. Grossman). In 1958 the journal is conducting a
discussion of methods of developing nuclear power in Poland.
Of original articles by Polish authors on other questions we may mention "On the refining of Polish uranium
ore" (T. Adamskii), "The effect of nuclear radiation on semiconductors' (G. Rzhevuskii), "Chemical shielding
from ionizing radiation" (A. Dantsevich), "On some reaction mechanisms of hot atoms" (I. Kampbell).
Review articles periodically discuss the problems and state of development of the utilization of atomic
energy in different countries. Each issue of the journal contains material on recent developments of nuclear
technology as well as current news. "Nukleonika" can now rightly be regarded as one of the leading scientific
and technical journals of Poland. The intense development of work on the utilization of atomic energy in the
country will make this journal even more important.
M, T.
? The names of Polish scientists appear here as transliterated from the Russian ? Publisher
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RECENT LITERATURE *
Books and Collections of Articles
Reactor design. The list of translated books on nuclear technology which have been published recently
in the Soviet Union now contains two new titles. The Foreign Language Press (IIL) has now translated into Russian
and published the monographs of two outstanding American specialists "The Control of Nuclear Reactors and
Power Plants" by M. Schulz, 1957 (460 pp., 17 r. 60 kop) and "Shielding of Nuclear Reactors" by T. Rockwell,
1958 (337 pp., 26 r. 40 kop).
The first book contains 11 chapters. At the beginning there is a brief resume of the physical basis of the
operations and kinetics of a reactor. Then there is an examination of the automatic regulation of reactors and
nuclear power plants, the mechanisms of a reactor control system, the start-up systems, operation at rated power
level and shut-down. Much attention is devoted to the problems of models of reactor processes and loops for the
removal and utilization of heat. Finally, a description is given of radiation detectors which are used for control
of reactors.
The second book is a handbook with wide coverage of all the problems associated with the designing and
planning of the shielding of nuclear power reactors. The book contains 10 chapters. The first few chapters
discuss the fundamental methods of solving shielding problems and give the basic concepts, definitions and units
for measurements of radiation. The following chapters cover the shielding of the reactor core, radioactive heat
generation in the shielding, the activation of coolants and the shielding of heat-transfer loops. Considerable
space is devoted to shielding materials and the geometry of radiation sources. A special chapter is devoted to
the least fully developed question of the influence of irregularities on shielding (gaps, cavities in tubing, etc.).
The book contains rich factual material., in the form of tables, graphs and nomograms. Although the bbok does
not treat all problems fully, it is a useful aid for the designers of reactor shielding.
A large number of American specialists in the various fields participated in the writing of both books. t
Therefore, they reflect contemporary achievements and the state of reactor technology. Since Soviet readers
as a whole have not thus far had literature of this kind available,these two books will to a considerable degree
fill the gaps which exist. For specialists these books can serve as useful reference works.
Problems of nuclear power. Collections of translations and reviews of foreign periodical literature, No. 1,
1958, IIL, 106 pp., 8 r. 40 kop.
The section on Power Plants and Layouts contains translations of the articles "Thermal problems of atomic
power stations" from Combustion 28, 8, 51 (1957); 28, 12, 51 ,(1957) and "A boiling-water reactor with an
intermediate heat exchanger' from Nucl. Power 2, 17, 369 (1957).
The section Designs and Materials contains translations of the articles "Heat exchangers for atomic power
plants" from Heat Eng. 32, 2, 30 (1957), "The utilization of organic compounds as moderators and coolants in
nuclear reactors" from Atomkernenergie 5,176 (1957) and "Magnetic jack?a new control drive mechanism'
from Nucleonics 15, 6, 118 (1957).
The section Transfer Processes contains translations of the articles "Chemical problems in the use of gas
coolants" Nucl. Eng. 2, 17, 321 (1957), 'Activity transport in sodium-cooled systems" from Nucleonics 15, 2,
58 (1957), "The selection of a coolant for a high-temperature reactor' from Nucl. Power 2, 17, 381 (1957),
"The problem of corrosion caused by water at high temperatures in nuclear reactors" from Atomkernenergie 6,
207 (1957); 7. 248 (1957), 'The water system of pressurized water reactors (PWR)? from Engineers Soc. of
Western Pennsylvania, Proc. Seventeenth Annual Water Conference, October, 1956.
* The titles of non-Russian works appear here as translated from the Russian. The wording may therefore
differ from that of the originals.? Publisher.
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The section Nuclear Power News contains translations of the articles "Fuel elements of the Calder Hall
power plant" from Nucl. Power 2, 17, 394 (1957), 'Tubes for heat exchangers" from Nucl. Power 2, 18, (1957),
"A discussion of fuel elements" from J. Brit. Nucl. Energy Conf. 2, 3 (1957).
Methods of determining the radioactive elements in ores. Gosgeoltekhizdat, 1958, 70 pp. 2 r. 20 kop.
A collection to the chemical determination of radioactive elements in minerals and rocks. Working instructions
for the various methods are given.
Science News. Radiobiology. Biological Effects of Ionizing Radiation, Vol. 1, ?A. M. Kuzin, Ed.,
Academy of Sciences Press, 1957, 436 pp. 19 r. This book is a critical review of articles on radiobiology from
1935 to 1955, which form a very extensive literature both at home and abroad.
Shielding of Personnel against Ionizing Radiation. Translated from English by L. B. Prokhorova, IlL,
1958, 182 pp. 7 r. 80 kop. This book provides information regarding infections due to radiation, tolerances
and the methods of shielding personnel.
Lebedinskii, A. V., The Effects of Ionizing Radiation on the Living Organism, ?Znanie" Press, 1957,
56 pp., 1 r. 20 kop. This pamphlet is devoted to one of the most important problems of modern science ?
the effects of various forms of ionizing radiation (x-rays; alpha, beta, and gamma rays; neutron flux) on the
living organism.
Mikhailov, V. A., The Physical Foundations of the Production of Atomic Energy, 2nd revised and en-
larged edition, Voenizdat, 1958, 176 pp., 2 r. 75 kop. This is a popular presentation of the physical founda-
tions of the production and utilization of atomic energy for both peaceful and military purposes.
Articles in Journals
Agranat, V. Z., On the accumulation of radioactive polonium (Po 21?) in aqueous forms, Meditsinskaia
radiologiia 3, 1 (1958).
Breslavets, L. P., Radioactive emissions in agriculture, Priroda 3 (1958).
Vordoberg, D. B. et al., Atomic energy. ( A general review of foreign countries for 1956-1957). Power
production abroad. Supplement to the journal "Eleketricheskie stantsii".
Gell-Mann, M. and Rosenbaum, E., Elementary particles, Uspekhi fiz, n auk 64, 2 (1958) [Russian
translation].
Graevskii, E. Ia. and Zinov'eva, E. G., On the possibility of altering the radiosensitivity of cells by
means of fluorochromes, Doklady Akad. Nauk SSSR 118, 3 (1958).?
Grik, B. et al., Extraction of uranium from phosphoric acid, Khimia i khim. tekhnol.
(Condensed translation from foreign period. Lit) 2 (1958).
Denisoy, N. G., On the resonant absorption of electromagnetic waves by an inhomogeneous plasma
(letter to editor), J. Exp. Theoret. Phys. 34, 2 (1958).4'1'
Zakutinskii, D. I. Problems in the toxicology of radioactive substances, Meditsinskaia radiologiia 3,
1 (1958).
Kovalev, V. P., Measurement of the fissimrneutron spectra of U233, U 235, and Pu 239 from 50 to 700 key
( letter to editor), J. Exp. Theoret. Phys. (USSR) 34, 2 (1958).**
Kosta, L., Separation of Th294 from uranyl nitrate, Khimia i khim. tekhnol. (Condensed translation from
foreign period. lit.) 2 (1958).
Kuznetsov, E. V., Bubble chambers, Uspekhi fiz. nauk 64, 2 (1958).
Kuz'minov, B. D. and Smirenkin, G. N., Systematics of the average number of prompt fission neutrons
v (letter to editor), J. Exp. Theoret. Phys. (USSR) 34, 2(1958). **
? See C. B. Translation.
* ? See English Translation.
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Marei, A. N. et al., On the transfer of radioactive strontium from open reservoirs to the human organism,
Meditsinskaia radiologiia 3, 3 (1958).
Perlin, I. L. et al., Compression of beryllium, zirconium, uranium, and thorium (from the literature),
Tsvetnye metal. 2 (1958).
Pik-Pichak, G. A., Fission of rotating nuclei, J. Exp? Theoret. Phys. (USSR) 34, 2 (1958).*
Pipperd, D. et al., Separation of tetravalent berkelium by extraction with solvents, Khimia
i khim. tekhnol. (condensed translation from foreign period, lit.) 2 (1958).
Protopopov, A. N. and Shiriaev, B. M., Investigation of gamma rays accompanying the fission of U 238
by neutrons from 2.8 to 14.7 Mev, J. Exp. Theoret. Phys. (USSR) 34, 2 (1958).*
Sinel'nikov, K. D. et al., Separation of isotopes in unsteady molecular flow, J. Exp. Theoret. Phys.
(USSR) 34, 2 (1958).1'
Stepanov, V. G. et al., On rotating plasma (letter to editor), J. Exp. Theoret. Phys. (USSR) 34, 2 (1958).?
Tarantin, N. L et al., Mass distribution of fission products from the irradiation of gold and uranium with
nitrogen ions, J. Exp. Theoret. Phys. (USSR) 34, 2 (1958).4'
Anderson, 0. A. et al., Phys. Rev. 109, 2, 612 (1958). Neutron production in linear deuterium pinches.
Barton, G. B. et al., Ind. Eng. Chem. 50, 2, 212 (1958). Recovering fission products (cesium).
Bengston, J., Nucl. Sci. Eng. 3, 1, 71 (1958). Self-shielding of neutrons in a simple two-dimensional
lattice.
Bernstein, I. B., Phys. Rev. 109, 1, 10 (1958). Waves in plasma in a magnetic field.
Blaise, S. et al., J. phys. radium 19, 1, 66 (1958). Measurement of the average number of neutrons
emitted in U 238 fission by 14.2 Mev neutrons.
Bochinski, J. et al., Ind. Eng. Chem. 50, 2, 157 (1958). Separation of monazite rare earths by solvent
extraction.
Bock, R. et al., Z. angew. Phys. 10, 2, 49 (1958). A single-dee constant-frequency cyclotron.
Bolt, R. 0. and Carroll, J. G., Ind. Eng. Chem.
oils.
50,
2,
22 (1958).
Radiolysis and radiolytic oxidation of
Burger, L. L. and McClanahan, Ind, Eng. Chem.
and its diluent systems.
50,
2,
153 (1958).
Gamma radiolysis of tributyl phosphate
Butler, J. W. and Grotenhuis, Nucl. Sci. Eng. 3, 1, 47 (1958). Activity decay of fission products in reactor
cycling.
Chiotti, P. and Shoemaker, Ind. Eng. Chem. 50, 2, 137 (1958). Pyrometallurgic separation of uranium from
thorium.
Codding, J. W. et al., Ind? Eng. Chem. 50, 2, 145 (1958). Tributylphosphate - hydrocarbon systems.
Cox, R. P. et al., Ind. Eng. Chem. 50, 2, 141 (1958). Separating hafnium from zirconium (solvent extraction
with tributyl phosphate).
Davis, M. V., Nucl. Sci. Eng. 3, 1, 107 (1958). Temperature coefficient for fuel elements with U 238.
Dio, W. H. and Schopper, E., Nucl. Phys. 6, 2, 175 (1958). Temperature dependence of the diffusion co-
efficient and the diffusion length of thermal neutrons in water.
Diven, B. C. et al., Phys. Rev. 109, 1, 144 (1958). Capture to fission ratios for fast neutrons in U 238.
Dykstra, J. et al., Ind. Eng. Chem. 50, 2, 161 (1958). Solvent extraction system for enriched uranium.
? See English Translation.
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Dykstra, J. et al., Ind. Eng. Chem. 50,2, 181 (1958). A 25-pound-per-hour fluorine plant,
Edwards, S. F., Phil. Mag. 3, 27, 302 (1958). Correlations in the charge density of a classical plasma.
Evans, J. B. et al., Ind. Eng. Chem. 50, 2, 192 (1958). Chemical effects of nuclear transformations.
Foley, D. D. and Filbert, R. B. Jr., Ind. Eng. Chem. 50, 2, 144 (1958). Purifying thorium nitrate by
solvent extraction (with tributyl phosphate).
Fuger, J., J. Nucl. Inorg. Chem. 5, 4, 338 (1958). Ion-exchange behavior and dissociation constants of
Am, Cu, and Cf combined with ethylenediaminetetraacetic acid.
Fulmer, C. B. and Cohen, B. L., Phys. Rev. 109, 1, 94 (1958). Equilibrium charges of fission fragments
in gases.
Gallagher, T. L., Nucl. Sci. Eng. 3, 1, 110 (1958). Self-shielding in detectors made of food wrappings.
Goodman, E. I., Ind. Eng. Chem. 50, 2, 210 (1958). A radio tracer for studying sewage distribution.
Greer, A. H. et al., Ind. Eng. Chem. 50, 2, 166 (1958). A new ion-exchange resin for uranium recovery.
Henry, A. F., Nucl. Sci, Eng. 3, 1, 52 (1958). Application of reactor kinetics to the analysis of experi-
ments.
Hotten, B. W. and Carroll, J. G., Ind. Eng. Chem. 50, 2, 217 (1958). Radiation damage in lubricating
greases.
Hubbs, J. C. et al., Phys. Rev. 109, 2, 390 (1958). Hfs measurements on Pu 239.
Huizenga, J. R., Phys. Rev. 109, 2, 484 (1958). Correlation of competition between neutron emission
and fission.
Hull, D. E., Ind. Eng. Chem. 50, 2, 199 (1958). (Measurement of the velocity of flow with radioactive
tracers). Total-count technique in the refinery.
Hurwitz, H. and Nelkin, M. S., Nucl, Sci, Eng. 3, 1, 1 (1958). Thermal neutron spectrum in a diffusive
medium.,
Kasten, P. R. and Aven, R. E., Ind. Eng. Chem. 50, 2, 171 (1958). Fuel costs in batch and continuous-
processed homogeneous reactors.
King, W. H. Jr., Ind. Eng. Chem. 50, 2, 201 (1958). Radioisotopes in petroleum refining.
Lonati, R. et al., Nuovo cimento 7, 2, 133 (1958); Investigation of very weak alpha-radioactivity.
Magnac-Valette, D. et al., J. phys. radium19, 1, 88 (1958). A 340-key accelerator for investigating
reactions induced by tritons.
Margenau, H., Phys. Rev. 109, 1, 6 (1958). Conductivity of plasmas to microwaves.
McMurray, H. L, et al., Nucl. Sci. Eng. 3, 1, 38 (1958). Estimation of the length of runs of reactors
with small cores.
Milford, R. P., Ind. Eng. Chem. 50, 2, 187 (1958). Engineering design of Oak Ridge fluoride volatility
pilot plant. ?
Moore, J. A., Phys. Rev. 109, 2, 417 (1958). Resonance scattering of slow neutrons in In.
Mueller, R. H., Ind. Eng. Chem. 50, 2, 205 (1958). Interaction of beta rays with matter.
Osborn, R. K., Nucl. Sci. Eng. 3, 1, 29 (1958). Some properties of the thermal-neutron scattering
probability.
Ranftl, J. W., Ind. Eng. Chem. 50, 2, 196 (1958). Using electrons in chemical processing.
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Rosenbluth, M. N. and Kaufman, A. N. Phys. Rev. 109, 1, 1 (1958). Plasma diffusion in a magnetic
field.
Strickler, T. D. et al., Nucl. Sci. Eng. 3, 1, 11 "(1958). Fast-neutron scattering in thick plates.
Vavalides, S. P. et al., Ind. Eng. Chem. 50, 2, 178 (1958). High-capacity long-life fluorine cell.
Werner, F. G. and Wheeler, J. A., Phys. Rev. 109, 1, 126 (1958). Superheavy nuclei.
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SIGNIFICANCE OF ABBREVIATIONS MOST FREQUENTLY
ENCOUNTERED IN SOVIET PHYSICS PERIODICALS
AN SSSR
FIAN
GITI
GITTL
GOI
GONTI
Gosenergoizdat
Gosfizkhimizdat
Gozkhimizdat
GOST
Goztekhizdat
GTTI
GUPIAE
IF KhI
IFP
IL
IPF
IPM
IREA
ISN (Izd. Soy. Nauk)
I YaP
Izd
KISO
LETI
LET'
LIM
LITMi0
Mashgiz
MATI
MGU
Metallurgizdat
MOPI
NIAFIZ
NIFI
NIIMM
NII ZVUKSZAPIOI
NIKFI
OIYaI
ONTI
OTI
OTN
RIAN
SPB
Stroiizdat
URALFTI
Academy of Sciences, USSR
Physics Institute, Academy of Sciences USSR
State Scientific and Technical Press
State Press for Technical and Theoretical Literature
State Optical Institute
State United Scientific and Technical Press
State Power Press.
State Physical Chemistry Press
State Chemistry Press
All-Union State Standard
State Technical Press
State Technical and Theoretical Press
State Office for Utilization of Atomic Energy
Institute of Physical Chemistry Research
Institute of Physical Problems
Foreign Literature Press
Institute of Applied Physics
Institute of Applied Mathematics
Institute of Chemical Reagents
Soviet Science Press
Institute of Nuclear Studies
Press (publishing house)
Solar Research Commission
Leningrad Electrotechnical Institute
Leningrad Institute of Physics and Technology
Leningrad Institute of Metals
Leningrad Institute of Precision Instruments and Optics
State Scientific-Technical Press for Machine Construction Literature
Moscow Aviation Technology Institute
Moscow State University
Metallurgy Press
Moscow Regional Institute of Physics
Scientific Research Association for Physics
Scientific Research Institute of Physics
Scientific Research Institute of Mathematics and Mechanics
Scientific Research Institute of Sound Recording
Scientific Institute of Motion Picture Photography
Joint Institute of Nuclear Studies
United Scientific and Technical Press
Division of Technical Information
Division of Technical Science
Radium Institute, Academy of Sciences of the USSR
All-Union Special Planning Office
Construction Press
Ural Institute Of Physics and Technology
NOTE: Abbreviations not on this list and not explained in the translation have been transliterated, no
further information about their significance being available to us.?Publisher.
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recent Russian research
I
in complete English translation II
A Supplement
- to
"HELIUM"
BY E. M. LIFSHITS
AND E. L. ANDRONIKASHVILI
M HIS NOTABLE volume consists of two
supplementary chapters, by these out:
standing Soviet physicists, which were
added to the Russian translation of W. H.
Keesom's Classic book "HELIUM."
The first chapter, by Lifshits, is a con-
cise resume of the Landau theory of
superfluidity (quantization.of the mo-
tion of a liquid; superfluidity of Heli-
um II; macroscopic hydrodynamics of
Helium II). The second chapter reports '
in considerable detail the experimental
work conducted by Peter Kapitza and
E. L. Andronikashviii in this field
( motion of Helium II due to the influx
'of heat; the two forms of motion in
Helium II; viscosity of the normal com-
ponent; reversibility of 'hydro-thermal
processes and the therrno-mechanical-
effect; critical :velocities; heat trans-
port in slits and capillaries; heat trans- -
port in free Helium II; second sobnd;
films; impurities).
Recent eiperiments on the superfiuidity ? --
of helium make A SUPPLEMENT TO.
- "HELIUM" of major interest to all re-
searchers in low temperature physics.
cloth bound ? i75 pages ? $7.50
(13 translations are by bilingual scientists,
and include all photographic; diagrammatic
and tabular material integral with the text.
Complete Table of Contents -N
SUPERFLUIDIT
- QUANTIZATION OF THE MOTION OF
A LIQUID
Helium Il?a quantum liquid ? energy spectrum
of a quantum liquid ? energy spectrum of an
almost-ideal Bose-Einstein gas ? calculation of
-the thermodynamic properties of Helium II
SUPERFLVIDITY OF HELIUM II
superfluidity of Helium II at absolute zero ?
Helium II at temperatures above absolute zero
? calculation of the iatio.pnbo ? heat transport
Y (THEORY)
in Helium'!! ? mechano-caloric effect in Helium
II ? effect of impurity atoms in Helium II
MACROSCOPIC HYDRODYNAMICS
OF HELIUM II'
system of hydrodynamic equations for Helium
II ? hydrodynamic equations for an incompres-
sible liquid ? propagation of sound in Helium
II ? radiation of sound in Helium II ? effect of
impurities on the piopagation of second sound
in Helium II ? scattering of,?light in Helium II
? viscosity of Helium rt ? the Tisza theory of
Helium II
SUPERFLUIDITY (EXPERIMENTAL DATA)
MOTION OF HELIUM IS
DUE TO THE INFLUX OF HEAT
Introduction ? heat transport in Helium II mov-
ing in a Capillary ? nature of the jet and the
jet profile.* reaction of the jet ? heat transport
in free Helium II?radiometer effect ? discus-
sion of the results?heat transport mechanism
in Helium Il
THE TWO FORMS OF MOTION
IN Enund II
iormulation of the problem ? description of the
experiment results of the experiment ? dis-
cussion of the results
VISCOSITY OF THE
? . NORMAL COMPONENT
the notion of viscosity in Helium II ? critique
of the earlier experiments ? determination of
? viscosity from experiments in which two forms
of motion are observed ? determination of the
viscosity of the normal component from experi-
..menttiwith heavy disks ? determination of the
- viscosity of the normal component fromexperi-
ments on heat transport in slits ? discussion
- of the results
REVERSIBILITY OF HYDRO-THERMAL
PRodEsses AND -
THE THZRMO-MECHANICAL Errfer
heat content of Helium II ? thermo-mechanical
effect and reversibility of hydro-thermal proc-
esses ? new method of obtaining low tempera-
tures ? therino-mechanical effect and the vis-
cosity of the superfluid component ? discussion
-of the results
_
CRITICAL VELOCITIES
. critical velocities and wall films. critical veloc-
ities in thin slits and capillaries ? critical veloc-
ities in wide slits ? discussion of the results
- HEAT TRANSPORT IN SLITS
AND CAPILLARIES
general remarks ? apparatus * wide slits ? nar-
row slits ? discussion of results
HEAT TRANSPORT IN TREE HELIUM'ZI
Introduction ? optical observations of the heat
transport process ? temperature distribution
close to a heat disseminating surface ? discus-
sion of results
SECOND SOUND
introduction ? generation of second sound by
the _thermal method ? filtration method ? con-
version of second sound to first sound ? second
sound under conditions of high pressure ? die-
- mission of results
FILMS ? .
film thickness ._vapor pressure abOve the film
? thermo-mechanical and mechano-caloric ef-
fects in films ? motion of a film without gravi-
tational forces ? momentum of the film ? prob.
lem of film formation from the gas phase
IMPURITIES
behavior of col101ds in Helium II ? the HO iso-
tope ? separation of helium isotopes by ero-
genic techniques ? distribution Of the Het iso-
tope between two phases of the solvent ? dis-
cussion of results ? other properties of a solution
of Het, in He4 ? separation of helium isotopes'
by the thermal diffusion method
CONSULTANTS BUREAU, INC.
227 WEST 1711:1- STREET, NEW YORK 11? N. Y
-
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Announcing A NEW expanded program for the translation
and publication of s i x leading Russian physics
journals: Published by the American Institute of Physics with- the -
cooperation and support of the National Science Foundation. .
SOVIET PHYSICS ? TECHNICAL,PHYSICS. A translation of the "Journal
of Technical Physics" of the Acaderily of Sciences of the U.S..S.R. 12 issues
per year, Vol.-3 begins July 1958, approximately 3,000 Russian pages.
Annually $75.00 domestic.
SOVIET PHYSICS ? ACOUSTICS. A translation Of the "Journal of Acoua-
tics " of the Academy of Sciences of the U.S.S.R. Four issues per year,
Vol. 4 begins July 1958; approximately 400 Russian pages.Annually $12.00
domestic.
SOVIET PHYSICS -2DOKLADY. A translation of all the "Physics Section"
of the Proceedings of the Academy of Sciences of the U.S.S.R. Six issues
per- year,, Vol. 3 begins July 1958,, approximately 800 Russian paged:
Annually $35.00 domestic. -
SOVIET PHYSICS ?jETP. A translation of the "Journal Of Experiinental
and Theoretical Physics" of the Academy of Sciences of the U.S.S.R. Twelve
Issues per year; Vol. 7 begins. July 1958, approximately 3,700 Ruasian
page's. Annually $75.00 domestic.
SOVIET PHYSICS Crystallography. A translation of the journal "Crystal-
lography" of the Academy.of SCiences,of the U.S.S.R. -Six issues per year,
Vol. 2 begins July: 1958, approximately 1,000, Russian pages. Annually
$25.00 domestic. . .
SOVIET ASTRONOMY ? AJ. A translation of the "Astronomy Journal" of
the Academy/of ?Sciences of the U.S.S.R. Six issues per year, Vol. r begins
July 1958, approximately 1,209 Russian pages. Annually-$25.00 domestic.,
Back issues are available, either in complete sets or single -copies.,
All 'journals are to be complete translations of their Russian counterpane'.
The number 'of pages to be published represents the best estimate based on
all available' information now on hand.
Translated by conipetent, qualified scientists, the publications will provide
all research laboratories and libraries with accurate and up-to-date infor-
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Declassified and Approved For Release 2013/09/13: CIA-RDP10-02196R000100010005-8