Toward large μ-calorimeters x-ray matrices based on metal-insulator sensors and HEMTs/SiGe cryo-electronics

ABSTRACT The launch of ASTRO-H/ITOMI ,the X-ray Japanese/US mission, in February 2016 with -calorimeters basedon Metal-Insulator-Sensors (M.I.S) experiment with a 4.5eV spectral resolution, would certainly generate re-newed interest on the high impedance M.I.S based on Si P:B. Since 2009 we are involved in a large programto build a camera consisting of a 2x2 mosaic of 32x32 pixel matrices using this sensor type. Since we relyon very similar approach of ASTRO-H/ITOMI design, we have concentred our e orts on the use of collectiveall-silicon technologies only. We have already presented the building block such as thermometers, sensors andcryo-electronics. Now, thanks to our new 32x32 CAD, we are today in the process of building 4 32x32 matri-ces per wafer. ASTRO-H/SXS uses degenerated Si as output wiring of the pixel and an HgTe semi-conductorabsorber. Thanks to the use of superconducting wiring and composite superconducting Tantalum absorber, wehope to enhance the spectral resolution of this matrix onto that of SXS. Moreover, our development bene ts of anultra low power consumption Cryo-Electronics chain. This chain is based on High Electron Mobility Transistors(HEMTs, with an AsGa/AlAsGa hetero-junction) and SiGe ASICs, and handles 34:1 multiplexing. It has beensuccessfully tested under cryogenic conditions. The composite Tantalum absorber have been tested with 6keVX-rays, and our M.I.S. exhibit good and homogeneous sensitivity. To be compatible with the 1 W@50mK ther-mal budget allowed in present day spatial cryo-coolers, we have also developed new thermal insulation techniquesthat will allow us to easily handle more than 4000 independent pixels within this tiny power budget.Keywords: X-rays Astronomy, -Calorimeter, M.I.S., Cryo-Electronics, Tantalum hybrid Absorber