Current Status of Non-equilibrium Superconducting Detectors for Photons and Molecules

摘要

Particle detection with non-equilibrium superconductivity was initiated in 1949. High-energy a-particles of MeV were detected by a superconducting stripline detector (SSLD). In 1969, the pulse signals for high-energy a-particles were also produced by a superconducting tunnel junction (STJ). The extremely low average-energy of a few ineV (1.7Δ) required to produce a quasiparticle, which was precisely calculated in 1982, is crucial in detecting low energy quanta and realizing high-energy resolution spectroscopy. Since then enormous amount of studies have been devoted to realize advanced analytical instruments exhibiting unconventional high-performance on sensitivity, covering energy range, and spectroscopic resolution. The progress in detector performance has been brought by nanoprocessing technologies. These days, finely-patterned non-equilibrium superconducting detectors are being employed to detect low energy quanta that have energies of more than three orders smaller than MeV of the above pioneering works: eV - keV photons via photoelectric effects and keV proteins via phonons created upon particle impacts on the detector surface. We summarize the current status in astronomy, x-ray material analysis, THz imaging, mass spectrometry, and try to mention the future prospect.