Charge trapping correction in Ge spectrometers

Abstract

A charge-trapping model is developed which does not require the assumption of shallow-level detrapping. The model shows the charge-trapping deficit to be proportional to S/sub 0/t/sup N/, where S/sub 0/ is the peak amplitude of the shaping amplifier pulse, t is the charge collection time for the carrier being trapped, and 1.5<N<3 for most practical cases. A class of circuits to correct for charge trapping was developed and tested; the results were used to evaluate the main features of the model. A radiation-damaged, conventional electrode detector and a reverse electrode detector, which exhibited a significant amount of deep-level, majority-carrier charge trapping, were used to evaluate the usefulness of the circuits. At the 1.33-MeV /sup 60/Co line, the uncorrected FWHM (full width at half maximum) of the radiation-damaged detector was 4.3 keV, while the N=2.3 corrected FWHM was 2.00 keV. The uncorrected FWHM of the reverse electrode detector was 2.20 keV, while the N=3 corrected FWHM was 1.84 keV. Results indicate that deep-level trapping was the dominant mechanism.<<ETX>>