Isospin and F-spin symmetry structure in low-lying levels of Cr-48,Cr-50 isotopes

The low-energy level structure and electromagnetic transitions of Cr-48,Cr-50 nuclei have been studied using the interacting boson model with isospin (IBM-3). A sequence of isospin excitation bands with isospin T = T-z, T-z + 1 and T-z + 2 has been assigned, and compared with available data. According to this study, the 2(3)(+) and 2(2)(+) states are the lowest mixed symmetry states in Cr-48 and Cr-50, respectively. In particular, the present calculations suggest that a combination of isospin and F-spin excitation can explain the structure in these nuclei. The transition probabilities between the levels are analysed in terms of isoscalar and isovector decompositions which reveal the detailed nature of the energy levels. The results obtained are in good agreement with recent experimental data.