612
KURODA, KAURANEN, PALMER, MENON, AND FRY
have been carried out by Dorn? and by Hoff and Dorn”! on the basis of
transuranium-element production. The results indicate an exposure
of material to the order of several times 10% neutrons/cm?’ with neutron energies ranging from thermal « 10 kev in the bomb) to more than
14 Mev. Up to 17 succeSsive neutron captures have been found to take
place in exposed uranium. It is easy to show that an exposure of this
magnitude will provide for a large amount of multiple neutron capture in
antimony, even if a fast-neutron-capture cross section of only 0.1 barn
is used for the antimony isotopes,”
It may be also pointed out in this
connection that the samples
collected in 1963 which are high in '4Sb content do not show exceptional
23Sb content. This indicates that the '*4Sb produced in late 1962 originated in a lower neutron flux.
Figure 6 shows thedistribution of ‘4Sb in Apriland July 1963. High
24Sh concentrations occurred also in the middle and tropical latitudes
during the spring and summer of 1963, generally at somewhat higher
altitudes than in the polar samples. The concentration isolines have an
upward slope from the polar to the tropical stratosphere, and a clear
increase of the '*4Sb content in the tropical stratosphere can be observed between April and July. If nuclear tests in the polar strato-
sphere were the only sources of '*4Sb, these findings would give strong
Support to the theory of eddy diffusion for the horizontal transport of
material in the stratosphere, as described by Newell’® and Friend
et al.*4 It would apparently be difficult to explain the southward move70
go
=
|
Poy fF
19,400
we
1650
NL
< 150s. SN
< 60
eS
50
53,100
‘.
‘NS
—
4
Ro
240
0
20
it |
Jf
30°N
TTT
24,500
650
��
1,640
~s
“AL
A
< 130
< 70
| td
LATITUDE
60°N
~~
90°N O°
7,130
“SL
Lag?
~]
“
285
e
>> le 2
ee—“,,
JULY 1963
IL
{|
£
30°N
_|
~~~- 104
TROPOPAUSE
“|
~
53,400
_
= es
Wo
15
ft
oT
a
u
see
APRIL 1963
oP
go
7.750 ~~s!
Ton 4540S
oe
"Or,
<
yoo
mS
~~~ 194
“S
-
toy
oF. ~~
62,600
N
S
+
YN
*
< 200
Oo
~
< 320
} oT.
f{
ft
LATITUDE
{[
60°N
ff
Fig. 6 —1*4Sb concentrations in the atmosphere in April and July 1963
in disintegrations per minute per 10° scf. Tropical (~10°N) and middle
(~30°N) latitude values are estimated from gross gamma-ray spectra.
=
|
90°N