Results from the First Al-Based Sensors for the BeEST Experiment*

The (Be)ryllium (E)lectron-capture in (S)uperconducting (T)unnel junction Experiment (BeEST) has used tantalum-based superconducting (STJ) sensors to place world-leading limits on the existence of neutrino states beyond those in the Standard Model (SM). However, materials dependent effects such as the modification of the electron states of the implanted radioisotope require further systematic study. As such, replication of the experiment with beryllium implanted into aluminum electrodes offers an eloquent way to identify how the behavior of the STJ sensors change when measuring recoil inside a given host medium. This talk presents the data analyzed from the first fabricated Al-STJs and discusses the results' value toward constraining materials-dependent effects, a critical step towards future phases of the BeEST experiment.