Gießen 2007 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 15: Kern- und Teilchen-Astrophysik

HK 15.3: Talk

Tuesday, March 13, 2007, 14:45–15:00, E

Measurement of ³He(α,γ)⁷Be with ERNA Recoil Separator — •Antonino Di Leva for the ERNA collaboration — Experimentalphysik III, Ruhr Universität Bochum

The ³He(α,γ)⁷Be reaction plays an important role in the interpretation of the results of the solar neutrino experiments, since the estimate of the oscillation parameters relies on the solar neutrino spectrum, calculated by solar models. The high energy component in this spectrum is mainly produced by the decay of ⁷Be and ⁸B. The uncertainty in the ³He(α,γ)⁷Be cross section is also one of the largest contributions to the uncertainty on the predicted primordial ⁷Li abundance in Big Bang Nucleosynthesis calculations.

Previous measurements of the ³He(α,γ)⁷Be cross section have been performed detecting the capture γ-rays or, alternatively, measuring the activity of the synthesized ⁷Be. While the results of the two different approaches agree on the energy dependence of the astrophysical S factor, they disagree in the extrapolated S₃₄(0) value at a 3σ level.

A novel approach uses the European Recoil separator for Nuclear Astrophysics (ERNA) to detect directly the ⁷Be ions produced in the reaction and, additionally, the coincident detection of the capture γ-rays. Experiment and results are presented.

Supported by DFG(Ro 429/35-3) and INFN