TES microcalorimeter for IXO: From focal plane to anticoincidence detector

The high resolution spectroscopy provides a unique technique to extract fundamental information in X-ray Astrophysics and Cosmology. In order to exploit at the best the capability of carrying out spectroscopy of faint sources, great care must be taken to reduce the background in the main detector. In this paper, we will present the working principle of a TES (Transition Edge Sensor) Microcalorimeter, its application for fine spectroscopy and a novel anticoincidence technique , based itself on a TES detector. Recent results from the first sample of the IXO-anticoincidence detector will be also shown.