Characterisation of Pixellated CdZnTe Detectors for Use in a Portable Gamma-Ray Spectrometer

The characterization of a pixellated CdZnTe detector will be discussed in the context of the development of a portable gamma-ray spectrometer device. The device will utilize the spectroscopic properties of CdZnTe to provide both isotopic identification and directional information. The CdZnTe sensors will be configured for use as a Compton camera, maximizing the efficiency for both spectroscopy and imaging of the source being assayed. In order to achieve this, pulse shape analysis algorithms are being developed to accurately determine the position of the interaction of a gamma-ray photon within the detector. A pixellated CdZnTe detector has been scanned by moving a highly collimated source in controlled steps across the surface of the detector and taking data for a set period of time at each position. In this work, a ⁵⁷Co source has been used with a 1 mm tungsten injection collimator moved in 1 mm steps across the front face and side surfaces of the detector. The results from the preparatory work and the initial scans of the detector are discussed in this work.