Some new scintillator-photodiode detectors for high energy charged particles

Abstract

The development of a useful scintillator-photodiode detector suitable for the detection of high energy charged particles is described. The detector combines the convenient features of solid state devices without suffering from the lack of stopping power associated with pure semiconductor devices. The energy resolution approaches that obtainable with a scintillator-photo-multiplier detector under similar conditions. A careful analysis of the physical processes involved in the detection of light by a photodiode is followed by a description of the silicon surface barrier photodiodes made by the author. When used in conjunction with CsI(Tl) scintillators the author's photodiodes made from n-types silicon gave resolutions of 15.7% fwhm with 5.48 MeV particles and 4.2% fwhm with 50 MeV protons. Photodiodes made from p-type silicon are described which give similar performance but which are potted in epoxy resin and to which scintillators may be optically coupled in the usual way without any degradation of the diodes' electrical properties. Attention is drawn to the practical advantages of the scintillator-photodiode detector for high energy particle detection and the potential for future development examined.