Speaker
Description
keV-scale sterile neutrinos are well-motivated warm dark matter candidates. While astrophysical constraints rely on cosmological assumptions, laboratory beta-decay measurements provide a complementary and largely model-independent approach by searching for spectral distortions. The LiFE-SNS project measures the full tritium beta-decay spectrum using neutron-irradiated LiF crystals with embedded tritium, read out by a magnetic microcalorimeter operated at millikelvin temperatures. This configuration enables high energy resolution and high detection efficiency over the entire beta-energy range.
We report results from the first 10-day dataset of Phase I. The measured spectrum is compared with a precise theoretical model that incorporates detector response and analysis effects. A spectral fit is performed to search for the characteristic kink-like signature induced by mixing with a keV-scale sterile neutrino, with systematic uncertainties carefully evaluated. These initial results demonstrate the performance of the LiFE-SNS technique and establish the analysis framework for the full Phase-I dataset and future higher-statistics measurements.