An introduction to superconducting tunnel junction detectors

Superconducting tunnel junction (STJ) detectors have potential as ultra-high-energy resolution detectors, Recently, single-junction detectors, where radiation is directly absorbed and detected by an STJ, have shown much higher energy resolutions than semiconductor detectors even at high count rates of over 10(4) counts per second, e,g, resolutions of 12 eV for 5.9 keV x-rays, 6 eV for 277 eV x-rays and 0.2 eV for 2 eV optical photons. The energy resolutions of series-junction detectors, where radiation is absorbed by a single-crystal substrate and the resulting non-thermal phonons are detected by STJs connected in series on the substrate, are not Set better than those of semiconductor detectors but are improving rapidly. This paper briefly introduces some principles of STJ detectors and reviews their recent developments, Copyright (C) 2000 John Wiley & Sons, Ltd.