Radiation effects in superconducting-tunnel-junction X-ray detectors

Niobium superconducting-tunnel-junction X-ray detectors were irradiated by high-energy protons typical of those found in space. Deterioration of the energy resolution was observed together with an increase of the leakage current and a nonuniform charge collection due to local regions having a reduced superconducting-energy-gap in niobium electrodes. These two changes are analogous to those in semiconductor detectors, although the detection principles are different.