On the development of a superconducting-tunnel-junction array for X-ray astronomy

Arrays of superconducting tunnel junctions (STJs) provide the possibility to perform high-resolution imaging spectrophotometry at X-ray wavelengths. We describe the applications of STJ arrays to X-ray astronomy, and present measurements on a 3 x 3 test array of Nb/Al-based STJs, operated at a temperature of 1.2 K, which illustrate the current photometric and spectroscopic capabilities of such devices. These results demonstrate the basic experimental feasibility of STJ arrays and indicate that there are no fundamental problems to be expected in the development of large-format X-ray detector arrays based on STJs.