An ultra-fast superconducting Nb nanowire single-photon detector for soft X-rays

TL;DR

This paper reports the development of a 100 nm thick niobium superconducting nanowire detector capable of continuous, low-noise detection of keV X-ray photons, demonstrating unique energy-dependent signal characteristics.

Contribution

It introduces a novel thick-film niobium X-ray SNSPD capable of continuous mode detection at very low bias currents with no dark counts, expanding SNSPD applications to X-ray detection.

Findings

Detects keV X-ray photons at bias currents as low as 0.4%

No dark counts observed during extended measurements

Signal amplitude varies significantly with photon energy spectrum

Abstract

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.