scattering, and atsorption do not affect the detector resnonse or gamna
spectrum seen by the detector. Since the latter condition is never fullr
satisfied, the calculated curve always differs from the experimental one.
Table 5.1 tahulates the slopes of the theoretical decay curves considered.
The exoerimental beta decay curve for Shot 4 (Fie. 5.1) and the experi-
mental gamma ionization decay curve (Fir. 5.2) for Shot 1 are presented
for compericon.
The two theoreticel beta decay curves are in very close
apreement and each arree well with the experimental beta decay curve.
Tha experimental carma ionization decay curve for Shot 1 and the cal-
culated gamma (Mev/min) decay curve (Fig. 5.2) ere not in food arreement
from 5 to 100 hr after detonation. This lack of acreenent may te due to
the nature of the response of the ionization instrument or to other factors.
TABLE 5.1 - Theoretical Decay Data
Type of Decay
Slone of Decay Curve over Period Indicated
(hr after ABD)
L-3/1-+5)3 - 48/5 - 96:2 - 1440
Calculated ramma
ionization decay --
1.37
Shot 1 (Mev/min)
1.08
Calculated beta
decey -- Shot 1 (d/m)i1.42
Calculated beta
decay -- Mike Shot,
Ivy (d/m)
0.83
|
{96 - 672
|
1.33
i
1.40
t
{1.44
0.265 |
|
1.37
ab
Firure 5.3 is a composite pamma ionization decay curve constructed from all avcilable field data; it has been used in this renort
for conversion of ell field data taken with an AN/PDR-T1B, AN/DR/39,
or the gemma ionization time-intensity recorders as well as for conversion of the 47 gamma ionization chamber laboratory data, Comparison
of How Island Task Force Rad Safe measurements and the Project 2.59
gamma time-intensity measurements shows very close agreement from 0 + 2
to 0 + 20 days after Shot 1 (Table 5.2).
This agreement of the time-intersity recorder curve with field
survey readings was assumed to hold between O + 2 hr and O + 2 days.
Therefore, for the time interval (0 + 3 hr to 0 + 20 days) the timeintensity recorder data were used to construct the composite curve
(Fig. 5.3). However, for the interval from 0 + 1 hr to O + 3 hr the
gamma tine-intensity recorder must be compensated for fallout that was
still arriv.--+: the compensated curve would then have a slope steener
than the experime...-1 decay curve. For this interval (0 + 1 hr to
0 * 3 hr) the calculateu wtcemma decay curve was used in tlie construction
of this composite decay curve.
53