MC²-1K, a Novel 250 µm CdTe based Imaging Spectrometer for Space Science

¹ Université Paris-Saclay, Université Paris Cité, CEA, CNRS, AIM, 91191 Gif-sur-Yvette, France
² Kavli IPMU (WPI), UTIAS, The University of Tokyo, Kashiwa, Chiba 277-8583, Japan
³ CEA, IRFU, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France
⁴ 3D PLUS SA, 78530 Buc, France
⁵ iMAGINE-X Inc., 1-12-8 Shibuya, Tokyo 150-0002, Japan

^* This email address is being protected from spambots. You need JavaScript enabled to view it.

Published online: 6 November 2025

Abstract

Hard X-ray focusing optics technologies for solar physics space missions aiming at direct imaging of solar flares or hard X-ray space astronomy are challenging the development of time-resolved, high spectral and spatial resolution CdTe detectors. CEA and 3D PLUS, in the framework of the ALB3DO laboratory and with the support of the French space agency CNES, have initiated the development of an entirely new detector named MC². In the midterm, the detector will be a scalable, 4-side buttable 3D module including a 64 × 64-pixel CdTe sensor with a pitch of 250 µm. The patterned pixel sensor is flip-chipped on top of a mosaic of four full-custom readout ASICs named IDeF-X D²R₂. In the development path, a preliminary prototype has been constructed and operated successfully. The device, named MC²-1K, consists of a quarter of the MC² module, i.e. a 32 × 32-pixel CdTe detector with a 250 µm pitch flip chipped on top of a single IDeF-X D²R₂ ASIC circuit. The hybrid detector is mounted onto a printed circuit board and installed into a vacuum chamber, associated with a dedicated readout bench comprised of the custom-made 32-channel Wilkinson ADC OWB-1 for system studies and performance assessment in a frame readout mode. An energy-calibrated spectrum comprising 958 channels has been successfully recorded under illumination with a ²⁴¹Am source. An energy resolution of 910 eV FWHM at 59.54 keV has been measured. This paper describes the detector prototype and demonstrates its first performance results. Performance limitations will be discussed and future work towards an entire module, which will be integrated in 3D, will be described.