SALER@FRIB: Searching for BSM Physics via Nuclear Decay in Superconducting Sensors

The Superconducting Array for Low Energy Radiation (SALER) is a new project at FRIB that will measure sub-keV decay radiation using Superconducting Tunnel Junction (STJ) quantum sensors operated “on-line” for the first time. The experimental concept is based on the success of the BeEST experiment to measure eV-scale nuclear recoils following the electron capture decay of ⁷Be for BSM neutrino physics. The initial physics goals for SALER are to search for exotic scalar and tensor currents in the weak interaction and performing high-precision beta decay measurements related to the top-row CKM unitarity test. Initial testing of the refrigeration equipment and sensors has been performed at STAR Cryoelectronics including measuring the I(V) response of the STJs. In this talk I will report on the progress of the first tests of this equipment, as well as the near-term plans for the SALER commissioning at FRIB.