Title of Presentation: Breakthrough Energy Resolution in Close-Packed Arrays of Superconducting Transition-edge X-ray Microcalorimeters

Primary (Corresponding) Author: Caroline Kilbourne

Organization of Primary Author: NASA Goddard Space Flight Center


Abstract:  We are fabricating superconducting transition-edge x-ray microcalorimeter pixels with absorbers designed to provide both rapid thermalization of the x-ray energy and a high-fill factor in arrays. We have designed absorbers that are cantilevered over the active part of the sensor itself, making contact only at normal metal features, and only in a manner that does not allow current to flow through the absorber. We mechanically stabilize the absorber via additional contact points on the silicon-nitride membrane that provides the thermal isolation for the sensor, and we have demonstrated that these contacts do not change the thermal conductance or provide a path for energy loss.  We have made absorbers with an initial evaporated gold layer followed by either electroplated gold or electroplated bismuth. With both absorber configurations, we are routinely obtaining FWHM energy resolution at 6 keV in the range 2.3 - 3.3 eV.  This is an important step towards the high-resolution, high-fill-factor, microcalorimeter arrays needed for x-ray astrophysics missions such as Constellation-X.