Speaker
Dr
Carlo Gustavino
(INFN)
Description
In the first minutes of Universe light isotopes as D, $^3He$, $^4He$ were produced throughout a series of processes known as Big Bang Nucleosynthesis (BBN). The abundance of each of these isotopes, so important for the understanding of the Universe evolution, depends upon baryon density and nuclear reaction rate. In particular the precise knowledge of the cross section of the p(d,γ)$^3$He process at BBN energies (30-300 keV) is of crucial importance to establish the primordial deuterium abundance. In fact the literature data have a large uncertainty, providing a cross section lower than the one expected from cosmic microwave background (CMB) data and from direct deuterium observations in metal-poor damped Lyman-alpha systems. Nevertheless the astrophysics forecasts are in better agreement with ab initio theoretical calculations. An intense experimental effort by the LUNA collaboration is going on at the underground Gran Sasso laboratory of INFN, in order to measure the p(d,γ)$^3$He cross section, in the BBN energy window, with unprecedented precision. In fact an accurate measurement is essential to solve the puzzle of the discrepancy between ab initio predictions and the experimental fit of literature data. This presentation will shows the first results obtained by the LUNA measurements of p(d,γ)$^3$He cross section. The impact on cosmology (determination of the baryon density Ω$_B$), on particle physics (estimation of the number of effective neutrinos species $N_{eff}$) and on theoretical nuclear physics (comparison of LUNA data with recent ab initio calculations) will be discussed.
Primary author
Dr
Carlo Gustavino
(INFN)
