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Phys. Rev. C 68, 065803 (2003) [21 pages]

Precise measurement of the 7Be(p,γ)8B S factor

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A. R. Junghans*, E. C. Mohrmann†, K. A. Snover‡, T. D. Steiger§, E. G. Adelberger, J. M. Casandjian**, and H. E. Swanson
Center for Experimental Nuclear Physics and Astrophysics, University of Washington, Seattle, Washington 98195, USA

L. Buchmann, S. H. Park††, A. Zyuzin, and A. M. Laird
TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, Canada V6T 2A3

Received 1 August 2003; published 17 December 2003

We present new measurements of the 7Be(p,γ)8B cross section from E̅ c.m.=116 to 2460 keV (where c.m. means center-of-mass), which incorporate several improvements over our previously published experiment, also discussed here. Our new measurements lead to S17(0)=22.1±0.6(expt)±0.6(theor) eV b based on data from E̅ c.m.=116 to 362 keV, where the central value is based on the theory of Descouvemont and Baye. The theoretical error estimate is based on the fit of 12 different theories to our low-energy data. We compare our results to other S17(0) values extracted from both direct [7Be(p,γ)8B] and indirect (Coulomb-dissociation and heavy-ion reaction) measurements, and show that the results of these three types of experiments are not mutually compatible. We recommend a “best” value, S17(0)=21.4±0.5(expt)±0.6(theor) eV b, based on the mean of all modern direct measurements below the 1+ resonance. We also present S factors at 20 keV which is near the center of the Gamow window: the result of our measurements is S17(20)=21.4±0.6(expt)±0.6(theor) eV b, and the recommended value is S17(20)=20.6±0.5(expt)±0.6(theor) eV b.

© 2003 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevC.68.065803
DOI:
10.1103/PhysRevC.68.065803
PACS:
26.20.+f, 26.65.+t, 25.40.Lw

*Present address: Forschungszentrum Rossendorf, Postfach 510119, 01324 Dresden, Germany. Electronic address: A.Junghans@fz-rossendorf.de

†Electronic address: mohrmann@u.washington.edu

‡Electronic address: snover@u.washington.edu

§Present address: Cymer, Inc., 17075 Thornmint Ct., San Diego, CA 92127.

**Permanent address: GANIL, B.P. 5027, 14021 Caen Cedex, France.

††Present address: Dept. Physics, Seoul Nat. Univ., Seoul 151-742, Rep. of Korea.

See Also

See Also: A. R. Junghans, K. A. Snover, E. C. Mohrmann, E. G. Adelberger, and L. Buchmann, Updated S factors for the 7Be(p,γ)8B reaction, Phys. Rev. C 81, 012801 (2010).

 
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