Low energy elastic scattering of hydrogen, deuterium, and tritium on helium isotopes

Abstract Motivated by the needs of atomic tritium sources for neutrino mass experiments and Doppler-free two-photon 1 S–2 S spectroscopy in atomic deuterium and tritium, we present calculations of energy-dependent elastic scattering cross sections of hydrogen isotopes (H, D, and T) on helium isotopes ( 3 He and 4 He) in the temperature range 1 mK to 300 K. The tritium-on-helium cross sections are found to be enhanced over their hydrogen-on-helium counterparts by a near-threshold resonant s -wave bound state at low energy, similar to one that has been predicted in the triplet T–T system. While the energy-dependent cross sections span a wide range at low energy due to this s -wave enhancement, they tend toward a common value at high energy where the scattering becomes effectively geometric in nature.