SIMSPEC-G: a simple code for the simulation of HPGe detectors for gamma rays up to 1 MeV

Abstract

A new program called SIMSPEC-G has been developed to simulate the interaction of gamma-rays of energies upto 1 MeV with different materials. In this work, 3 different geometries of high purity Ge (HPGe) detectors have been studied: single crystal HPGe, segmented single crystal HPGe and clover geometry composed of four HPGe crystals in clover-leaf arrangement. Contributions of different processes to peak formation have also been examined. The simulated spectrum, for a single crystal of clover, and for 662 keV gamma-ray (from 137Cs source) has been compared with experimentally obtained spectrum. The addback factor (gain in full energy peak efficiency due to the addition of the energies of the Compton scattered gamma rays in more than one crystal of a clover HPGe detector) and the hit pattern for a range of gamma-ray energies from the experiment have been excellently reproduced by the simulation leading to its validation. The fraction of total events in which highest or full energy is deposited in the first hit crystal is estimated and the use of this idea to improve angular resolution of a Clover detector has been explored.