Unbound states in $^{12}$C populated by $γ$-decay of the $(J^π,T) = (2^+,1)$ 16.11 MeV state

Abstract

The reaction $^{11}\textrm{B}+p$ has been used to populate the $(J^π,T) = (2^+,1)$ state at an excitation energy of 16.11 MeV in $^{12}$C. $γ$-decay to unbound states in $^{12}$C are identified from analysis of the decay of the populated daughter states. Due to a new technique, $γ$-decay to the 10.8 MeV 1$^-$ state is observed for the first time, and transitions to the 9.64 MeV (3$^-$) and 12.71 MeV (1$^+$) are confirmed. Unresolved transitions to natural parity strength at 10 MeV and 11.5-13 MeV are also observed. For all transitions partial widths are deduced

Corrected small typographical errors and added more details on data analysis