Speaker
Description
The primordial abundances of light elements produced during Big Bang Nucleosynthesis (BBN) provide a powerful probe of the cosmological baryon density. Precise nuclear reaction data for these processes are essential to constrain the models. Among these, the 2H(p, $\gamma$)3He and D+D fusion reactions govern the deuterium abundance and are the key sources of uncertainty in its predicted primordial value, while the 3He($\alpha$, $\gamma$)7Be reaction determines the primordial 7Li abundance. The latter reaction is also a key process in solar hydrogen burning, directly influencing the predicted solar neutrino fluxes. The 2H(p, $\gamma$)3He reaction has been the main source of uncertainty in deuterium destruction for many years. It was previously measured at BBN energies by the LUNA collaboration using a windowless gas-target system, covering energies of 33–270 keV. However, higher-energy measurements with solid targets show a 10% disagreement, revealing a tension between the low- and high-energy datasets. To resolve this discrepancy and to provide new data for theoretical ab-initio calculations, a new measurement was performed at the Felsenkeller underground laboratory in Dresden, Germany, covering energies of 200–1200 keV and partially overlapping the existing datasets.Using a similar setup, the angular distribution of the 3He($\alpha$, $\gamma$)7Be reaction was also studied at energies of 442–1213 keV. This talk will present an overview of BBN and the related nuclear measurements at the Felsenkeller underground laboratory in Dresden. Goals, experimental setups, new results from 2H(p, $\gamma$)3He and 3He($\alpha$, $\gamma$)7Be measured at Felsenkeller as well as future plans will be shown.