The physics and the optimization of the XRS calorimeters on Astro-E

The X-Ray Spectrometer (XRS) instrument, scheduled to be launched as part of the Japanese X-ray astronomy satellite Astro-E in February 2000, has an array of 32 microcalorimeters at the focal plane. These calorimeters consist of ion-implanted silicon thermistors and HgTe thermalizing X-ray absorbers. These devices provide spectral resolution of 9 eV at 3 keV and 11 eV at 6 keV. The process of determining the detector parameters for this instrument will be discussed. This will include discussion of the array layout, thermal conductance of the link to the heat sink, operating temperature, thermistor size, absorber choice, and means of attaching the absorber to the thermistor bearing element. We consider the XRS calorimeters to be operating in a local optimum, with the absolute optimization yet to be performed, thus we will discuss directions for future development of this sensor technology.