Shell model study of backbending phenomena in Xe isotopes

Xe isotopes near mass Asimilar to130 region, which exhibit features of O(6) symmetry at low energy and the backbending at high spins, are studied in the shell model framework. The monopole and quadrupole pairing plus quadrupole-quadrupole interaction is employed as an effective interaction. As for single-particle levels, the 1d(3/2), 0h(11/2), 2s(1/2) orbitals are taken into account for neutrons and the 1d(5/2), 0g(7/2) orbitals for protons under the assumption of N=Z=64 subshell closure. The calculation reproduces the experimental energy levels of high-spin states as well as low-lying states well. This is the first successful microscopic description of the backbending in this mass region. The shell model states are examined in pair-truncated models. The analysis shows the alignment of two 0h(11/2) neutrons at high spins.