First light of MC2-1K, a 250 μm pixel pitch CdTe imaging spectrometer for hard X-ray astronomy

The next generation of hard X-ray space telescopes for astrophysics and solar physics requires the development of focal planes with high detection efficiency above 10 keV and enhanced spectroscopic imaging performance. We designed and produced MC2-1K, the first prototype of a new family of fine pitch hybrid detectors. It consists of a 32 × 32 pixel CdTe semiconductor detector point-to-point connected to the spectroscopic channels of a full-custom ASIC. The ASIC named D2R2 was produced in 2019 in the XFAB 0.18 μm technology and has the same 250 μm pixel pitch as the detector. We demonstrated a median equivalent charge noise of 54 e- RMS, equivalent to an energy resolution of 654 eV at 31 keV for a CdTe detector. We developed an acquisition system where the signals of D2R2’s 32 rows are encoded in parallel by a 32-channel ADC ASIC, OWB-1. The custom daughter board with the hybrid detector is placed in a thermally controlled vacuum chamber for a moderate cooling. This paper will present the characterization tests of the ASIC, the dedicated test set-up and the first spectroscopic measurements of the MC2-1K hybrid detector.