and numberof fissions as determined by Mo"content, and no arbitrary normalization has been employed to match theory and experiment. Thus, the curves in Figure 3.39, for instance, rep. resent the best available estimates of the SC dose rate produced by 10 fissions/ft? of the various mixtures. The Mo®® content of each of the samples represented is identical, namely the number corresponding to 10‘ fissions at a yield of 6.1 percent. The curves are displaced vertically from one another solely because of the fractionation of the other fission products with respect to Mo®®, and the contributions of various kinds and amounts of induced products. It may be seen that the computed and observed doghouse-counter decay rates are in fairly good agreementover the time period for which data could be obtained. The beta-decay curves for Shots Flathead and Navajo, initiated on the YAG 40, suggest that the computed gamma and ionization curves, for those events at least, are reasonably correct as early as 10 to 15 hours after detonation. The ionization results may not be checked directly against experiment; it was primarily for this reason that the other effects of the proposed compositions were computed for laboratory instruments. If reasonable agreement can be obtained for different types of laboratory detectorg, then the inference is that discrepancies between computed and measured ionization rates in the field are due to factors other than source composition and ground-surface fission concentration. The cleared area surrounding Station F at How Island (Figure 2.8) offers the closest approximation to the standard conditions for which the calculations were made, and Shot Zuni was the only event from which sufficient fallout was obtained at this station to warrant making a comparison. With the calculated dose rates based on the average buried-tray value of 2.08 +0.22 x 10" fissions/ft? (Table B.27) and the measured rates from Table B.28, (plotted in Figure B.7), the observed/calculated ratio varies from 0.45 at 11.2 hours to 0.66 from 100 to 200 hours, fall- ing to an average of 0.56 between 370 and 1,000 hours. Although detailed reconciliation of theory and experiment is beyond the scope of this report, some of the factors operating to lower the ra- tio from an ideal value of unity were: (1) the cleared area was actually somewhat less than infinite in extent, averaging ~ 120 feet in radius, with the bulldozed sand and brush ringing the area in a horseshoe-shaped embankment some7 feet high; (2) the plane was not mathematically smooth; and (3) the survey instruments used indicate less than the true ionization rate, i.e., the integrated response factor, including an operator, is lower than that obtained for Co®in the calibrating direction. It is estimated that, for average energies from 0.15 Mev to 1.2 Mev, a cleared radius of 120 feet provides from ~ 0.80 to ~ 0.70 of an infinite field (Reference 46). The Cutie Pie survey meter response, similar to the T1B between 100 kev and 1 Mev, averages about 0.85 (Reference 17). These two factors alone, then, could depress the observed/calculated ratio to ~ 0.64. 60