50 20 10 N _—_ 50 & 2 {% "1S 20 oO \ a \ ~~” G o 1.0 N LL. i. Li 0.6 N 0.2 0.1 10 20 50 100 200 500 1000 ENERGY (keV) FIGURE 3-6. A TYPICAL DETECTOR EFFICIENCY VERSUS ENERGY CURVE FOR THE HPGe PLANAR DETECTORS USED AT ENEWETAK. Conversion factors, in units of pCi/g per cps, can be obtained for these radionuclides, as well as any others which might be present in detectable quantities, by using Equation (8) in Section 3.2.5 with the appropriate input parameters. Figure 3-6 shows a typical detector efficiency (A,) curve for the HPGe planar detectors which were used at Enewetak. Angular response data, R (6), were also obtained for a number of gamma ray energies. Figure 3-7 shows the results for 662 keV gamma rays from 137Cs with and without the collimator. Although the collimator does have a significant effect on the angular response, it was not thick enough to provide complete cutoff at the higher energies as it did for the 60 keV gamma rays from 24lam (see Figure 3-3). 100