Development of an orthogonal-stripe CdZnTe gamma radiation imaging spectrometer

We report, performance measurements of a sub-millimeter resolution CdZnTe strip detector developed as a prototype for astronomical instruments operating with good efficiency in the 30-300 keV photon energy range. The prototype is a 1.4 mm thick, 64 x 64 contact stripe CdZnTe array of 0.375 mm pitch in both dimensions. Pulse height spectra were recorded in orthogonal-stripe coincidence mode which demonstrate room-temperature energy resolution < 10 keV (FWHM) for 122 keV photons with a peak-to-valley ratio > 5:1. Good response is also demonstrated at higher energies using a coplanar grid readout configuration. Spatial resolution capabilities finer than the stripe pitch are demonstrated. We present the image of a Ba-133 source viewed through a collimator slit produced by a 4 x 4 stripe detector segment. Charge signals from electron and hole collecting contacts are also discussed.