Latest Results from the BeEST Phase III

by Inwook Kim (Lawrence Livermore National Laboratory)

Tuesday 22 Apr 2025, 12:30 → 13:30 America/Los_Angeles

48/2-224 - Madrone (SLAC)

The Beryllium Electron capture in Superconducting Tunnel junctions (BeEST) experiment aims to detect signatures of sub-MeV sterile neutrinos in the decay of Be-7 by precisely measuring the nuclear recoil energy of the Li-7 daughter nucleus using superconducting tunnel junction (STJ) cryogenic sensors. In its Phase-III, the experiment was scaled from a single STJ sensor to a 36-pixel array of STJ sensors to increase the statistics and mitigate gamma-induced backgrounds. A new continuous data acquisition system with offline analysis capabilities was implemented, increasing flexibility in signal processing and data cleaning. We developed automated, robust procedures for signal processing and spectral fitting to analyze large datasets efficiently. In this talk, we highlight the refined experimental and analytical techniques implemented in Phase III and present the latest results from the BeEST Phase III.