Radiative decays of the 16.6 and 16.9 MeV states in Be8 and tests of the conservation of the vector current in the A=8 multiplet

We measured the He4(α,γ) cross section at θγ= 90°across the 16.6 and 16.9 MeV resonances in Be8 and obtained angular distributions on the peaks of both resonances. The decays of the 16 MeV doublet to the 3.0 MeV 2+ final state have an (isovector E2)/(isovector M1) mixing ratio of (0.01±0.03), an (isoscalar E2)/(isovector M1) mixing ratio of (0.21±0.04), and an isovector M1 width of (2.80±0.18) eV. Our result for the isovector E2 strength disagrees markedly with previous work. We observe ground-state E2 decays of both members of the doublet. We use our results, plus existing Li8 and B8 β-decay data, to test the conservation of the vector current and to constrain the second-class induced-tensor form factor. Finally, we compare our results to shell-model calculations. © 1995 The American Physical Society.

Duke Scholars

Author Diane M Markoff Physics