Experimental investigations of the (a,xn) reactions relevant for the r-process nucleosynthesis.

The fast-expanding neutron-rich neutrino-driven winds in the core-collapse supernovae are favorable scenarios for the nucleosynthesis of the light-heavy elements. Charge particle reactions, especially (a,xn), create seeds for the weak r-process populating abundances of near stable isotopes for the Sr-Ag range, for which there remains a large discrepancy between observed and predicted elemental abundances in the metal-poor halo stars. These abundances are significantly sensitive to the (a,xn) reaction rates. Only very few of these reactions had been measured in the energy range relevant for weak r-process astrophysical conditions. Theoretical calculations of reaction rates for such scenarios are very uncertain and model-dependent. In this talk, I will discuss three experiments that measured cross-sections of 85Br(a,xn),75Ga(a,xn), and 85Rb(a,xn) reactions using the HabaNERO detector at ReA3, NSCL, along with future possibilities at FRIB to measure and constrain other important (a,xn) reactions relevant for the r-process astrophysical conditions.