Electronics for the detectors of SOFIA's next generation instrument: the HIgh-Resolution Mid-infrarEd Spectrometer (HIRMES)

The HIgh-Resolution Mid-infrarEd Spectrometer (HIRMES) is the 3rd Generation Instrument for the Stratospheric Observatory For Infrared Astronomy (SOFIA). The HIRMES cryostat is comprised of several cooling stages (300K, 65K, 4K, 800mK, 400mK, and 70mK), which are essential to achieve the required sensitivity on the mid-infrared waveband in which HIRMES observes (25 um-122um). The science application of the HIRMES instrument is the study of proto-planetary systems that contain water-vapor, water-ice, deuterated hydrogen, and neutral oxygen. In this paper, we discuss the use of a He3 stage coupled to an Adiabatic Demagnetization Refrigerator (ADR) stage in order to achieve the required temperature of 70mK on the Focal Plane Assembly (FPA). HIRMES' FPA contains two Transitioning Edge Sensor (TES) bolometric detector arrays that can provide a combination of four primary observing modes; High Resolution (R ~ 100,000), Mid-Resolution (R ~ 10,000), Low-Resolution (R ~ 600) spectroscopy, and Spectral Imaging (R ~ 2000).1 Moreover, we discuss the operations of the detector readout, in combination of a grating-dispersive spectroscopy mechanism, and a host of Fabry-Perot tunable narrow-band filters to achieve HIRMES' unmatched sensitivity in all four modes.