Development of Superconducting Tunnel Junction X-ray Detector with High Absorption Yields Utilizing Silicon Pixel Absorbers

Abstract

A superconducting tunnel junction (STJ) array detector along with silicon pixel absorbers (STJ–SPA) is fabricated to achieve high detection efficiency at X-ray energies below 10 keV. The STJ pixels have dimensions of 100 \(\upmu \)m \(\times \) 100 \(\upmu \)m and are composed of Nb–Al/AlO\(_{X}\)/Al–Nb thin layers. The SPAs are also 100 \(\upmu \)m \(\times \) 100 \(\upmu \)m and have a depth of 400 \(\upmu \)m, and are isolated from each other by a deep trench with a depth of 350 \(\upmu \)m. The detection efficiency of the STJ–SPA exceeds 95 % at X-ray energies below 10 keV, and its energy resolution is 82 eV FWHM, as measured at the Si K\(\upalpha \) line at 1740 eV. By means of the STJ–SPA detector, the X-ray absorption spectrum of the light element sulfur with a concentration of less than 0.1 wt% in a soda-lime glass sample was successfully acquired.