The effect of the one-body Hamiltonian on the statistical fluctuations of the nuclear energy spectrum in 138Ba using the context of the nuclear shell model

The effect of the one-body Hamiltonian on the statistical fluctuations of the nuclear energy spectrum in 138 Ba is examined via the framework of the nuclear shell model, using an effective interaction of N82K for six valence protons in the N82-model space with a 132 Sn core. The level density for considered class of states is seen to have a Gaussian shape. The spectral fluctuations (i.e., the nearest-neighbors level spacing distribution and the Δ 3 statistic) formed with normal value of single-particle energies are well described by the Gaussian orthogonal ensemble of random matrices. An obvious quantum sign of breaking the chaoticity is seen with doubling the value of single-particle energies.