Thermal Neutron Dosimetry with Cadmium Telluride Detectors

Abstract

Abstract Cadmium telluride, a semiconductor compound with high Z is presently used at room temperature as a gamma ray detector. We have used this material to detect thermal neutrons by making use of the very high cross section of 113Cd to absorb thermal neutrons and emit gamma rays. Two CdTe detectors were exposed to a known thermal neutron beam at the CRN reactor, in order to analyse the performance of this device and a Monte Carlo code was developed to determine the expected response spectrum. For the two devices considered here under a series of experimental conditions, satisfactory agreement was observed between calculations and experimental data. Some of the 113Cd(n,?) radiative capture lines were identified by calibrating the detector with 57Co source. Since the atomic density of CdTe is much higher than in gas detectors, the efficiency under a small volume is very high, even if the total volume is presently limited to 10 x 10 x 2 mm3. In using CdTe as a thermal neutron dosemeter, it is best to use for calibration the line at 560 keV emitted and detected in the same device.