Validity of spectator core model in neutron knock-out reactions

A few-body model for stripping reactions based on the Glauber approach is p resented, which goes beyond the usual spectator core' assumption. The model , which is applied to the one-neutron knockout reactions (Be-12,Be-11) and (C-16,C-15), assumes an incident three-body projectile (core-2n) with an ou tgoing two-body subsystem (core+n) and includes off-diagonal elements in th e transition matrix for the surviving fragment which couple different singl e particle states. Corrections of less that 10% to the stripping cross sect ions are found when these dynamical effects are included, implying that the spectator assumption is valid even when the spectator is itself a lossely- bound composite system.