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.
@article{arxiv.1208.1656,
title = {An ultra-fast superconducting Nb nanowire single-photon detector for soft X-rays},
author = {Kevin Inderbitzin and Andreas Engel and Andreas Schilling and Konstantin Il'in and Michael Siegel},
journal= {arXiv preprint arXiv:1208.1656},
year = {2012}
}