Relative population of states in Mg21 from few-nucleon removal reactions

Nuclear reactions with intermediate-energy beams in which three, four, and five nucleons are removed are expected to proceed through a combination of nondissipative and statistical processes. In an experiment at the National Superconducting Cyclotron Laboratory, in-beam $\ensuremath{\gamma}$-ray spectroscopy was utilized to study few-nucleon removal reactions from incoming beams of $^{24}\mathrm{Mg}, ^{25}\mathrm{Al}$, and $^{26}\mathrm{Si}$ projectiles to the same reaction product, $^{21}\mathrm{Mg}$. New $\ensuremath{\gamma}$-ray transitions and $\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}$ coincidences in $^{21}\mathrm{Mg}$ were established using the CsI(Na) array CAESAR and the inclusive cross section for three-neutron removal from $^{24}\mathrm{Mg}$ was measured. Significant differences in the relative population of states in $^{21}\mathrm{Mg}$ from $^{25}\mathrm{Al}$ compared to $^{26}\mathrm{Si}$ were observed and found to be correlated with the spins of the $^{21}\mathrm{Mg}$ states. As a result, this intermediate regime between direct and statistical nucleon removal may have potential as a tool to deliver unique patterns of level populations in fast-beam experiments and alter isomer to ground state ratios in the production of exotic beams.