The3He(?,?)7Be reaction and the solar neutrino problem

Abstract

The capture reaction 3He(c~, y)TBe has been investigated in the energy range of E .... = 107 to 1,266 keV. The 4He or 3He beams of up to 300 gA particle current were incident on 3He or 4He gas targets, respectively. The gas target systems were all of the windowless and recirculating type. Excitation functions have been obtained with the use of an extended-static gas target, while the measurements of y-ray angular distributions involved a quasi-point supersonic jet system. The determination of absolute cross sections has been carried out with both types of gas target systems. The 7-ray yields in the 3He(~, 7)7Be reaction were detected using 80 cm 3 Ge(Li) detectors. The data lead to a zero-energy intercept of the astrophysical S(E) factor of S(0)=0.30+0.03 keV-b. This result reduces the calculated solar neutrino rate by a factor of 1.76.Nuclear Reactions: 3He(~, 7)7Be, E ..... = 107 to 1,266 keV; measured o-(E, E~,, 07.); deduced spectroscopic factors and astrophysical S-factor; solar neutrino problem; extended and quasi-point jet gas targets, Ge(Li) detectors.

Activation measurement of the reaction cross section at high energies

“…The 3 He(α, γ) 7 Be reaction is an excellent example of those reactions which preserve their importance over several decades despite many experimental and theoretical studies devoted to them. The crucial role played by the 3 He(α, γ) 7 Be reaction in solar hydrogen burning was realized more than 50 years ago, when H.D.…”

“…The crucial role played by the 3 He(α, γ) 7 Be reaction in solar hydrogen burning was realized more than 50 years ago, when H.D. Holmgren and R.L.…”

“…This result indicated that the 2nd and 3rd pp-chains [3] century. The data are from [4,5,6,7,8,11]. The Gamow-windows relevant for the solar hydrogen burning via the pp-chain and for the big-bang nucleosynthesis are also shown at the bottom of the figure.…”

“…Several experimental studies followed this pioneering work in the next decades aiming at the determination of the 3 He(α, γ) 7 Be cross section at energies as low as possible in order to approach the astrophysically relevant energy range [4,5,6,7,8,9,10,11]. This energy range, the so called Gamow window, lies between about 15 and 30 keV at 15 MK temperature relevant for the solar core.…”

“…The solar neutrino problem has been solved by the discovery of neutrino oscillation [13,14] and the flux of 7 Be and 8 B solar neutrinos can now be measured with a precision of about 3-4 % by various neutrino detectors [15,16,17,18]. The measured neutrino fluxes can therefore be used to probe the solar core and test solar models if the underlying nuclear physics input, i.e.…”