Gamma Ray Spectroscopy

Simultaneous analysis of multiple specific radionuclides can be done using gamma ray spectroscopy (Heath 1974). This method is applicable to the analysis of gamma-emitting radionuclides with gamma energies ranging from 80 keV to approximately 2000 keV. The technique minimizes the sample preparation required to do radio-chemical analysis. Using a Nal detector, it is possible to routinely analyze four to eight gamma-emitting radio-nuclides. Personal computer-based, high-resolution intrinsic germanium detector systems are now used almost exclusively in gamma ray spectroscopy. These systems can analyze an almost unlimited number of radionu-clides, and are especially suited for low-level analysis of environmental samples. A comparison of the superior resolution of an intrinsic germanium detector is shown in Figure 11.24.3. The most frequently used photo-energy peaks for common radionuclides are shown in Table 11.24.1. Liquid and solid samples can be placed directly in a Marineli beaker for analysis. An efficiency calibration is required for quantitative analysis. The result of this calibration is an efficiency versus energy curve (Figure 11.24.4).

FIG. 11.24.2 De-emanation assembly.
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