Microfabricated transition-edge x-ray detectors

We are developing high performance x-ray detectors based on superconducting transition-edge sensors (TES) for application in materials analysis and as tronomy. Using our recently developed fully lithographic TES fabrication pr ocess, we have made devices with an energy resolution of 4.5 +/- 0.1 eV for 5.9 keV x-rays, the best reported energy resolution for any energy dispers ive detectors in this energy range. These detectors utilize micromachined t hermal isolation structures and transition-edge sensors fabricated from Mo/ Cu bilayers with normal-metal boundary conditions. We have found the normal -metal boundary conditions to be critical to stable and reproducible low no ise operation. In this paper we present details of fabrication and performa nce of these devices.