A portable or permanently installed radiation detection and spectroscopy instrument, that detects neutron, beta and alpha particles by the production of electron-hole pairs along the path of the charged particle in a semiconductor. It typically consists of a semiconductor diode, using an ohmic contact (a non rectifying electrode) and a detection circuit to measure the resulting current, electronics, and read out sub-system. The semiconductor acts like a solid ionization chamber. It has fast timing characteristics but is susceptible to performance degradation from radiation induced damage and may measure doses during radiation therapy treatments.