IgrTr? 8Cic where IgiTR > the radiation intensity (r/hr) due to deposited activity, Cie is the gamma activity (C/min) of the IC tray determined on Shelf 5 of End-Window Gamma Counter 2 and corrected to time of deposition, and 3 is a constant empirically determined to be 0.71 x 1077, lf this data had been required for an interpretation of the Hardtack data, energy corrections would have been required and it would have been necesSary to repeat the preliminary experiment with greater precision. It is used in this report to convert IC tray counis at 22 days to a std- GITR response for the sole purpose of establishing the approximate magnitude of the maximum dose rate due to deposited radioactivity. Since an analysis of the material deposited from the base surge after either shot (Reference 105) showed considerable enrichment in Ba!4°.~na'? and since the relative importance of these radionuclides is greatest at about 22 days (Reference 126), the energy spectrum of the deposited material at this time most closely approximmtes that of the La‘slurry used to determine the conversion factor. A comparison of the experimental with the theoretical decrease in relative intensity with height above the coracle deck is given in Figure C.18. The empirical curve agrees with the theoretical curve within the limits of experimental error; the differences in shape are probably due to differences in energy. These curves were useful in converting survey meter dose rates into maximum probable std-GITR dose rates. C.6 UNDERWATER RESPONSE OF STD-GITR The std-GITR detector in an underwater casing (Section 2.2.2) was immersed into a 6-foot diameter tank containing known concentrations of Cs’, La!?, and Co" in sea water. The recorded GITR dose rate above 20 mr/hr is directly proportional to concentrations in the sea water. The empirically determined conversion factor from the UW-GITR dose rate in r/hr to concentration in photons/sec per liter is 3.5 x 10’, Assuming no fractionation and neglecting induced activity, concentrations so expressed may be converted to fissions/m1 with an estimated accuracy of «20 percent, using the average photon energies summarized in Section A.1. The GITR detector in its underwater casing is calculated to have a total response of approximately 37 steradians; this response agrees with the experimentally determined underwater response to within 10 percent. Since the source is distributed entirely around the detector, the underwater response is considered to be the most accurate determination of total response. A complete description of these underwater measurements may be found in Reference 127. TABLE C.1 Energy Mev RELATIVE ENERGY RESPONSE FOR END-WINDOW GAMMA COUNTER 2 FOR A POINT SOURCE ON SHELF 5 Relative Response Energy Relative Response pet Mev pet 0.025 0.03 0.04 0.05 0.0528 0.2896 0.680 0.926 0.40 0.50 0.60 0.8 0.487 0.416 0.376 0.327 0.06 1.0425 1.0 0.296 0.30 0.612 0.08 0.10 0.15 0.20 1.1175 1.1542 1.055 0.886 1.5 2.0 3.0 4.0 0.249 0.226 0.207 0.200 368 Zs