An ion trap source of cold atomic hydrogen via photodissociation of the BaH+molecular ion

Abstract

I present a novel scheme for producing cold (magnetically trappable) atomic hydrogen, based on threshold photodissociation of the BaH+ molecular ion. BaH+ can be sympathetically cooled using laser cooled Ba+ in an ion trap, before it is photodissociated on the single photon A1ς+ ← X1ς+ transition. The small mass ratio between Ba+ and BaH+ ensures a strong overlap within the ion trap for sympathetic cooling, while the large mass ratio between BaH+ and H means that the released hydrogen can be up to 139 times colder than the parent molecular ions. I examine the hydrogen production rate, and describe how the trap dynamics and photodissociation laser detuning influence the achievable energies. The low infrastructure costs and the ion trap nature of the scheme make it suitable for loading hydrogen into an antihydrogen experiment. This would support a direct matter-antimatter comparison, which could provide important clues as to why our Universe contains so little antimatter.