Proton capture cross section ofBe7and the flux of high energy solar neutrinos

Abstract

The low energy cross section for the Be(p,y) B reaction has been measured by detecting the delayed e particles from the 'B beta decay. Detailed discussion is presented of the analysis of the radioactive Be target including the use of two independent methods to determine the Be areal density. The direct capture part of the cross section is subtracted from the total cross section to deduce resonance parameters for the 1+ first excited state in B. The zero-energy astrophysical S factor inferred from the present experiment is compared with previous values. The effect on the Cl solar neutrino capture rate, predicted by the standard solar model, is also discussed.

Coulomb Dissociation ofB8and the Low-Energy Cross Section of theBe7Schümann1, Hammache2, Typel3 et al. 2003Phys. Rev. Lett.873420View full textAdd to dashboardCite

“…Very recently, the latter has been redetermined by new high-precision direct measurements [4,5,6,7] and extrapolated to zero energy with the help of a theoretical model [8]. The resulting zero-energy astrophysical S factors, S 17 (0), however, do not always agree within their quoted errors: Hammache et al [4] found S 17 (0) = 18.8 ± 1.7 eV b, in agreement with other direct-capture data [5,9,10]. In contrast, Junghans et al [6] report a considerably larger value, S 17 (0) = 22.3 ± 0.7 ± 0.5 eV b.…”

“…The opposite behaviour is noted above the M1 resonance: our data and those of Refs. [6,7] match excellently, whereas the other (p,γ) experiments [4,5,9,10] consistently report lower values. We want to emphasize the remarkably good agreement of our CD data up to 1.1 MeV with the most recent direct-proton-capture experiment where an ion- Ref.…”

“…In the following, we have restricted the angles θ 8 to values below 0.62 • to ensure both dominance of CD and reduction of the effect of any possible E2 contribution. The data are compared to a simulation with GEANT that includes two electromagnetic multipole components: a resonant M1 contribution located at E rel =0.63 MeV with resonance parameters taken from Filippone et al [10], and the non-resonant E1 contribution from our theoretical model as described above. The latter was scaled by a normalization factor of 0.79.…”

Standard solar neutrinos

“…(1) uncertainties in the measured cross sections at laboratory energies, (2) The "average cross section" which they extrapolated to solar energies was obtained by averaging cross sections which differ by many standard deviations and have different energy shapes (the cross sections measured by Kavanagh (1960) and by Parker (1968) differ by more than 3σ from the cross sections measured later by Vaughn (1970) and by Filippone (1983) Dar and Shaviv (1994) noted that sub-Coulomb radiative captures and transfer reactions take place mainly when the colliding nuclei are far apart. They argued that since optical models describe well the shapes of the bound state and relative motion wave functions outside the nuclear potential, they should be preferred for extrapolating the laboratory cross sections to solar energies.…”

Deuteron-induced nucleon transfer reactions within anab initioframework: First application top-shell nuclei

“…1). The inelastic and transfer scattering of deuteron on 7 Li targets has been repeatedly measured in connection with the measurement of the radiative proton capture on 7 Be [23][24][25][26][27][28][29]. The main resonant peak at ∼0.60 MeV above the deuteron+ 7 Li threshold in the 9 Be spectrum (corresponding to deuterons of ∼0.78 MeV kinetic energy), needs to be accurately measured in order to calibrate the mean areal density of 7 Be atoms in the targets used in the proton-capture measurement [30].…”