Solving Eq. 5.4 with the data from Table 5.5 for shelves 1, 2, and 3

gave the values of the constants in Bq. 5.2.

Hence,

R° a R + 2,920 x 1076R2 + 1,388 x 10710R3.6,733 = 107164

(5.5)

Equation 5.5 may be expressed as,

(5.6)

RoR a lt+y

in which y/R = 2.820 x 10-64 1.388 x 107)R-6.738 x 10°14?

(5.7)

These equations give an effective dead time of 200 ;,sec at about 4000 c/a,

The value of y for each observed sample and background count was read
from a plot of y against R. From+ 1.5 days, + 5 days, the sample was
observed on a gas-flow counter at the site and from + 9 days it was

counted at USNRDL on other gas-flow counters, The ionization and beta
check well from about 0.4 to 10 days; at earlier times the ionisation
decay was somewhat faster.
Calculated beta decay curves for Shots 1 and 4 are plotted
in Fig. 5.4. The decay of the induced activities for Shot 4 are included.

The calculations were based on capture to fission ratiosd//

and on the fission product d/m for 10,000 fissions at sero time,
The
experimental beta decay for Shot 4 are superimposed on the plots by
normalizing the 10-day values. Agreement between the observed and calculated curves is fair. The induced activities cease to effect the zroas

decay at + 60 days.

The calculated decay curves exhibit some differences

in the mode of decay between

the radicactivities produced by Shots 1

and 2 for times less than + 60 days. The observed curves are all somewhat steeper at + 60 days and longer. The gamma decay of samples from
Shots 2 and 4 at times shorter than + 10 days are different. Unfortunate

.

only single samples were available for the early time decay for those two .

cases; and, further, the decays were observed on counters having different;
spectral responses,

Hence there is no basis for determining the real

significance, if any, of the differences,

The ionization and gamma cout,

<

decay could not be expected to agree with the calculated curves as closely

as the beta decay; however, their divergence generally was not great for ©
short intervals of time.

51.3 Spectrometer
Since the gamma analyser was converted from an alpha analyser efteqD
Shot 1, it was not available for early measurements on fallout samples frp
that shot.

Gamma spectra were taken of gross decay samples from Shots

sy.

2 to 4 at various tines after detonation, The results are sumerised iC:
;
Tables 5.6 through 5.9. In these tables the heights of the various
Z
™
0.1
nearest
peaks
energy
the
for
one
of
value
a
are shown relative to
Since a small Ral crystal was used, the spectra were linited to :
the lower energy region and the peak at about 0.5 Mev was undoubtedly
contributed to by annihilation radiation from gammas of higher energy

than 1 Mev,

However, the data were used minly to compare the general
112

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