DEVELOPMENT OF MICROCALORIMETERS FOR HIGH-RESOLUTION X-RAY SPECTROSCOPY

We have been developing microcalorimeters for use in X-ray spectroscop y. These devices have very high spectral resolution (several eV) and h igh intrinsic quantum efficiency, making them particularly useful for astrophysical applications. Work has evolved over a 10 year period fro m simple proof-of-concept devices to functional arrays. An energy reso lution of 7.3 eV at 6 keV has been demonstrated for the smallest absor bers used, and a resolution of approximately 12 eV for devices with a pixel area of approximately 1/4 mm2. Present work is focused on making 36 pixel monolithic arrays with individual pixel areas of up to appro ximately 1 mm2. As the size of the absorbing area is increased, high s pectral resolution is more difficult to achieve not only because of th e increased heat capacity, but also because of problems with uniform t hermalization. We have observed non-ideal effects in large absorbers t hat must be controlled and minimized before the fabrication of low noi se, larger area microcalorimeters can be accomplished.