Reduced transition probabilities to the first 2+ state in 52,54,56Ti and development of shell closures at N=32,34 -: art. no. 041302

The even Ti52-56 isotopes have been studied with intermediate-energy Coulomb excitation and absolute B(E2;0(+)-> 2(1)(+)) transition rates have been obtained. These data confirm the presence of a subshell closure at neutron number N=32 in neutron-rich nuclei above the doubly magic nucleus Ca-48 and provide no direct evidence for the predicted N=34 closure. Large-scale shell model calculations with the most recent effective interactions are unable to reproduce the magnitude of the measured strengths in the semimagic Ti nuclei and their strong variation with neutron number.