| 4 | | We are measuring rate coefficients for the associative detachment (AD) reaction H^^-^^ + H --> H,,2,, + e^^-^^. This is the dominant creation mechanism for forming H,,2,, during the epoch of first star and protogalaxy formation. H,,2,, acted as a coolant in primordial clouds. This cooling effect is necessary in the formation of the first stars. Knowing these rates would allow us to accurately model the formation of the first stars and see if protogalactic halos cooled down before they would have likely collided with another halo.[[br]] |
| | 4 | During the epoch of first star and protogalaxy formation the formation of these structures was mediated through H,,2,, which is an important coolant in primordial clouds. The dominant formation mechanism of H,,2,, during this epoch is the associative detachment (AD) reaction H^^-^^ + H → H2 + e^^-^^. Published values for this process differ by nearly an order of magnitude. This introduces uncertainties into cosmological models of structure formation and limits our understanding of protogalaxy formation during this epoch and of the characteristic masses and cooling times for the first stars. |
| | 5 | |
| | 6 | To study this AD reaction in the laboratory, we begin with an anion beam and use photodetachment to generate a self-merged, anion-neutral beams arrangement. Laboratory beam energies are in the keV range. Because the beams are co-propagating, center-of-mass energies from the meV to keV range will be achievable. We will observe the AD reaction by detecting fast H2+ ions formed through ionizing collisions of the AD-generated H2 with the background gas in the vacuum chamber. |
| | 7 | [[br]] |
