Properties of the two-layer composite detectors and x-ray energy dispersive spectrometers, based on the detectors

The mathematical model for the two-layer Si-Ge, Si-AsGa, Si-CdTe X-ray energy dispersive detectors is proposed, based on X-ray radiation and photon transport in detector. Also the mathematical model of the energy dispersive spectrometer, based on the detector, is considered. Using Monte-Carlo method, the probabilities of the photon registration in a different parts of the detector response function are calculated. It is shown that using the Si detector as the first layer of the detector, Ge, AsGa or CdTe detector as the second layer, and time anticoincidence scheme it is possible to design the detector with some adventures: with reduction of photo escape peak of the second detector and with high-energy efficiency the same as the second detector. It is shown that in some cases, if the two-layer detector is used, signal to background ration is increased.