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.

Automated summary

Intermediate-energy nuclear reactions involving the removal of three, four, and five nucleons can proceed through nondissipative and statistical processes. In this experiment at the National Superconducting Cyclotron Laboratory, gamma-ray spectroscopy was used to study few-nucleon removal reactions from different projectile beams to the same reaction product. The results showed significant differences in the population of states in the reaction product, which were correlated with the spins of the states. This intermediate regime may have the potential to produce unique level populations in fast-beam experiments and alter isomer to ground state ratios.