[Triumf-seminars] TRIUMF Seminar today at 14:00

[postmaster at admin.triumf.ca]

Date/Time: Thu 2008-01-31 at 14:00

Location:  Auditorium          

Speaker:   Thomas Brown (University of Washington)

Title:     A precision measurement of the 3He + 4He -> 7Be astrophysical S-factor

Abstract: The 3He(a,g)7Be reaction provides the principle route to energetic neutrino production in the Sun. The uncertainty on the accepted value of S(0) for this reaction is currently the largest important nuclear physics uncertainty (+/- 10%) in the Solar Model [1]. A more precise value of S34(0) would bring an improvement in solar neutrino flux calculations, and in predictions of 7Li production in Big-Bang Nucleosynthesis which are currently significantly higher than observed 7Li abundances [2].

Precision measurements of S34(E) have been made at eight different energies between Ec.m = 0.33 and 1.23 MeV, using the 9MV tandem Van-de-Graaff accelerator at the University of Washington. The prompt gamma-ray yield and the 7Be activity have been measured at each energy in the same irradiation, permitting two different methods for determining S34(E). This presentation discusses the experimental details of these measurements, the analysis of the data and our results for S34(0).

[1] E. G. Adelberger et al., Rev. Mod. Phys. 70 4 (1998) 1265
[2] P. Bonifacio et al., Astron. Astrophys. 390 (2002) 91

Stimulants available 15 minutes before the talk.

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