Mini Compton Camera Based on an Array of Virtual Frisch-Grid CdZnTe Detectors

Abstract

We constructed a mini Compton camera based on an array of CdZnTe detectors and assessed its spectral and imaging properties. The entire array consisted of $6 \times 6$ Frisch-grid CdZnTe detectors, each with a size of $6 \times 6 \times 15~\hbox{mm}^{3}$ . Since it is easier and more practical to grow small CdZnTe crystals rather than large monolithic ones, constructing a mosaic array of parallelepiped crystals can be an effective way to build a more efficient, large-volume detector. With the fully operational CdZnTe array, we measured the energy spectra for $^{133}{\rm Ba} - $ , $^{137}{\rm Cs} - $ , $^{60}{\rm Co}$ -radiation sources; we also located these sources using a Compton imaging approach. Although the Compton camera was small enough to hand-carry, its intrinsic efficiency was several orders higher than those generated in previous researches using spatially separated arrays, because our camera measured the interactions inside the CZT detector array, wherein the detector elements were positioned very close to each other. The performance of our camera was compared with that based on a pixelated detector.