Characterization of single-sided cadmium zinc telluride strip detectors for high energy astrophysics applications

Cadmium zinc telluride (CdZnTe or CZT) was introduced as a new room temperature semiconductor detector due to its good energy resolution, high atomic number, high density and good stopping power in the early 1990s. UNH has focused on developing CZT strip detector designs for astrophysical measurement applications in the 0.05 to 1 MeV photon energy range. This thesis presents characterization efforts of two types of single-sided CZT strip detector: non-charge sharing orthogonal coplanar strip detectors and charge-sharing strip detectors. The characterization includes spectroscopy, imaging, uniformity and efficiency measurements. Measured energy resolutions with both detector designs are better than those obtainable with NaI(Tl), the scintillator detector material most often used in this energy range. The 3-D imaging capabilities of the detectors were studied using collimated 122 keV photons. Spatial resolution is better than the unit cell pitch in the x and y dimension, and less than 1 mm in the z dimension for both designs. The detection efficiency for photopeak events was calculated for the single-sided charge-sharing CZT strip detector. We also report on Monte Carlo simulations (GEANT4 v7.1) to investigate the effect of multi-hits on detector performance for both spectroscopy and imaging. We compare simulation results with data obtained from laboratory measurements and discuss the implications for future strip detector designs