Development of superconducting tunnel junctions as an energy-dispersive detector for UV and visible photons

摘要

We are developing an energy-dispersive detector for UV and visible photons that uses superconducting tunnel junctions (STJs) with Al trapping layers. As a first step to achieve this, we evaluated the performance of the detector for extreme ultraviolet (EUV) photons by using a synchrotron radiation facility. We achieved an energy resolution of FWHM = 17.8 +- 0.6 eV (including electrical noise of 17.6 +- 0.2 eV) for 55 eV EUV photons with a 100 x 100 μm~2 STJ. The electrical noise was the main component of the energy resolution. We achieved the electrical noise of FWHM = 2.1 +- 0.1 eV for a 20 x 20 μm~2 STJ by replacing the cables connecting the STJ to a preamplifier operated at room temperature. A stronger signal resulting from a thinner tunnel barrier will lead to better energy resolution for detecting UV and visible photons.