High-Resolution Aluminum STJ Sensors with In-Situ Laser Calibration for the BeEST Sterile Neutrino Search
ORAL
Abstract
The BeEST (Beryllium Electron-capture with Superconducting Tunnel junctions) experiment explores beyond-standard-model physics by precisely measuring the 7Li recoil energy from 7Be electron capture. This two-body decay provides a sensitive probe of the existence of ~keV-scale sterile neutrinos. We present the development progress on the latest generation of aluminum-based superconducting tunnel junction (STJ) sensors, optimized for detecting eV-scale nuclear recoils from implanted 7Be atoms. These devices leverage aluminum's lower atomic number and smaller superconducting gap, achieving sufficient energy resolution to operate alongside our existing tantalum-based sensors. In this talk, we present the details of the Al STJ array design and show their performance when exposed to both UV laser pulses and nuclear decay events. This capability marks an important step towards the future Phases of the BeEST experimental campaign.
*The BeEST experiment is funded in part by the Gordon and Betty Moore Foundation (10.37807/GBMF11571), the DOE-SC Office of Nuclear Physics under AwardNumbers DE-SC0021245 and DE-FG02-93ER40789, and the LLNL Laboratory Directed Research and Development program through Grants No. 19-FS-027 andNo. 20-LW-006. TRIUMF receives federal funding via a contribution agreement with the National Research Council of Canada. The theoretical work was performedas part of the European Metrology Programme for Innovation and Research (EMPIR) Projects No. 17FUN02 MetroMMC and No. 20FUN09 PrimA-LTD. This workwas performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC5207NA27344.
