Activation measurement of the He3(α,γ)Be7 cross section at low energy

D. Bemmerer, F. Confortola, H. Costantini, A. Formicola, Gy Gyürky, R. Bonetti, C. Broggini, P. Corvisiero, Z. Elekes, Zs Fülöp, G. Gervino, A. Guglielmetti, C. Gustavino, G. Imbriani, M. Junker, M. Laubenstein, A. Lemut, B. Limata, V. Lozza, M. MartaR. Menegazzo, P. Prati, V. Roca, C. Rolfs, C. Rossi Alvarez, E. Somorjai, O. Straniero, F. Strieder, F. Terrasi, H. P. Trautvetter

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133 Citations (Scopus)


The nuclear physics input from the He3(α,γ)Be7 cross section is a major uncertainty in the fluxes of Be7 and B8 neutrinos from the Sun predicted by solar models and in the Li7 abundance obtained in big-bang nucleosynthesis calculations. The present work reports on a new precision experiment using the activation technique at energies directly relevant to big-bang nucleosynthesis. Previously such low energies had been reached experimentally only by the prompt-γ technique and with inferior precision. Using a windowless gas target, high beam intensity, and low background γ-counting facilities, the He3(α,γ)Be7 cross section has been determined at 127, 148, and 169 keV center-of-mass energy with a total uncertainty of 4%. The sources of systematic uncertainty are discussed in detail. The present data can be used in big-bang nucleosynthesis calculations and to constrain the extrapolation of the He3(α,γ)Be7 astrophysical S factor to solar energies.

Original languageEnglish
Article number122502
JournalPhysical review letters
Issue number12
Publication statusPublished - Sep 25 2006

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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    Bemmerer, D., Confortola, F., Costantini, H., Formicola, A., Gyürky, G., Bonetti, R., Broggini, C., Corvisiero, P., Elekes, Z., Fülöp, Z., Gervino, G., Guglielmetti, A., Gustavino, C., Imbriani, G., Junker, M., Laubenstein, M., Lemut, A., Limata, B., Lozza, V., ... Trautvetter, H. P. (2006). Activation measurement of the He3(α,γ)Be7 cross section at low energy. Physical review letters, 97(12), [122502].