The XRS system – the first cryogenic X-ray detector in orbit

The X-ray Spectrometer, XRS on board the ASTRO-E satellite is a cryogenic X-ray detector system utilizing a micro calorimeter array of 32 pixels operating at 60 mK. An energy resolution of about 12 eV (FWHM) has been obtained across the array in the ground calibration measurements. We adopted a unique three-stage cryogenic system consisting of solid neon, liquid helium, and an adiabatic de-magnetization refrigerator to obtain a long cryogenic lifetime in orbit. The design of the neon tank was optimized to obtain about 2 yr of the neon lifetime, which determines the lifetime of the whole cryogenic system.