[2M10-13] Photon Detection 1

[2M12] Evaluating Coaxial HPGe Detector Efficiency in Beam Geometry Using LCS gamma-ray Source

*Mohamed Omer¹, Toshiyuki Shizuma^1,2, Ryoichi Hajima^1,2, Mitsuo Koizumi¹, Yoshitaka Taira³ (1. Japan Atomic Energy Agency, 2. National Institutes for Quantum Science and Technology, 3. National Institutes of Natural Sciences)

Keywords:coaxial HPGe detector, detector efficiency, laser Compton scattering, Monte Carlo simulation

High-resolution gamma-ray spectroscopy involving beam geometry may be measured with higher efficiency if gamma-ray beam hits out of the axis of the coaxial HPGe detector. Hitting off-axis makes gamma-rays avoid travelling through the contact hole, which is an inactive axial portion of the detector. We performed Monte Carlo simulations to study the effects of contact hole dimensions and off-axis distance on the coaxial HPGe detector efficiency. The simulation considered gamma-ray energy up to 10 MeV. In general, the simulation results reveal that the off-axis efficiency is higher than on-axis efficiency for a wide range of gamma-ray energies and beams sizes. Our simulations results are validated by experimental measurements of gamma-ray beams generated from laser Compton scattering at UVSOR III facility