Modeling the TRIMS Experiment

By analyzing the kinematics of tritium beta decay, one can directly measure the neutrino-mass scale. Since modern tritium-based experiments use a molecular source and molecular excitations modify the beta spectrum, one must also understand these ``final-state'' excitations precisely in order to properly analyze the spectral shape. Historical mass spectroscopy measurements disagreed with theory. The Tritium Recoil-Ion Mass Spectrometer (TRIMS) experiment is a coincidence time-of-flight mass spectrometer designed to test the theory used in the neutrino-mass analysis. In this presentation, I will speak in detail about the Geant4 modeling of the TRIMS experiment, which explains features in the data such as secondary emission and dissociation in flight.