Single-photon 2-D imaging X-ray spectrometer employing trapping with four tunnel junctions

We are developing single-photon 2-D imaging X-ray spectrometers for applica tions in X-ray astrophysics. The devices employing a Ta strip X-ray absorbe r with Al traps and a tunnel junction at each end have been tested. They ac hieve an energy resolution of 26 eV out of 5.9 keV over a limited length (S egall, IEEE Trans., in press) with a 1-D spatial resolution of about 2 mu m over the full 160 mu m length. By analytical and numerical simulations of the quasiparticle diffusion process. we study related devices with a square Ta absorber having four traps and attached junctions to provide 2-D imagin g. The traps give charge division to the corners or to the edges of the squ are absorber. We find that these devices can give good 2-D spatial resoluti on. We discuss the operating principle and the factors which affect the spa tial resolution. (C) 2000 Elsevier Science B.V. All rights reserved.