Complete kinematical study of the 3α breakup of the 16.11 MeV state in 12C

Abstract

The reaction 11B + p has been used to populate the (Jπ,T) = (2+,1) state at an excitation energy of 16.11 MeV in 12C, and the breakup of the state into three α-particles has been studied in complete kinematics. A two-step breakup model which includes interference effects is found to provide the most accurate description of the experimental data. The branching ratio to the ground state of 8Be is determined to be 5.1(5)% in agreement with previous findings, but more precise by a factor of two, while the decay to the first excited state in 8Be is found to be dominated by d-wave emission.