Recent Developments in Thick Mercuric Iodide Spectrometers

Thick (~l cm) mercuric iodide gamma-ray detectors have been produced which show spectroscopic qualities at moderate detector biases (~5 kV) comparable to those of thin spectrometers. Efficiency measurements indicate that the entire volume of the detectors is active. Spectra resolutions of less than 10% have been obtained for gamma-ray energies above 1 MeV. Short charge collection times have produced the best results. Measurement of crystal charge transport properties is discussed. A small amount of bias conditioning is necessary for best performance. Operating parameters of the detectors have been investigated.