THE GENERATION OF THE RESPONSE MATRIX OF HEMISPHERICAL CDTE DETECTORS

Hemispherical CdTe detectors were chosen as part of a portable in situ gamma spectrometer to investigate the angular and spectral distribution in gamma- and X-ray fields at work places. The reason for this choice was that the low weight and small size of the spectrometer to be carried by the person in the radiation field are more important than an excellent energy resolution. This paper deals with the generation of the response matrix for the CdTe detectors and with the unfolding procedure. The response matrix of the CdTe detectors was determined experimentally. For this purpose the pulse-height spectra of 11 isotopes emitting monoenergetic gamma radiation were measured. The resulting spectra represent the response of the CdTe detectors to monoenergetic photons of the respective energy. These spectra were approximated by a model function which makes use of 19 energy-dependent parameters. The interpolation of these parameters with respect to the energy and the calculation of the corresponding pulse-height spectra yields the response matrix. The capability of this method is demonstrated by examples.