Current Status of the Heavy Neutrino Search using the BeEST Experiment Phase-III Data

The Beryllium Electron capture in Superconducting Tunnel junctions (BeEST) experiment searches for evidence of heavy neutrino mass eigenstates in the decay of $^7$Be by precisely measuring the nuclear recoil energy of the $^7$Li daughter nucleus. In the current Phase-III, the BeEST has expanded the experiment to a 36-pixel array of superconducting sensors and increased the dose of implanted $^7$Be. We present the status of the BeEST Phase-III and highlight the refined experimental and analytical techniques in Phase-III. We also discuss an improved analysis scheme using pulse shape discrimination enabled by a new continuous data acquisition system.