The Tritium Recoil-Ion Mass Spectrometer Experiment

Abstract

The Tritium Recoil-Ion Mass Spectrometer (TRIMS) experiment measures the branching ratio between bound ($^3$HeT$^+$) and unbound (T$^+$, $^3$He$^+$) ions that are produced by molecular tritium (T$_2$) beta-decay. This measurement will help validate the current molecular final-state theory utilized by direct neutrino mass experiments such as KATRIN and Project 8. The TRIMS experiment sets up a uniform guiding magnetic field of \SI{0.24}{\tesla} and a uniform electric field of \SI{60}{kV}/\SI{25}{cm} that run parallel to each other and coaxial with a cylindrical acceleration chamber. Inside the chamber, tritium decays and the product ions are accelerated toward a silicon ion detector at the cathode and the betas to a silicon beta detector at the anode. By performing energy and time of flight measurements of the coincident ions and betas, TRIMS can categorize these events and so derives the branching ratio in question. The preliminary results from the TRIMS experiment are in agreement with the modern theory.