Background components of Ge detectors in Ogoya underground laboratory.
Ogoya underground laboratory, (OUL; 270 m water equivalent), has 5 well, 4 planar, and 1 coaxial-type ultra-low background Ge detectors with passive shield of old lead. An anticoincidence system with a plastic scintillator (PS) has been tested to reduce cosmic-ray-induced background. Energy spectra of PSs, coincidence counting rate, and angular distribution of cosmic rays were studied. Based on this study, we propose a new index of Ge surface area-normalized background counting rate (d(-1) cm(-2)) to compare shielding efficiency between different types of Ge detectors.
Hamajima
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Y
LLRL, Kanazawa University, Tatsunokuchi 9231224, Japan. hama@cacheibm.s.kanazawa-u.ac.jp
Komura
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K