Operational characteristics of a high purity germanium photon spectrometer cooled by a closed-cycle cryogenic refrigerator

Experience with several (commercially available) miniature closed-cycle refrigerators used to cool a high purity germanium photon detector is reported. While maintaining good resolution, closed-cycle cooling has resulted in a versatile photon spectrometer with long storage times, variable length run times, and freedom from the need for a liquid nitrogen supply. The demonstrated resolution and background levels indicate the concept to be especially useful for field measurements in problems of general radioisotope detection and in some applications of on-line x-ray fluorescence.