Long term variation on characteristics of germanium detectors

Abstract

Long term variation of characteristics of three germanium semiconductor detectors (Ge detector) were investigated. These detectors were two coaxial type lithium drifted Ge detectors with relative efficiency, 10.2 and 13.6 percent, respectively, and a coaxial type high purity Ge detector with its value 40.5 percent. Eight standard gamma ray calibration sources were used, and relative efficiency, output pulse width, peak to Compton ratio and liquid nitrogen consumption were checked for more than ten years. As a result, main causes of deterioration of Ge detector were found.

3個のゲルマニウム半導体検出器の特性変化を長期にわたって調べた。それらは、相対効率がそれぞれ10.2%と13.6%の同軸型リチウムドリフトゲルマニウム検出器、およびその値が、40.5%の同軸型高純度ゲルマニウム検出器である。較正線源として8種の標準γ線源を用い、10年以上の期間、液体窒素消費量、相対効率、出力パルス幅、ピーク対コンプトン比を調査した。その結果、性能低下の主な原因が明らかになった。