Gallium Arsenide for γ-Ray Spectroscopy

CRYSTAL conduction counters offer an improvement in energy resolution over ionization chambers or scintillation counters for spectroscopy of nuclear particles. Semiconductor counters which employ a p–n junction are useful only for heavy charged particles of moderate energy. For energetic charged particles or γ-rays with ranges exceeding 1 mm. of silicon a crystal with efficient charge collection throughout its bulk is required. Most crystals of sufficiently high resistivity contain so many electron traps that collection of the ionization current is inefficient, and only diamond has previously been found to count single γ-ray events. The usefulness of diamond as a crystal counter is restricted.