Fabrication of radiation detector using compound-semiconductor (PbI2, TlBr)

Abstract

The radiation detectors were fabricated from the PbI2 and TlBr crystals. The PbI2 crystals were grown by four different methods. For the PbI2 detectors fabricated from the samples grown by the ordinary Bridgman method, the alpha-peak was not observed. In the detector fabricated from the samples grown by Bridgman method after the 20 pass zone refining, the alpha-peak with an energy resolution of about 759 keV (FWHM (the Full Width at the Half Maximum)) was clearly observed at an applied detector bias of 20 V. However, the photopeak for gamma-rays was not observed. The detector fabricated from samples grown by 60 pass zone melting method successfully yielded a photopeak for Am-241 gamma-rays (59.5 keV). In the case of the TlBr crystal, some trace of response for alpha-rays was observed, but the peak in the pulse-height spectrum was not yet observed.

PbI2とTlBrの結晶から放射線検出器を作った。PbI2結晶は異なった4方法により成長させた。通常のブリッジマン法により成長させた結晶から作ったPbI2検出器では、αピークは観測されなかった。20回の帯溶融の後に、ブリッジマン法で成長させた試料で作った検出器では、20Vのバイアス電圧において、約759keV(FWHM)のエネルギー分解能でαピークが明瞭に観測された。しかしγ線のフォトピークは観測されなかった。60回の帯溶融の後に結晶成長させた試料で作った検出器では、Am-214のγ線(59.5keV)のフォトピークを得ることに成功した。TlBr結晶の場合は、α線への応答の痕跡は観測されたが、パルス波高スペクトル中のピークはまだ観測されていない。