Astrophysical S factor for the He-4(He-3,gamma)Be-7 reaction at medium energies

3 pags., 1 tab. -- Nuclear Physics in Astrophysics V 3–8 April 2011, Eilat, IsraelThe astrophysical S factor for the He-4(He-3,gamma)Be-7 direct capture reaction plays a major role in the context of solar neutrino flux and primordial Li-7 abundances that demand accurate information on the reaction. We report here our recent cross section measurements using the activation method in the region of E-CM=900-2800 keV, that aim to shed light on the discrepancies in the existing data and lead to a more accurate extrapolation of the S factor

Constraining the Astrophysical S-Factor of the 3He(α, γ)7Be Reaction

ITO International Research Center, on the campus of the University of Tokyo, June 1 to 6, 2014; http://ribf.riken.jp/ARIS2014/index.htmlDue to its relevance to the Standard Solar Model and to the Big Bang Nucleosynthesis calculations, the cross section of the 3He(α, γ)7Be reaction have been widely studied both from the theoretical and the experimental fronts. We report here on cross section measurements in the energy region Ec.m.=1- 3 MeV using the direct recoil counting method in an attempt to solve the discrepancies among the previous data sets and calculations in this energy region and thus to constrain the extrapolations of the S34(E) curve to astrophysical energies.Peer Reviewe

New measurement of the 3He(α,γ)7Be cross section at medium energies

We report on a new cross-section measurement for the 3He(α, γ)7Be reaction at three medium energies of E c.m. between 1 and 3 MeV. The interest stems from the significant role played by the reaction in calculating an accurate solar neutrino flux and the primordial 7Li abundance. The energy dependence of the astrophysical S 34 factor observed in the present work, especially above 1 MeV, highlights the need to constrain theories in order to obtain a precise extrapolated value for S 34(0). In this context, a comparison with the recent theoretical work in a fully microscopic fermionic molecular dynamics approach and a few other representative calculations emphasize the need for further experimental as well as theoretical work to resolve the existing conflicts. ©2012 American Physical Society.Supported by the UK STFC and was partly financed by the Spanish Research Funding Agency CICYT under Project FPA2009-07387. Further, M.C.G. acknowledges his CSIC-JAEpredoc grant partly funded by the European Social Funds.Peer Reviewe

He(α,γ) 7 Be Reaction

Due to its relevance to the Standard Solar Model and to the Big Bang Nucleosynthesis calculations, the cross section of the 3 He(α,γ