Building large area CZT imaging detectors for a wide-field hard X-ray telescope—ProtoEXIST1

Abstract

We have constructed a moderately large area (32 cm 2 ), fine pixel (2.5 mm pixel, 5 mm thick) CZT imaging detector which constitutes the first section of a detector module (256 cm 2 ) developed for a balloon-borne wide-field hard X-ray telescope, ProtoEXIST1. ProtoEXIST1 is a prototype for the High Energy Telescope (HET) in the Energetic X-ray imaging Survey Telescope (EXIST), a next generation space-borne multi-wavelength telescope. We have constructed a large (nearly gapless) detector plane through a modularization scheme by tiling of a large number of 2 cm × 2 cm CZT crystals. Our innovative packaging method is ideal for many applications such as coded-aperture imaging, where a large, continuous detector plane is desirable for the optimal performance. Currently we have been able to achieve an energy resolution of 3.2 keV (FWHM) at 59.6 keV on average, which is exceptional considering the moderate pixel size and the number of detectors in simultaneous operation. We expect to complete two modules (512 cm 2 ) within the next few months as more CZT becomes available. We plan to test the performance of these detectors in a near space environment in a series of high altitude balloon flights, the first of which is scheduled for Fall 2009. These detector modules are the first in a series of progressively more sophisticated detector units and packaging schemes planned for ProtoEXIST2 & 3, which will demonstrate the technology required for the advanced CZT imaging detectors (0.6 mm pixel, 4.5 m 2 area) required in EXIST/HET.

Size and distribution of Te inclusions in THM as-grown CZT wafers: The effect of the rate of crystal cooling

“…Its several opportune properties, that is band gap, high density, and high absorption-coefficient for nuclear radiation, along with its good electronic-transport properties and its growth as a high-resistivity boule, make it a very attractive material to be used as room-temperature nuclear-detectors for homeland security, astronomy, and medical imaging [1][2][3][4][5].…”

Growth and interface study of 2in diameter CdZnTe by THM technique

“…CZT has long been known as a good substrate material for HgCdTe due to its lattice matching for the IR detector and night vision applications [1][2][3]. However, CZT has attracted most of the attention from researchers and industries as a room temperature nuclear detector material [4][5][6][7][8]. Its excellent optoelectronic properties and appropriate band gap with high average atomic number ( $50) makes CZT the ideal semiconductor for nuclear detector applications operable at room temperature.…”

Overview of EXIST mission science and implementation

“…1 and Table 2), has been described by Hong et al 34,35,36 . Here we provide an overview including some aspects not previously discussed.…”