Structure of 55Ti and 49Ca from relativistic one-neutron knockout

Results are presented from a one-neutron knockout reaction at relativistic energies on 50Ca and 56Ti using the GSI FRS as a two-stage magnetic spectrometer and the Miniball array for gamma-ray detection. Inclusive and exclusive longitudinal momentum distributions and cross-sections were measured enabling the determination of the orbital angular momentum of the populated states. First-time observation of the 3.35(15) MeV nu f7/2-hole state in 49Ca and the 955(6) keV nu p3/2-hole state in 55Ti is reported. The measured data clearly indicates that the ground state of 55Ti is a 1/2- state, in agreement with shell-model calculations using the GXPF1A interaction that predict a sizable N=34 gap in 54Ca.