PT Journal AU Inderbitzin, K Engel, A Schilling, A Il'in, K Siegel, M TI An ultra-fast superconducting Nb nanowire single-photon detector for soft x-rays JI Appl. Phys. Lett. PY 2012 VL 101 DE SSPD; SNSPD; x-ray; Nb AB Although superconducting nanowire single-photon detectors (SNSPDs) are well studied regarding thedetection of infrared/optical photons and keV-molecules, no studies on continuous x-ray photoncounting by thick-film detectors have been reported so far. We fabricated a 100 nm thick niobiumx-ray SNSPD (an X-SNSPD) and studied its detection capability of photons with keV-energies incontinuous 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 extendedmeasurement periods. Strikingly, the signal amplitude distribution depends significantly on the photonenergy spectrum.VC ER