Abstrakt
Te and Xe isotopes above the N = 82 shell closure are investigated within a large-scale shell model approach based on an iterative matrix diagonalization algorithm. The spectra and transition strengths, computed using a realistic Hamiltonian, are in overall agreement with the available experimental data.
The calculation predicts an increasing neutron weight in the lowest collective 2(1)(+) state of the isotopes as they depart from the doubly magic Sn-132 and move toward the neutron drip line. Such a neutron dominance is predicted to cause a breaking of the neutron-proton exchange symmetry and a dramatic drop of the strengths of the E2 and M1 transitions among the excited 2(+) states.
This drop establishes a strong asymmetry between Te and Xe isotopes above and below the N = 82 shell closure.