- 19 -
MEV escape peak of wi85 were found in the gamma spectrum (Fig. 5).
A maximum beta energy of 0.43 MEV was determined by the mass
absorption technique; the half life, determined by beta counting,
was found to be approximately 70 days.
Plant-leaf samples collected at Janet Island on April 28,
at Belle Island on May 10 (Fig. 6, Tables 2, 3) and at Henry
Island on May 8, did not contain wi85; cs137 was the only gamma
emitter present.
However,
plant-leaf and soil samples collected
at the same islands during June and August did contain radiotungsten.
Samples of pulverized coral were taken June 5, 1958, from
the crater of a nuclear device detonated near Janet Island on
May 26.
The results of gamma spectrum analyses on this material
from the target area are shown in Tables 2 and 3.
gamma emitters were detected:
Rut03-Rn103,
wi8s,
cel41_pyl41 |
Rut06_pp106 and Zr95-Nb9?.
Only six
celt4_pplt4 |
The disintegration rate
of wi85 per gram of sample was 3,500,000 d/m and accounted for
67 per cent of the total radioactivity.
In top soil from Belle
Island collected August 20, approximately four and one-half
miles from ground zero,
wi85 contributed 68 per cent of the
total radioactivity (13,000,000 d/m/square inch of top soil)*.
* Two types of surface soil samples were taken -- top
top two inches.
In the top inch samples, one cubic
soil was considered to represent one square inch of
surface.
In the two-inch samples, two cubic inches
assumed to represent one square inch.
inch and
inch of
exposed
were