Yrast Structure of neutron-rich N=31,32 Titanium Nuclei- Subshell Closure at N=32

Gamma rays from neutron-rich Ti nuclei in the vicinity of N = 32 have been studied at Gammasphere using deep-inelastic reactions induced by a 305 MeV Ca-48 beam on a thick Pb-208 target. The yrast gamma-ray cascades in Ti-53 were identified for the first time and the location in energy of the states with spin up to J=21/2 was determined. The yrast excitations of Ti-53, together with the earlier studied yrast structure of Ti-54, provided new tests of effective interactions for full pf-shell calculations. The data confirm the presence of a significant subshell gap at N=32. Comparisons between theory and experiment regarding the highest spin states located in Ti-53,Ti-54 suggest that energy gap at N=34 in neutron-rich nuclei is not as large as predicted by the recently proposed GXPF1 interaction.