Angular response of a W-collimated room-temperature-operated CdZnTe Frisch collar spectrometer

The spatial resolution of a collimated CdZnTe Frisch collar detector was experimentally investigated for two different tungsten collimator designs using a 198Au gamma-ray source at 412 keV. A two-dimensional model for the detector–collimator–source geometry was developed and applied with some simplifying assumptions. The CdZnTe detector was fabricated from a single crystal using a copper shim as the Frisch collar. The detector fabrication process is briefly described. Pulse height spectra were collected from 241Am, 198Au and 137Cs using a 3.4×3.4×5.8 mm3 CdZnTe detector utilizing an insulated Frisch collar mounted inside a tungsten collimator. The resulting energy spectra are presented. Room-temperature energy resolution of 1.72% full-width at half-maximum (FWHM) was obtained for 137Cs at 662 keV without electronic correction. The two-dimensional model reasonably predicts the angular response of the CdZnTe detectors when inserted into two different collimators.