Study of the7be(p, γ)-reaction

Abstract

The cross section of the 7Be(p, y)8B reaction has been determined at Ep = 360 keV to 0360 =0.17+0.04 lab.

Precise measurement of theBe7(p,γ)B8Junghans1, Mohrmann2, Snover3 et al. 2003Phys. Rev. C140342794View full textAdd to dashboardCite

“…Studies of high-energy neutrinos produced by 8 B decay in the sun have shown that when these neutrinos are detected on earth the number that remain electron neutrinos (ν e 's) is only about half of the number that have oscillated into other active species [1]. Precise predictions of the production rate of 8 B solar neutrinos are important for testing solar models, and for limiting the allowed neutrino mixing parameters including possible contributions of sterile species.…”

“…ies of the 7 Be(p,γ) 8 B cross section [4,5,6,7,8,9,10,11,12,13,14,15], and indirect studies using Coulombbreakup [16,17,18,19,20] or peripheral heavy-ion transfer and breakup [21,22] reactions. The direct technique has the advantage that it studies the reaction that actually occurs in the sun, but is difficult experimentally because it requires a radioactive target or beam, and the cross sections are small.…”

“…The first [14] used a target of 106 mCi initial activity (here called BE1 [23]) to measure the 7 Be(p,γ) 8 B cross section at mean center-ofmass proton energies,Ē cm = 186 to 1203 keV, including the M1 resonance nearĒ cm = 630 keV. The α-detector solid angle in this experiment was determined using a 7 Li(d,p) 8 Li reaction yield ratio. In a second, abbreviated measurement with a new 7 Be target of similar activity (called BE2), we determined the cross section in the rangeĒ cm = 876 to 2459 keV.…”

“…In a second, abbreviated measurement with a new 7 Be target of similar activity (called BE2), we determined the cross section in the rangeĒ cm = 876 to 2459 keV. In this second measurement, we became concerned over possible inaccuracies in the 7 Li(d,p) 8 Li reaction yield ratio method for determining the α-detector solid angle, which relied on calculated extrapolations of the continuous α-spectrum tail below the experimental cutoff (a similar but smaller extrapolation is necessary to interpret the 7 Be(p,γ) 8 B reaction yields).…”

“…Recently we completed a 7 Be(p,γ) 8 B measurement with a 340 mCi target (called BE3) that incorporated several improvements over the BE1 experiment, including a thinner Si surface-barrier detector for which the correction (and hence the uncertainty) due to the fraction of the 8 B β-delayed α-spectrum lost below the detector threshold was minimal. We avoided using the 7 Li(d,p) 8 Li reaction for solid angle normalization, using instead a custom-made 148 Gd α-source fabricated on a backing of the same design as the one used for the 7 Be target.…”