A large volume, multi-element Ge(Li) spectrometer

Abstract

To make use of the good energy resolution of Ge(Li) spectrometers of r-ray energies of several MeV, the sensitive volume must be increased to beyond 100 cm3. This volume is generally only attainable by operating several smaller spectrometers in parallel. Three coaxial Ge(Li) detectors were fabricated, assembled in a cryostat and operated in parallel. The spectral performance was relative efficiency of this multi-element spectrometer were investigated for r-rays of energies between 1 and 10 MeV. High energy r-rays (5-10 MeV) were obtained by thermalising neutrons from a Pu-Be source and then absorbing them in materials with high cross sections for radiative capture. The experience gained is summarised and alterations to future multi-element spectrometers are proposed.