Measurement of the 7Li(γ,t)4He ground-state cross section between Eγ = 4.4 and 10 MeV
M. Munch, C. Matei, S. D. Pain, et al., Phys. Rev. C 101, 055801
The 7Li(γ,t)4He ground state cross section was measured for the first time using monoenergetic γ rays with energies between 4.4 and 10 MeV at the High Intensity Gamma-ray Source. The reaction is important for the primordial Li problem and for testing our understanding of the mirror α-capture reactions 3H(α,γ)7Li and 3He(α,γ)7Be. Although over the last 30 years most measurements of the 3H(α,γ)7Li reaction have concentrated in an energy range below Eγ=3.65 MeV, measurements at higher energies could potentially restrict the extrapolation to astrophysically important energies. The experimental arrangement for measuring the 7Li(γ,t)4He reaction included a large-area silicon detector array and several beam characterization instruments. The experimental astrophysical S factor of 3H(α,γ) calculated from the present data was fitted using the R-matrix formalism. The results are in disagreement with previous experimental measurements in the same energy range but the extrapolated S factor agrees with the potential model calculation and lower energy experimental data.
