Composite detector for mixed radiations based on CsI(Tl) and dispersions of small ZnSe(Te) crystals

A new large area detector of high-energy X-ray and beta-radiation has been designed and studied. A composite material based on small-crystalline ZnSe(Te) was applied onto the wide surface of a light guide. An experimental specimen has been prepared, which showed beta-sensitivity C-beta = 5.5 cm(2). The spectrograms of a Sr-90 + Y-90 beta-source obtained with the specimen under study make it possible to evaluate the age of the source by the ratio of low- and high-energy regions of the spectrum. The combined detector (CD) comprises a single crystalline plate of ZnSe(Te) placed onto the output window of a scintillating transparent light guide made of CsI(TI) in the shape of a truncated pyramid. The CsI(TI) light guide is used to create an additional channel for detection of gamma-radiation, as well as for protecting the photodiode from the penetrating radiation. It is shown that introduction of the light guide does not worsen the energy resolution characteristics of ZnSe(Te). Separate detection of alpha- and gamma-radiation has been achieved under simultaneous excitation by Pu-239 (ZnSe(Te), R-alpha = 6%) and Am-241 (CsI(TI), R-gamma = 20%). The use of selective optical filters allows separation of the peaks of total absorption (p.t.a.) in the case of their superposition. (c) 2005 Elsevier B.V. All rights reserved.