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HK: Physik der Hadronen und Kerne
HK 48: Nuclear and Particle Astrophysics IV
HK 48.6: Talk
Thursday, March 11, 2004, 17:45–18:00, F
Measurement of the 3He(α,γ)7Be cross section with ERNA — •Antonino Di Leva — Institut für 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, which gave strong hints or reported about neutrino
oscillations.
Indeed, the estimate of the oscillation parameters relies on the solar
neutrino spectrum which is calculated by solar models: the relative rate of
3He(α,γ)7Be with respect to the rate of
3He(3He,2p)4He determines the high energy
component of the solar neutrino spectrum,
that is mostly produced by the decay of 7Be and 8B.
Previous measurements of the cross section for the 3He(α,γ)7Be reaction have been performed detecting the capture gamma 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, that suggests the presence of systematic errors in one or both of the techniques, or, possibly, a non radiative component in the cross section.
A novel approach to study this reaction relies on the European Recoil separator for Nuclear Astrophysics (ERNA), that can provide the simultaneous detection of both the capture gamma rays and the 7Be ions produced in the reaction. In this talk, the experiment and its feasibility are discussed.