低バックグラウンドGe検出器の遮蔽性能の改善  [in Japanese] Background Reduction of Low Level Gamma-Ray Spectrometer  [in Japanese]

A new low-background shielding was installed for a Ge detector. Background gamma-ray spectrum was measured and compared with that of old shielding to investigate how improved the background counting rate. Additional improvements for the new shielding was installed to reduce background counting rate. It has been shown that shielding of the neck part of Ge detector cryostat and concrete floor are effective to reduce background contribution. The reduction factor of ^<40>K 1461 keV gamma-ray was much improved from 51 of old shield to 4290 of new shield.

A new low-background shielding was installed for a Ge detector. Background gamma-ray spectrum was measured and compared with that of old shielding to investigate how improved the background counting rate. Additional improvements for the new shielding was installed to reduce background counting rate. It has been shown that shielding of the neck part of Ge detector cryostat and concrete floor are effective to reduce background contribution. The reduction factor of ^<40>K 1461 keV gamma-ray was much improved from 51 of old shield to 4290 of new shield.