scattering, and atsorption do not affect the detector resnonse or gamna spectrum seen by the detector. Since the letter condition is never fully satisfied, the calculated curve always differs from the experimental one. Table 5.1 tahulates the slopes of the theoretical decay curves considered. The experimental beta decay curve for Shot 4 (Fig. 5.1) and the experimental gamma ionization decay curve (Fig. 5.2) for Shot 1 are presented for compericon. The two theoreticel beta decay curves are in very close agreement and each arree well with the experimental beta decay curve. The experimental camsia ionization decay curve for Shot 1 and the cal- culated gamma (Mev/min) decay curve (Fig. 5.2) ere not in food agreement 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 Decey Data Slope of Decay Curve over Period Indicated| (hr after ABD) l= 3}1=- 5/3 - 4815 - 96 24 = 1440 96 - 672 Calculated gamma ionization decay -- 1.37 Shot 1 (Mev/min) 1.08 Calculated beta | decey -- Shot 1 (d/m)/ 1.42 0.83 | Calculated beta decay -- Mike Shot, 0.865 Ivy (d/m) LeAL 1.33 | | 1.40 | 1.37 a Type of Decay | Fieure 5.3 is a composite gamma ionization decay curve constructed from all aveilable field data; it has been used in this renort for conversion of all field data taken with an AN/PDR-T1B, AN/®SDR/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 2.58 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-intensity recorder curve with field survey readings was assumed to hold between 0 + 2 hr and O + 2 days. Therefore, for the time interval (0 + 3 hr to 0 + 20 days) the time~ intensity 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 arrivi:~+: the compensated curve would then have a slope steeper than the experime..-1 decay curve. For this interval (0 + 1 hr to O * 3 hr) the calculateu cemma decay curve was used in te construction of this composite decay curve. 53