Modern theories of low-energy astrophysical reactions

THE ²H(α, γ)⁶LI REACTION AT LUNA AND BIG BANG NUCLEOSYNTHETIS

“…The observed abundances of D, 3 He, and 4 He are in good agreement with calculations, confirming the overall validity of BBN theory. On the other hand, the observed abundance of 7 Li is a factor 2 ÷ 3 lower than the predicted abundance (see Fig.…”

“…Everything is enclosed in a radon box flushed with high purity N 2 , to reduce and stabilize the γ activity due to the radon decay chain. 3 He reaction (E n(cm) = 2450 keV) induce (n,n γ) reactions in the Ge detector and in the surrounding materials (lead, steel, copper), generating a beam-induced background in the γ-ray spectrum, in particular around 1.6 MeV, where the capture transition to the ground state of 6 Li is expected. To reduce the neutron production, a tube 16 cm long, with a square cross section of 2 × 2 cm 2 is inserted inside the chamber.…”

“…In its standard picture, Big Bang nucleosynthesis occurs during the first minutes of universe, with the formation of light isotopes such as D, 3 He, 4 He, 6 Li and 7 Li, through the reaction chain shown in Fig. 1.…”

“…The 2 H(α, γ) 6 Li cross section is very small at BBN energies (30 E(keV) 400), because of the repulsion between the interacting nuclei. Therefore, it has never been measured experimentally, and theoretical predictions remain uncertain [3]. This process has been experimentally studied only for energies greater than 1 MeV and around the 711 keV [4,5].…”

Erratum: Neutron spin rotation inn⃗-dscattering [Phys. Rev. C78, 014002 (2008)]

“…The AV18/UIX Hamiltonian quantitatively and successfully accounts for a wide variety of few-nucleon bound-state properties and reactions, ranging from binding energies and charge radii to electromagnetic form factors, low-energy scattering observables and electroweak capture cross sections (for a review, see Refs. [11,12]). …”