NBN MGO/NBN SUPERCONDUCTING TUNNEL-JUNCTIONS AS X-RAY-DETECTORS/

We report on our work using NbN/MgO/NbN junctions for the detection of x-rays. Detectors based on superconducting tunneling junctions offer the prospect of energy resolution over an order of magnitude higher th an is obtainable with the current generation of semiconductor-based de tectors NbN is interesting due to the possibility of its use in trappi ng layer devices. The junctions were fabricated at the NASA Jet Propul sion Laboratory (JPL) with an area of 4 mum by 4 mum. They were tested at the Naval Research Laboratory (NRL) in an applied magnetic field o f approximately 250 gauss, a current bias of several hundred nanoamps and an operating temperature of 1.7 K.