Study of the ²H(α,γ)⁶Li reaction at LUNA

Observations of very metal-poor stars have yielded evidence for the less abundant lithium isotope ⁶Li in several cases. These findings prompt the question whether there is a non-negligible primordial contribution to the observed ⁶Li abundances. Network calculations show that the ²H(α,γ)⁶Li reaction dominates ⁶Li production in the Big Bang. A recent Coulomb dissociation work on this reaction produced only an upper limit for the astrophysical S-factor. At the 400 kV underground accelerator LUNA in Gran Sasso/Italy, an experiment is underway to gain direct cross section data, but the background is formidable. Preliminary data of the first phase of the LUNA experiment will be shown, and an outlook will be given.