An X-ray photon-counting imaging spectrometer based on a Ta absorber with four superconducting tunnel junctions

We present the first results obtained with a two-dimensional X-ray imaging spectrometer consisting of a 200 x 200 mu m(2) Ta absorber and read out by four Ta/Al superconducting tunnel junctions (STJs). A preliminary image rec onstruction algorithm allows the visualisation of the diffraction pattern f rom a 5 mu m pinhole illuminated with 10 keV X-rays. The image suggests a s patial resolution better than 10 mu m The algorithm does not take into acco unt quasi-particle losses in the absorber. Hence, the pulse-height reconstr uction is not optimal and the energy resolution varies significantly across the absorber. The best energy resolution is obtained for a 20 x 20 mu m(2) area in the centre of the absorber. and amounts to similar to 77 eV at a p hoton energy of 5895 eV, with a 70 eV electronic noise contribution, (C) 20 00 Elsevier Science B.V. All rights reserved.