Development of an orthogonal-stripe CdZnTe gamma radiation imaging spectrometer

J. R. Macri, University of New Hampshire Durham
B. A. Apotovsky, University of New Hampshire Durham
J. F. Butler, University of New Hampshire Durham
M. L. Cherry, University of New Hampshire Durham
B. K. Dann, University of New Hampshire Durham
A. Drake, University of New Hampshire Durham
F. P. Doty, University of New Hampshire Durham
T. G. Guzik, University of New Hampshire Durham
K. Larson, University of New Hampshire Durham
M. Mayer, University of New Hampshire Durham
M. L. McConnell, University of New Hampshire Durham
J. M. Ryan, University of New Hampshire Durham

Abstract

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 × 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 133Ba source viewed through a collimator slit produced by a 4 × 4 stripe detector segment. Charge signals from electron and hole collecting contacts are also discussed.