Development of a microcalorimeter array for wide energy band X-ray astronomy

Abstract

Some experience has been acquired by the CEA/DSM/DAPNIA/SAp in IR bolometer arrays realization in collaboration with the LETI (Grenoble). From this basis, we are undertaking a development of an X-ray sensitive array for X-ray astronomy imaging spectroscopy missions. We are conservative in using only standard and well-known silicon processing technologies. An implanted and diffused silicon MESA structure is used, in place of ionic multi-implanted silicon, to provide the thermal sensor. Using this technology, we expect to obtain a set of homogeneous sensor of high volume, and low noise. The absorber will be a high Z material. HgTe is a candidate, high Z superconducting alternatives are explored. The absorber is hybridized, with indium beads providing a thermomechanical coupling, to the sensor plate. The microcalorimeter is decoupled from the cold sink by narrow silicon beams, following the structure already used for the IR arrays. The extrapolation of the X-ray thermal sensor is presently being pursued. Measurements of the characteristics of the sensors of the last batch of array prototypes are presented. With this standard silicon technology, we expect to obtain a low spread in sensor parameters, as is required by a multiplexed readout scheme.