One- and two-neutron removal cross sections of 24 O

Cross sections of one- and two-neutron removal reactions of 24 O, leading to the 23 O(½ + ) ground state and to bound final states of 22 O, have been measured at the National Superconducting Cyclotron Laboratory. The experiment was conducted using the S800 spectrograph and a 24 O beam energy of 92.3 MeV/u. The measured 23 O ground state and 22 O inclusive cross section values, of 74(11) mb and 146(33) mb, respectively, are in good agreement with calculations using eikonal reaction dynamics and shell-model nuclear structure overlaps. The widths at half maximum of the associated parallel momentum distributions of these cross sections, deduced from Gaussian fits, are 115(13) MeV/c for 23 O and 309(36) MeV/c for 22 O in the projectile rest frame. The data and calculations strongly support the shell-model description of 24 O as a spherical, doubly-magic structure.