Despite the impressive progress achieved both by X-ray and gamma-ray observatories in the last few decades, the energy range between ∼ 200 keV and ∼ 50 MeV remains poorly explored. COMPTEL, on-board the Compton Gamma-Ray Observatory (CGRO, 1991-2000), opened the MeV gamma-ray band as a new window to astronomy, performing the first all-sky survey in the energy range from 0.75 to 30 MeV. More than 20 years after the de-orbit of CGRO, no successor mission is yet operating. Over the past years many concepts have been proposed, for new observatories exploring different configurations and imaging techniques; a selection of the most recent ones includes AMEGO, ETCC, GECCO and COSI. We propose here a novel concept for a Compton telescope based on the CubeSat standard, named MeVCube, with the advantages of small cost and relatively short development time. 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 cm2, 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. Combined with a large field-of-view and a moderate cost, MeVCube can be a powerful instrument for transient observations and searches of electromagnetic counterparts of gravitational wave events.

Over the past two decades, both X-ray and gamma-ray astronomy have experienced great progress. However, the region of the electromagnetic spectrum around ∼1 MeV is not so thoroughly explored. Future medium-sized gamma-ray telescopes will fill this gap in observations. As the timescale for the development and launch of a medium-class mission is ∼10 years, with substantial costs, we propose a different approach for the immediate future. In this paper, we evaluate the viability of a much smaller and cheaper detector: a nano-satellite Compton telescope, based on the CubeSat architecture. The scientific performance of this telescope would be well below that of the instrument expected for the future larger missions; however, via simulations, we estimate that such a compact telescope will achieve a performance similar to that of COMPTEL.

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 a sensitivity comparable to the one of 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 in each dimension.

Despite the impressive progresses achieved both by X-ray and gamma-ray observatories in the last decades, the energy range between ∼ 200 keV and ∼ 50 MeV remains poorly explored. COMPTEL, on-board CGRO (1991CGRO ( -2000, was the last telescope to accomplish a complete survey of the MeVsky with a relatively modest sensitivity. Missions like AMEGO have been proposed for the future, in order to fill this gap in observation; however, the time-scale for development and launch is about 10 years. On a shorter time-scale, a different approach may be profitable: MeV observations can be performed by a Compton telescope flying on a CubeSat.MeVCube is a 6U CubeSat concept currently under investigation at DESY, that could cover the energy range between hundreds of keV up to few MeVs with a sensitivity comparable to that of missions like COMPTEL and INTEGRAL. The Compton camera is based on pixelated Cadmium-Zinc-Telluride (CdZnTe) semiconductor detectors, coupled with low-power read-out electronics (ASIC, VATA450.3), ensuring a high detection efficiency and excellent energy resolution. In this work I will show measurements of the performance of a custom design CdZnTe detector and extrapolations of the expected telescope performance based on these measurements as well as simulations.

Despite the impressive progresses achieved both by X-ray and gamma-ray observatories in the last decades, the energy range between ∼ 200 keV and ∼ 50 MeV remains poorly explored. COMPTEL, on-board CGRO (1991CGRO ( -2000, was the last telescope to accomplish a complete survey of the MeVsky with a relatively modest sensitivity. Missions like AMEGO have been proposed for the future, in order to fill this gap in observation; however, the time-scale for development and launch is about 10 years. On a shorter time-scale, a different approach may be profitable: MeV observations can be performed by a Compton telescope flying on a CubeSat.MeVCube is a 6U CubeSat concept currently under investigation at DESY, that could cover the energy range between hundreds of keV up to few MeVs with a sensitivity comparable to that of missions like COMPTEL and INTEGRAL. The Compton camera is based on pixelated Cadmium-Zinc-Telluride (CdZnTe) semiconductor detectors, coupled with low-power read-out electronics (ASIC, VATA450.3), ensuring a high detection efficiency and excellent energy resolution. In this work I will show measurements of the performance of a custom design CdZnTe detector and extrapolations of the expected telescope performance based on these measurements as well as simulations.