Full-energy peak efficiency calibration of a HPGe detector using radioactive sphere source

摘要

Direct mathematical expressions to calculate the absolute photopeak efficiency for the NIST HPGe detector in case of a gas sphere sources filled with noble gases (85)~Kr and (133)~Xe have been derived. In addition, the attenuation of the photons by the source container, the window and the end cap materials is also presented in a simple straightforward mathematical expression. The photopeak efficiency values as a function of the photon energies are shown in Figure 2. As seen from Figure 2, increasing the window material atomic number is nearly insignificant in the energy range higher than 110 keV which is the inversion point of the efficiency-energy curve, whereas, it decreases the efficiency values slightly in the range less than the inversion point.