Experience in the Use of an Anticoincidence Shielded Ge(Li) Ganma-Ray Spectrometer for Low Level Environmental Radionuclide Analysis

An evaluation of a low level, high resolution anticoincidence shielded Ge(Li) spectrometer, constructed over five years ago, has been made. The evaluation was based upon results obtained in assaying a variety of biological and environmental samples, each contained in a 200 cm3 aluminum can. The spectrometer used an 18 cm3 planar type Ge(Li) detector constructed in our Laboratory. An example of the very high sensitivity possible with the spectrometer was in the assaying for 137Cs in a 296 gram soil sample which was determined to have a concentration of 0.027 pCi of 137Cs per gram of soil. Description of the spectrometer, methods used in data analysis and results of counting low level samples are given.