Low-energy behavior of the ^3He(α, γ)^7Be cross section

Abstract

Cross sections for the ^3He(α, γ)^7Be reaction have been measured at several energies from E_(c.m.) = 165 to 1169 keV by counting prompt γ-rays from a windowless, differentially pumped, recirculating, ^3He gas target. The cross-section factor S_(34)(E_(c.m.)) and branching ratio γ_1/γ_0 were determined at each energy. Cross sections were also measured at E_(c.m.) = 947 and 1255 keV by counting the γ-rays from the ^7Be produced in a ^3He gas cell with a Ni entrance foil. Combining the results of these two independent experiments yields a zero-energy intercept for the cross-section factor of S_(34)(0) = 0.53 ± 0.03 keV · b. The relationship between these measurements and several theoretical calculations, and the import of the extrapolated cross section for the solar-neutrino problem are discussed.

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