The front-end electronics of the Spectrometer Telescope for Imaging X-Rays (STIX) on the ESA Solar Orbiter satellite

• Published in: Journal of instrumentation Vol. 7; no. 12; p. C12015
• Main Authors: Grimm, O, Bednarzik, M, Commichau, V, Graczyk, R, Gröbelbauer, H P, Hurford, G, Krucker, S, Limousin, O, Meuris, A, Orleański, P, Przepiórka, A, Seweryn, K, Skup, K, Viertel, G
• Format: Journal Article
• Language: English
• Published: 01.12.2012
• Subjects: Crystals; Electronics; Imaging; Missions; Space telescopes; Spectrometers; Sun; X-rays
• ISSN: 1748-0221; 1748-0221
• DOI: 10.1088/1748-0221/7/12/C12015

Solar Orbiter is an ESA mission to study the heliosphere in proximity to the Sun, scheduled for launch in January 2017. It carries a suite of ten instruments for comprehensiveremote-sensing and in-situ measurements. The Spectrometer Telescope for Imaging X-Rays (STIX), one of the remote sensing instruments, images X-rays between 4 and 150 keV using an Fourier technique. The angular resolutionis 7 arcsec and the spectral resolution 1 keV full-width-half-maximum at 6 keV. X-ray detectionuses pixelized Cadmium Telluride crystals provided by the Paul Scherrer Institute. The crystalsare bonded to read-out hybrids developed by CEA Saclay, called Caliste-SO, incorporating a lownoise, low-power analog front-end ASIC IDeF-X HD. The crystals are cooled to -20 degree C to obtainvery low leakage currents of less than 60 pA per pixel, the prerequisite for obtaining the requiredspectral resolution. This article briefly describes the mission goals and then details the front-end electronics design and main challenges, resulting in part from the allocation limit in mass of 7 kg and in power of 4 W. Emphasis is placed on the design influence of the cooling requirement within the warmenvironment of a mission approaching the Sun to within the orbit of Mercury. The design for the long-term inflight energy calibration is also explained.