RADIOACTIVITY IN THE SOUTHERN STRATOSPHERE
415
Table 2— FORMATION ACTIVITY RATIOS FOR
FISSION PRODUCTS FROM A TYPICAL
THERMONUCLEAR DEVICE
Nuclide ratio,
B/A
10R9/57r
8Sr/57Zr
Hy/57r
57r/4Ce
14ce/Msr
BICs/MSr
Formation
activity
ratio, Z
5.2
0.65
Ratio half-life,
days [In 2/(Agp—Aa)]
15.9
227
0.82
4,7
639
84
1.45
~105
48
293
CONTRIBUTIONS FROM THE 1961 U.S.S.R. TESTS
The concentration profiles for total *“Sr at 34°S are given in the
second column of Table 3 for several periods in 1962 and 1963. The
calculated fractions attributable to the 1961 U.S.S.R. test series are
given in the third column.
The results indicate that 1961
debris was present in the lower
stratosphere in the first half of 1962, accounting for a few percent of
the total “Sr. It was undetectable above 70,000 ft although a few high,
but suspect, '‘ce/*Sr values suggest that traces might have been
present at 105,000 ft. The fresh debris accounting for increased gamma
activity concentrations at 65,000 and 80,000 ft in August and September
was due to the Dominic I series, April through July 1962, that in-
creased the “sr levels just slightly above that attributable to pre-1961
debris. Only for the latter part of the year at 65,000 and 105,000 ft is it
possible to assign more than 10% of the Sr to the 1961 tests, as may
be seen from the December data. Although the higher gammaactivity
concentration at 105,000 ft may in part be explained as being attributed
to the 1961 debris, the larger fraction of postmoratorium material at
this latitude came from 1962 tests.
Additional Sr from 1961 tests at the high altitudes sampled is
suggested by the April 1963 data. However, it was in June at 77,000 and
86,000 ft, when the gamma activity concentrations were at their peak
and the total ®°Sr had increased by a factor of 5 over April levels, that
the largest amounts of 1961 debris appeared to be present: up to 500
dis/min per 10° scf.
Conclusions about these levels of 1961 U.S.S.R. debris must be
reserved until evidence that the fission-product formation ratios for a
typical device which were used in the calculations approximate the
average for weapons detonated in 1961 and 1962. If, for instance, the
average ‘“4ce/*"Sr ratio for Dominic I was 40 instead of 48, it is pos-