Developing a New Default Characterization Method for In Situ Gamma-Ray Spectrometry

L. Tkavadze; R. Dunker; R.R. Brey; and T.F. Gesell (Idaho State University - Dept. of Physics/Health Physics Program)

Default characterization methodologies for High Purity Germanium Detector Systems (HPGe) used during in situ gamma spectroscopy are preferred when empirical characterization is not be performed due to technical or financial limitations. The main purposes of this study were to develop a new default methodology for estimating characterization parameters, to expand these values, and to compare them to the existing tables. Such were originally developed by the D.O.E. Environmental Measurement Laboratory (EML), using their empirical characterization method. Response functions are determined from these tables using a detector’s relative efficiency and crystal dimensions of a HPGe. Accuracy of the results obtained by this method is between 85 and 90 percent. The empirical characterization method used in our study was the Rotating Arc Method developed by R. Reiman. The study was completed in the Environmental Monitoring Laboratory at Idaho State University. Nine HPGe detectors with great variety have been characterized and a simple default methodology for estimating characterization parameters has been developed. The estimates have been compared against the empirical characterization results published by EML. Based on our results, one may estimate the response functions for detectors with relative efficiencies between 23 and 78 percent and crystal length-diameter ratios between 0.90 and 1.36.

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