Characterization of a CdZnTe detector for a low-power CubeSat application

Abstract

We report spectral and imaging performance of a pixelated CdZnTe detector custom designed for the MeVCube project: a small Compton telescope on a CubeSat platform. MeVCube is expected to cover the energy range between 200 keV and 4 MeV, with performance comparable to the last generation of larger satellites. In order to achieve this goal, an energy resolution of few percent in full width at half maximum (FWHM) and a 3-D spatial resolution of few millimeters for the individual detectors are needed. The severe power constraints present in small satellites require very low power read-out electronics for the detector. Our read-out is based on the VATA450.3 ASIC developed by Ideas, with a power consumption of only 0.25 mW/channel, which exhibits good performance in terms of dynamic range, noise and linearity. A 2.0 cm × 2.0 cm × 1.5 cm CdZnTe detector, with a custom 8 × 8 pixel anode structure read-out by a VATA450.3 ASIC, has been tested. A preliminary read-out system for the cathode, based on a discrete Amptek A250F charge sensitive pre-amplifier and a DRS4 ASIC, has been implemented. An energy resolution around 3% FWHM has been measured at a gamma energy of 662 keV; at 200 keV the average energy resolution is 6.5%, decreasing to 2% at energies above 1 MeV. A 3-D spatial resolution of ≈ 2 mm is achieved.

Introducing the MeVCube concept: a CubeSat for MeV observations

“…In this analysis the effective area is computed as the number of correctly reconstructed events, passing the selection cuts, divided by the number of simulated events and scaled by the [19]. The energy resolution of the single CdZnTe detector has been measured in [1].…”

“…Moreover, the ASIC has already been selected for space operation in the past [35]. Performance of the read-out electronics and a custom designed detector have extensively been measured at DESY; the main results are presented in [1]. The main specifications and requirements for the MeVCube Compton camera are summarized in Table 1.…”

“…COMP-TEL's data are taken from[19]. The energy resolution of the single CdZnTe detector has been measured in[1].…”

“…Main specifications and requirements for the MeVCube Compton telescope. Performance like the energy resolution and the spatial resolution are based on the measurements performed in[1].…”

Introducing the MeVCube concept: a CubeSat for MeV observations

“…The scientific payload is based on two layers of pixelated Cadmium-Zinc-Telluride (CdZnTe) detectors, coupled with low-power read-out electronics (ASIC, VATA450.3). The performance of the read-out electronics and CdZnTe custom designed detectors have been measured extensively at DESY [1]. The performance of the telescope is accessed through simulations: despite a small effective area limited to a few cm 2 , MeVCube can reach an angular resolution of 1.5 • and a sensitivity comparable to the one achieved by the last generation of large-scale satellites like COMPTEL and INTEGRAL.…”