I simulated HPGe detector including the detector housing and the detector material. The simulation geometry is very simple, first, the source is an isotropic and monoenergetic (0.662MeV). The Germanium detector is ~3 cm away from the source. I want to get the spectrum of the detector. I tried by finding the energy deposition by the primary particle but I got very sharp peak at 0.662 MeV. So I changed the measured quantities in the code, I just recorded the number of electron/hole pairs created in the detector by counting the eIoni processes (as shown in Figure 1), I got low energy resolution (7%) compared to experimental spectrum. Next, I measured the total energy deposited by the ionized electrons (eIoni process) (Figure 2) but I got high resolution (0.06%). Any ideas what I should count to find the correct spectrum in such a simulation? examples other than Geant4 examples would be appreciated.
Gamma spectrum.pdf (177.0 KB)