Gießen 2007 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 15: Kern- und Teilchen-Astrophysik

HK 15.1: Vortrag

Dienstag, 13. März 2007, 14:15–14:30, E

The ³He(α,γ)⁷Be reaction studied at LUNA — •Daniel Bemmerer^1,2, Ralf Kunz³, Michele Marta^1,4, Claus Rolfs³, Frank Strieder³, and Hanns-Peter Trautvetter³ for the LUNA collaboration — ¹Institut für Strahlenphysik, Forschungszentrum Dresden-Rossendorf — ²INFN Padua — ³Institut für Experimentalphysik III, Ruhr-Universität Bochum — ⁴INFN Milano

The nuclear physics input from the ³He(α,γ)⁷Be cross section is a major uncertainty in the fluxes of ⁷Be and ⁸B neutrinos from the Sun predicted by solar models and in the ⁷Li abundance obtained in big-bang nucleosynthesis calculations. Here we report on a precision cross section measurement performed by the LUNA collaboration at Gran Sasso (Italy). At energies directly relevant to big-bang nucleosynthesis, the cross section has been studied by both the activation [1] and the prompt-γ technique. Using a windowless gas target, high beam intensity, a low background in beam γ-detector and low background γ-counting facilities, the ³He(α,γ)⁷Be cross section has been determined at 90–170 keV center-of-mass energy with a total uncertainty as low as 4 %. The new data can be used in big-bang nucleosynthesis calculations and to constrain the extrapolation of the ³He(α,γ)⁷Be astrophysical S-factor to solar energies.

[1] D. Bemmerer et al., Phys. Rev. Lett. 97, 122502 (2006)