A new determination of the partial widths of the 16.11 MeV state in 12C

The partial widths of the second T = 1 state of 12 C, at 16.11 MeV excitation energy, have been determined by measuring the 11 B(p, γ) and 11 B(p, α) cross sections at the E p = 163 keV resonance corresponding to this state. These measurements result in the new values of Γ p = 21.7 ± 1.8 eV and Γ γ = 21.6 ± 3.3 eV, for the partial widths of this state; approximately 3 times smaller and larger, respectively, than the present values in the literature. The new result for the proton width eliminates a serious discrepancy found in an earlier comparison of the partial widths of the T = 1 analogue states of the A = 12 system. Measurements were also made of the 11 B(d, n) 12 C ∗ reaction to compare the proton widths of the 15.11 and 16.11 MeV T = 1 states; these measurements confirm the new, smaller proton width for the 16.11 MeV state. An attempt was also made to determine the γ-width of the 16.11 MeV state by measuring the γ-branching ratio in the 10 B( 3 He, p) 12 C ∗ (γ) 12 C reaction.