Complete kinematical study of the 3$\alpha$ breakup of the 16.11 MeV state in $^{12}$C

TL;DR

This study investigates the complete kinematics of the 3-alpha breakup of the 16.11 MeV state in carbon-12, providing detailed insights into the reaction mechanisms and decay pathways with improved precision.

Contribution

It introduces a comprehensive two-step breakup model including interference effects, offering a more accurate description of the 3-alpha breakup process in $^{12}$C.

Findings

Branching ratio to ground state of $^8$Be is 5.1(5)%

Decay to first-excited state in $^8$Be is dominated by d-wave emission

Model accurately describes experimental data

Abstract

The reaction $^{11}B+p$ has been used to populate the $(J^{\pi},T)=(2^+,1)$ state at an excitation energy of 16.11 MeV in $^{12}$C, and the breakup of the state into three $\alpha$ 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 $^8$Be 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 $^8$Be is found to be dominated by $d$-wave emission.