The Role of Atomic Tritium in Future Neutrino Mass Experiments
Dr. Larisa Thorne (Johannes Gutenberg-University Mainz)

Nearly 70 years since the neutrino was discovered, and 25 years since discovery of neutrino oscillations established its non-zero mass, the absolute neutrino-mass scale remains unknown.

Tritium beta decay endpoint measurements currently offer the best upper limit on the neutrino mass. A next-generation experiment with greater sensitivity must overcome one of the major systematics for this kind of measurement: the molecular nature of the beta source. Past and current tritium beta decay experiments use a molecular tritium source in which one of the tritium atoms undergoes decay. A fraction of the decay energy excites the molecule into rotational, vibrational, or electronic excited states; this causes broadening in the molecule's final state distribution (FSD), and has a smearing effect on the beta decay spectrum. In order to achieve a reduced systematic uncertainty due to this FSD smearing, next-generation experiments must switch to an atomic tritium source.

I will present an overview of the necessary steps to develop such an atomic tritium source, through the lens of the Project 8 experiment. This multi-institution development program includes dissociation and accommodation cooling down to 10K; further cooling to 10mK via magnetic evaporative cooling; and atom trapping using magnet arrays. In addition to this overview, I will focus on the multitude of tritium-compatible diagnostic tools being developed at JGU Mainz to measure atom flux, atom beam shape, and temperature.