A simulation of CdTe gamma ray detectors based on collection efficiency profiles as determined by lateral IBIC

Collection efficiency profiles as determined by the Ion Beam Induced Charge (IBIC) technique have been considered to evaluate the spectroscopic performances of a cadmium telluride (CdTe) nuclear radiation detector. The dependence of such profiles on the applied bias voltage and the shaping time are presented and discussed on the basis of a theoretical model, which is also used to evaluate the electron/hole collection lengths profiles. Experimental collection efficiency profiles were used as input data of the "ISIDE" Monte Carlo programme to simulate the CdTe response to gamma rays produced by 57Co. A systematic investigation of such spectra obtained under different detection conditions shows the effects of non constant collection efficiency profiles and ballistic deficit on the energy resolution of the detector.