Atom-Source Development for Project 8

The Project 8 experiment aims to make a direct measurement sensitive to much of the unexplored range of neutrino masses, including all of the inverted hierarchy. Past experiments used molecular tritium, in which final states impose a large energy smearing that limits neutrino mass reach. Project 8 will use atomic tritium to reach a design sensitivity of m_β ≤ 40 meV/c². This requires about 10²⁰ tritium atoms held at tens of mK in a many-cubic-meter magnetic trap, which translates to a requirement of ≳ 10¹⁹ atoms/s at the atom source.

We are performing laboratory measurements and simulations to prepare for the 1-cubic-meter Atomic Tritium Demonstrator in Phase III of Project 8. This will confirm that we can produce, cool, and trap sufficient atomic tritium for the final Phase IV experiment.

Current work includes measuring the output of a tritium-compatible atom source with 20 sccm of H₂, 20 times higher than published values; improvements in atom-detection SNR; corrections for systematic effects; calculations of the required atom flux into the trap; and simulations-driven optimization of the cooling stages downstream of the atom source.