How Different is the Core of F25 from O

The neutron-shell structure of 25 F was studied using quasi-free (p,2p) knockout reaction at 270A MeV in inverse kinematics.The sum of spectroscopic factors of π0d 5/2 orbital is found to be 1.0 ± 0.3.However, the spectroscopic factor for the ground-state to ground-state transition ( 25 F, 24 O g.s. ) is only 0.36 ± 0.13, and 24 O excited states are produced from the 0d 5/2 proton knockout.The result shows that the 24 O core of 25 F nucleus significantly differs from a free 24 O nucleus, and the core consists of ∼35% 24 O g.s. and ∼65% excited 24 O.