PERFORMANCES OF A SILICON DRIFT CHAMBER AS FAST SCINTILLATOR PHOTODETECTOR FOR GAMMA-RAY SPECTROSCOPY

The performances of a Silicon Drift Chamber (SDC), having a diameter o f 3 mm, as scintillation light photodetector have been experimentally evaluated on a prototype of gamma-ray detector employing a GSO crystal of similar cross-section. This detector presents a minimum energy thr eshold of about 50 keV at room temperature (20 degrees C) or 25 keV at 0 degrees C. The measured energy resolution at room temperature is 22 .65% and 8.73% FWHM at 122 keV and 662 keV respectively. These perform ances were obtained by using a shaping time of 0.5 mu s, which allows to operate at high gamma-ray interaction rate. The effect of the SDC d rift-time on the detector gain has been also evaluated.