Superconducting single X-ray photon detector based on W0.8Si0.2

TL;DR

This paper reports the development and characterization of a superconducting W0.8Si0.2-based single X-ray photon detector capable of high efficiency and low dark counts at temperatures near 4.8 K, with potential for improved design.

Contribution

It introduces a novel superconducting W0.8Si0.2 detector for X-ray photons and demonstrates its high performance and operational stability at cryogenic temperatures.

Findings

Critical temperature of 4.97 K

Operates effectively up to 4.8 K

Negligible dark counts at high bias currents

Abstract

We fabricated a superconducting single X-ray photon detector based on W0.8Si0.2, and we characterized its basic detection performance for keV-photons at different temperatures. The detector has a critical temperature of 4.97 K, and it is able to be operated up to 4.8 K, just below the critical temperature. The detector starts to react to X-ray photons at relatively low bias currents, less than 1% of Ic at T = 1.8 K, and it shows a saturated count rate dependence on bias current at all temperatures, indicating that the optimum internal quantum efficiency can always be reached. Dark counts are negligible up to the highest investigated bias currents (99% of Ic) and operating temperature (4.8 K). The latching effect affects the detector performance at all temperatures due to the fast recovery of the bias current; however, further modifications of the device geometry are expected to reduce the tendency for latching.