Study of Summing peak effect for High Purity Germanium Detector

It concludes data both from experiment and simulation,at different distances.The measurement of low-level radioactivity using HPGe detectors is of utmost importance in applications such as environmental background radiation, material screening, and the study of rare decays. The dead layer, dead zone, aluminum shell thickness, and diameter of the Ge-crystal are the most influential contributors affecting the detector's performance, hence the precise modeling of the physical condition of the detector is highly desirable. In the present study, the GEANT4 simulation framework with optimized detector geometry adequately replicated the experimentally recorded spectrum. These detector simulations explore the idea of realizing a dead zone (an inactive volume) at the backend of the N-type coaxial Ge-crystal. Using multi-gamma sources, the effect of true coincidence summing (TCS) on the full energy peak (FEP) efficiency calibration of the HPGe detector has also been investigated as a function of sample-to-detector distance. A striking resemblance between the simulated and experimental efficiencies as well as the simulated and analytically calculated summing coincidence correction coefficients has been achieved. At a short distance between the source and detector, calculating the correction factors with a strong source in the experiment poses challenges due to the significant deadtime and pile-up effects of the detection system. The described methodology can efficiently determine the summing peak probability at a short sample-to-detector distance.