THE T(α,γ)Li7 REACTION

Abstract

The T(α,γ)Li⁷ reaction has been observed using thin targets of tritium absorbed in zirconium bombarded by singly charged helium ions of energy from 0.5 Mev to 1.9 Mev. The cross section rises smoothly with energy in a fashion characteristic of a direct radiative capture process. The ratio of the intensities of transitions to the first excited state at 478 kev and to the ground state is 0.40 ± 0.05. The angular distribution is, to within errors, isotropic at E_α = 0.8 Mev but is significantly higher at 0° than at 90° for E_α = 1.6 Mev. The total capture cross section at a mean alpha-particle energy in the target of 1.32 Mev is 3.58 ± 0.60 microbarns and the corresponding astrophysical S factor is 0.064 ± 0.016 kev barn in the center of mass system. The results are compared with recent theoretical results on the direct radiative capture process.