Ionization energy in an HPGe semiconductor detector

Abstract We report measurements of the relative pulse heights produced simultaneously by alpha particles with energies in the range 3.2–5.8 MeV and gamma rays in an hyperpure Ge detector at T = 80 K. From these data, we conclude that the mean energy to create electron-hole pairs is smaller for α's than for γ's i.e. ϵ α 0 contrary to earlier conclusions. Specifically, ϵ α / ϵ 0 = 0.9914 ± 0.0010 at E α = 5486 keV. The deviation in the ratio ϵ α /ϵ 0 from unity increases with decreasing α energy.