Timing techniques for improving thick Hgl2 gamma-ray detector performance

Spectroscopy in thick HgI2 γ-ray detectors is limited by low hole mobility, short hole trapping times, and nonuniform internal electric fields. Estimates of ne, the charge deposited by a γ-ray absorption event, thus depend upon the event location d. Determining d then allows a more precise estimate of ne than is possible from collected charge alone. We theoretically examine the concept of timing the duration of the electron current flow to determine d and show how d is employed to produce an accurate ne value. A modeling study shows that 1 to 2 cm thick HgI2 detectors are capable, in principle, of 1% resolution at 662 keV with photopeak efficiencies of 6-12%. (orig.)