A diamond radiation detector

Type-IIb diamonds are partially compensated p-type semiconductors at room temperature. Radiation damage makes such diamonds highly insulating. This effect can be exploited to make a fast radiation detector which is sensitive both to light and charged particles. This is done by confining the radiation damage to a narrow band within the crystal. The decay time is less than 3×10−10 s after illumination with photons of energy 3.68 eV (337 nm). The fact that ’’counting diamonds’’ can now be manufactured from the relatively abundant type-IIb diamonds, both natural and synthetic, will be of some interest, since natural counting diamonds are very rare.