Cryogenic supersonic beams of hydrogen and deuterium atoms

Slowly moving, high density beams of atomic hydrogen isotopes are of interest for precision tests of fundamental physics, including measurements of the absolute neutrino mass [1,2]. With these applications in mind, we have developed a cryogenically-cooled supersonic beam source of hydrogen and deuterium atoms. This source is based upon the dissociation of H₂ or D₂ molecules in an electron-seeded discharge at the exit of a pulsed valve operated at 34 K. The phase space characteristics of the beams have been measured by resonance enhanced multi-photon ionization spectroscopy. The ground-state hydrogen atoms in these beams, with longitudinal speeds of ~900 m/s, are well suited for confinement in magnetic storage rings. The way in which the beams are operated is compatible with the production of tritium atoms by dissociation of T₂ molecules for absolute neutrino mass measurements.

[1] S. Scheidegger, D. Schlander, J. A Agner, H. Schmutz, P. Jansen and F. Merkt, J. Phys. B: At. Mol. Opt. Phys. 55 155002 (2022)

[2] S. Scheidegger, J. A. Agner, H. Schmutz and F. Merkt, Phys. Rev. A 108, 042803 (2023)

[2] A. A. Esfahani et al., J. Phys. G: Nucl. Part. Phys. 44 054004 (2017)