Speaker
Description
The BeEST experiment searches for physics beyond the standard model (BSM) in the neutrino sector by utilizing the electron capture (EC) decay of 7Be. The 7Be is embedded in superconducting tunnel junction (STJ) sensors such that the low-energy (eV-scale) decay products are detected with high energy resolution and efficiency. Modelling of low-energy backgrounds is crucial to understanding potential beyond standard model (BSM) physics, including low-energy phonon and quasiparticle generation within the superconductors. In this talk, modelling methods for phonon dynamics in cryogenic silica are described in detail for use with G4CMP. Phonon properties calculated include scattering parameters, isotopic scattering rate, anharmonic decay rate, fractional phonon density of states based on phonon modes, etc. Beyond the BeEST experiment, accurate modelling of phonon dynamics is of significant importance for simulating the impact of radiation on quantum sensing regimes.
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 Award Numbers DE-SC0021245 and DE-FG02-93ER40789, and the LLNL Laboratory Directed Research and Development program through Grants No. 19-FS-027 and No. 20-LW-006. TRIUMF receives federal funding via a contribution agreement with the National Research Council of Canada. The theoretical work was performed as part of the European Metrology Programme for Innovation and Research (EMPIR) Projects No. 17FUN02 MetroMMC and No. 20FUN09 PrimA-LTD. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52- 07NA27344.
