Relative population of states in ²¹Mg 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 gamma-ray spectroscopy was utilized to study few-nucleon removal reactions from incoming beams of ²⁴Mg, ²⁵Al, and ²⁶Si projectiles to the same reaction product, ²¹Mg. New gamma-ray transitions and gamma -gamma coincidences in ²¹Mg were established using the CsI(Na) array CAESAR and the inclusive cross section for three-neutron removal from ²⁴Mg was measured. Significant differences in the relative population of states in ²¹Mg from ²⁵Al compared to ²⁶Si were observed and found to be correlated with the spins of the ²¹Mg 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.