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

TL;DR

This study investigates gamma decay pathways from an excited state in carbon-12, revealing new decay modes and providing detailed measurements of transition widths using a novel detection technique.

Contribution

It introduces a new method to observe gamma decay to unbound states in $^{12}$C, including the first observation of decay to the 10.8 MeV state.

Findings

First observation of gamma decay to the 10.8 MeV state in $^{12}$C.

Confirmation of transitions to 9.64 MeV and 12.71 MeV states.

Partial widths for all observed transitions are determined.

Abstract

The reaction $^{11}\textrm{B}+p$ has been used to populate the $(J^\pi,T) = (2^+,1)$ state at an excitation energy of 16.11 MeV in $^{12}$C. $\gamma$-decay to unbound states in $^{12}$C are identified from analysis of the decay of the populated daughter states. Due to a new technique, $\gamma$-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