Millikelvin Atomic Tritium for Project 8

The most powerful technique for directly studying the absolute neutrino mass is spectroscopy of beta-decay electrons at the endpoint of the spectrum. Project 8 has pioneered a new frequency-based method, cyclotron radiation emission spectroscopy (CRES) to reach a sensitivity of 40 meV/c². Atomic tritium is key to this sensitivity. Since T atoms recombine to T₂ on (most) surfaces, Project 8 will magnetically cool, slow, and trap the atoms. The atomic system will begin with producing a high flux of atoms (> 10¹⁹/s), likely in a 2500 K tungsten tube. Surface collisions will cool these to ∼ 20 K. Atoms will then enter a magnetic evaporative cooling beamline (MECB) to evaporate away energy in the beam while also converting forward momentum to internal energy for removal by evaporation. Finally, the slowed 1 mK atoms will pass through a small opening into a > 10 m³ magneto-gravitaitonal trap, giving a steady-state density of ~ 10¹⁷ m⁻³. Compatibility with CRES imposes several coupled requirements on the magnetic design, so joint CRES-atomic design is a major focus of the collaboration. This contribution will highlight the present status of Project 8’s calculation, simulation, and prototyping work on the atomic system and show how these efforts support our design sensitivity to the absolute neutrino mass.