Investigating effects of coaxial HPGe detector structure on the measurement of LCS -ray beam

Omer, M.  ; Shizuma, Toshiyuki*; Koizumi, Mitsuo ; Hajima, Ryoichi*; Zen, H.*; Taira, Yoshitaka*

Coaxial high-purity germanium detectors are essential components of high-resolution -ray spectrometers. Indeed, these detectors come in various dimensions with different internal structures. Particularly when the measured -rays are in the form of a directed beam, the detector internal structure may affect the measured -ray spectra significantly. Here we investigate the effect of the internal structure of two different coaxial HPGe detectors using 5.54 MeV -rays generated by laser Compton scattering at the UVSOR III facility. The -ray beam hit the detectors in two configurations, axial and nonaxial. We found that the nonaxial configuration provides higher efficiency and lower background than the axial configuration, which was confirmed using Monte Carlo simulations. Our results provide improvements in the measurement of -ray beams. This work is a contribution of the Japan Atomic Energy Agency (JAEA) to the International Atomic Energy Agency (IAEA) under the agreement of the coordinated research program (CRP), J02015 (Facilitation of Safe and Secure Trade Using Nuclear Detection Technology - Detection of RN and Other Contraband).