A device, more correctly described as a crystal detector, that detects ionizing radiations of all types and is adaptable to measuring neutrons. The sensitive element is a single crystal with a dc resistance normally higher than 10¹² ohms. The crystals are small and are cut or grown to volumes ranging from less than 1 mm³ (6 × 10^-5 in.³) to approximately 200 mm³ (1.2 × 10^-2 in.³).