Activation measurement of the 3He(alpha,gamma)7Be cross section at low energy.
The nuclear physics input from the 3He(alpha,gamma)7Be cross section is a major uncertainty in the fluxes of 7Be and 8B neutrinos from the Sun predicted by solar models and in the 7Li 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-gamma technique and with inferior precision. Using a windowless gas target, high beam intensity, and low background gamma-counting facilities, the 3He(alpha,gamma)7Be 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 3He(alpha,gamma)7Be astrophysical S factor to solar energies.
Bemmerer
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Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Padova, via Marzolo 8, 35131 Padova, Italy.
Confortola
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Costantini
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Formicola
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Gyürky
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Bonetti
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Broggini
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Corvisiero
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Elekes
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Fülöp
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Gervino
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Guglielmetti
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Gustavino
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Imbriani
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Junker
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Laubenstein
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Lemut
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Limata
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Lozza
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Marta
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Menegazzo
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Prati
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Roca
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Rolfs
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Alvarez
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Somorjai
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Straniero
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Strieder
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Terrasi
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Trautvetter
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