Microscopic look at backbending

R. D.Ratna Raju, University of Michigan, Ann Arbor
K. T. Hecht, University of Michigan, Ann Arbor
B. D. Chang, Louisiana State University
J. P. Draayer, Louisiana State University


A shell-model calculation of high-spin phenomena in the highly neutron deficient Ba-Ce-Nd region is reported. An inert spherically symmetric Z=50=N core is assumed with extracore nucleons distributed among the g72, d52, d32, s12 normal-parity orbitals and the unique parity h112 orbital with the number of particles within each set fixed. The normal-parity subspace is further truncated to a single irreducible representation of pseudo SU(3) made effective through the mapping (g72d52d32s12)→(f72f52p32p12). A five-dimensional quasispin classification is used for the unique-parity h112 space which is restricted to states with seniority zero and two. Using a surface delta interaction we are able to reproduce the observed backbending in Ba7056126. The model affords a microscopic look at Coriolis antipairing and pair realignment phenomena. NUCLEAR STRUCTURE Ba56126; Shell-model interpretation of backbending, pair realignment, and Coriolis antipairing; h112; g72d52d32s12 configurations with pseudo-SU3 truncation. © 1979 The American Physical Society.