Gamma-ray measurements in the one-neutron knockout of 17C, 19N, 21O and 25F

One-neutron knockout reactions in a 9Be target have been investigated at relativistic energies, near 700 MeV/u, for a set of sd-shell, neutron-rich nuclei. The experiment was performed in the FRS spectrometer, at GSI. γ-ray measurements were carried out by means of the MINIBALL γ-ray spectrometer and allowed the determination of partial cross-sections and branching ratios corresponding to the final states of the emerging knockout fragments. Experimental results are presented for 17C, 19N, 21O and 25F projectiles. The role of excited states of the N − 1 fragments in the composition of the ground state of these neutron-rich projectilesis outlined in this work.