Abstract
The cross section of 7Be(p,γ)8B represents one of the most important nuclear inputs for the prediction of the high energy component of solar neutrinos and it has also a direct impact on the 7Li abundance after the Big Bang Nucleosynthesis. The importance of this reaction triggered an intense experimental work over the last decades, where discrepancies were observed between the results of different measurements. In addition, a question remains about possible common systematic effects, considering that all measurements share the same experimental approach, i.e. an intense proton beam impinging on a 7Be radioactive target. Inverse kinematics, i.e. a 7Be ion beam and a hydrogen target, with the direct measurement of the total reaction cross section by means of the detection of the 8B recoils, can shed light on such systematic effects. Efforts attempted so far were limited by the low 7Be beam intensity. We present here the results of a new measurement at Ecm = 376 to 819 keV using a high intensity 7Be beam in combination with a windowless gas target and the recoil mass separator ERNA (European Recoil mass separator for Nuclear Astrophysics) at CIRCE (Center for Isotopic Research on Cultural and Environmental heritage), Caserta, Italy. Our results, including the systematic error, are compatible with previous measurements that yields lower value of S17(0) and are compatible with the currently accepted value from [1] only at a 2-σ level.
Highlights
The solar neutrinos of 7Be to 8B have a great interest, since they represent a large fraction of the high energy solar neutrino flux
We present here a new experiment exploiting the same method with the much higher ion beam intensity available at the Tandem Accelerator Laboratory at CIRCE (Center for Isotopic Reasearch on Cultural and Environmental heritage), Dept. of Mathematics and Physics, University of Campania ”L
Until 2009 the recoil mass separator ERNA was installed at the Dynamitron Tandem Laboratorium of the Ruhr Universität Bochum, Germany
Summary
The solar neutrinos of 7Be to 8B have a great interest, since they represent a large fraction of the high energy solar neutrino flux. The importance of 7Be to 8B neutrinos ratio triggered several experiments to determine cross section of 7Be(p, γ)8B at the relevant astrophysical energies [2,3,4,5,6,7,8,9,10,11,12] and the 7Be half-life in different environments [13,14,15,16]. An alternative approach using a radioactive ion beam and a hydrogen gas target was attempted in [12], and later in [17] In both cases a recoil mass separator was employed to detect the 8B recoils. Those experiments could not achieve a sufficient precision because of the low ion beam intensity (≈ 107 pps). Vanvitelli”, Italy, where a 7Be ion beam is routinely produced [18] with an intensity up to 109 pps
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