An ultra-fast superconducting Nb nanowire single-photon detector for   soft X-rays
  Although superconducting nanowire single-photon detectors (SNSPDs) are well studied regarding the detection of infrared/optical photons and keV-molecules, no studies on continuous X-ray photon counting by thick-film detectors have been reported so far. We fabricated a 100 nm thick niobium X-ray SNSPD (an X-SNSPD), and studied its detection capability of photons with keV-energies in continuous mode. The detector is capable to detect photons even at reduced bias currents of 0.4%, which is in sharp contrast to optical thin-film SNSPDs. No dark counts were recorded in extended measurement periods. Strikingly, the signal amplitude distribution depends significantly on the photon energy spectrum. 
Kevin Inderbitzin (1), Andreas Engel (1), Andreas Schilling (1),   Konstantin Il'in (2), Michael Siegel (2) ((1) Physics Ins...
cond-mat.supr-con cond-mat.mes-hall physics.ins-det