Cryogenic detectors based on transition edge sensor (TES) microcalorimeters, magnetic microcalorimeters (MMCs), and superconducting tunnel junctions (STJs) are becoming increasingly attractive for several commercial applications including x-ray, gamma-ray and alpha particle spectroscopy for x-ray microanalysis, x-ray fluorescence, and nuclear forensics and non-proliferation. All of these detector applications require precision temperature control for proper operation of the detector arrays. Monitoring the temperature at the end of a cold finger or snout where the detector arrays typically are located is very difficult using a conventional resistive thermometer, which also can produce erroneously high readings due to self-heating effects. Noise thermometers are superior in this regard, but their slow response time (~10 s) and limited resolution (~1%) make these thermometers less attractive for precision temperature measurements. The precision thin-film magnetic thermometer described in this proposal will offer an attractive solution for precision temperature control for all of these commercial detector applications.
Several potential NASA missions stand to benefit from the proposed magnetic thermometer development effort, in particular missions that include instrumentation with arrays of cryogenic detectors requiring precision temperature control for a variety of spectroscopy applications. Potential missions include the measurement of the polarization of the Cosmic Microwave Background (CMBPol), Single Aperture Far-Infrared Observatory (SAFIR), International X-ray Observatory (IXO), and the space-based interferometer Submillimeter Probe of the Evolution of Cosmic Structure (SPECS). The innovative magnetic thermometer with integrated SQUID readout described in this proposal is easy to use, features a compact design to simplify integration, and will meet targeted needs for fast, high-resolution (better than 1 µK/Hz½) temperature control for these missions.
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