Monte Carlo modelling of gamma-ray stopping efficiencies of Geiger-Müller counters

A detailed study of the intrinsic stopping efficiency mechanisms of low energy gamma-rays (59.5 keV) in a Geiger-Müller counter is presented. MCNP5 and PENELOPE 2006 simulations have been carried out and the simulation results have been benchmarked with experimentally obtained stopping efficiencies. The results show that the inner wall interactions are critical for the gamma-ray stopping efficiencies.