Measurements of response function of a cylindrical Ge detector to a collimated gamma-ray beam

The response function of a cylindrical Ge detector for collimated gamma-ray beam was measured by changing the incident position perpendicular to the upper plane of the Ge cylindrical crystal. The position-dependent response function was also simulated by the EGS4 Monte Carlo code. Both the simulated response function and the position-dependent peak efficiency was compared with the measured results and showed good agreement in the energy range from 898 keV to 1.836 MeV. From measured and simulated results, a maximum peak efficiency of the Ge detector to the collimated gamma-rays was obtained at the position of 12 mm from the center of the incident upper plane of Ge crystal. It is also obtained in the measurements at 5.969 MeV and 9.945 MeV laser compton scattered (LCS) photons. (J.P.N.)