Ionization energy for charged particles in Ge

The response of a hyperpure Ge detector (volume ∼0.7 cm3) to ionizing radiation has been studied with regard to the radiation ionization energy ratio, var-epsilon ion/var-epsilon 0, using radioactive (α,γ) sources and accelerated ion beams (1H,4He). These data provide evidence that var-epsilon ion is not identically equal to var-epsilon 0 for low-energy (e.g., few MeV) charged particles, in qualitative accord with data for Si detectors. The apparent thickness of the ion-implanted entrance window of the detector exhibits a marked dependence on temperature in the region 80--183 K. As well, channeling effects have been observed which can be attributed to residual crystalline structure in this inactive layer