The combined correction factor was used only in the analysis of the initial-gamma-exposure data in Table 3,16. Uncorrected exposure values are listed in the individual shot tables in Chapter 3. 2.3,2 Residual-Exposure Calibration. In order to evaluate the initial-gamma exposure, it was often necessary to estimate the residual-gamma exposure. Some of the dosimeters associated with the quartz-fiber device and the mechanical dropping mechanism yielded measurements of residual-gammaradiation. Over the limited areas of interest (500 feet or less) the fallout pattern was generally continuous and exposures did not vary greatly, hence it was possible to estimate the exposures at stations where no specific data were available. These estimates were consistent both with calculations based on measurements of residual-gamma intensity made at the time of station instrument recovery and with integrated rate versus time measurements made by Project 2.2. Stations located on the reef and in the tidal wash area were evaluated separately, since the residual exposure in these areas could have been reduced by a factor of ten, depending on the water-land geometry and tidal wash. In cases where the estimated residual exposure exceeded the resultant initial exposure, an additional uncertainty factor had to be added to the normal accuracy factor. It was desirable to correct the residual-exposure values obtained inside the station to those that would exist outside the station if the dosimeters were unshielded. To determine this correction factor, dosimeters were wired flush to the outside of some stations where they would be exTABLE 2.7 . RESIDUAL-GAMMA-EXPOSURE CORRECTION FACTORS . . Film - Quartz Station Attenuation Instrument Attenuation Combined Quartz Fiber 1.12 1.12 1.25 1.15 1.44 1.85 1.24 2.30 1.25 2.88 2.00 1.36 2.72 1.25 3.40 213 1.48 1.12 1.66 1.20 2.00 113 1.36 1.12 1.52 1.20 1.83 Station Series 210 i Fiber . Normalization Combined Film 210' without quartz 211 fiber rate 212 device 210! with quartz 211 fiber rate 212 device pected to survive the blast and thermaleffects of the event. In some cases, four instruments uniformly spaced about an 8-inch (outside diameter) pipe were used. The variation of exposure in each instrument set was due primarily to the land-water geometry. Since the station still shielded the instruments from 4 7 radiation, the results obtained did not directly yield the correction factor. Therefore, attenuation factors were calculated based on station construction assuming 700 kev as the effective energy of the residual-gammaradiation (Table 2.7). These were consistent with experimental results. Figures 2.7 through 2.11 show the energy response of Dupont Emulsions 502, 510, and 606 in NBS holders, and of quartz-fiber dosimeters and the AN/PDR-39 relative to Co, Since the response of the quartz-fiber dosimeter was found to be most desirable during previous operations (Reference 4), experimental factors were evaluated to adjust the film readings to quartz-fiber equivalence. These factors were 1.15 for film in aluminum containers and 1.25 for film in 8inch steel-pipe stations (Table 2.7). The factors in Table 2.7 were considered accurate to within 20 percent because of variations in thickness of blast shielding. Residual-exposure data that 24