A highly deformed band in 136Pm and the anomalous h11/2 proton crossing in the A ∼ 135 superdeformed region

The dynamical moments of inertia (J(2)) of superdeformed (SD) bands in the A∼150 Gd-Dy and A∼190 Hg-Pb regions are fairly well reproduced by standard cranking calculations. However, for the super or highly deformed A-135 Ce-Nd-Sm region, this is not true at all, and has presented a theoretical puzzle for some time. Several theoretical open-quote fixesclose quotes and suggestions in terms of quenched proton pairing and a strong residual proton-neutron interaction have been proposed. We have performed several experiments on the odd-odd nucleus 136Pm to help shed light on this problem. The first took place at the Holifield Heavy Ion Research Facility at Oak Ridge and used the 106Pd(34S,p3n) reaction at 165 MeV. High resolution γ-ray information was collected using 18 Compton suppressed Ge detectors which replaced elements within the Spin Spectrometer. Total energy and fold information was recorded by the remaining 52 NaI elements of the Spin Spectrometer. In addition, because charged particle emission competes on an equal footing with neutron evaporation in this mass region, the Washington University Dwarf Ball was used to detect the charged particles in coincidence with γ-rays. Another experiment was performed at Florida State University using the Superconducting Linear Accelerator Facility and the 108Pd(32S,p3n) reaction at 145 MeV. Gamma-rays were detected by the Pittsburgh-FSU array consisting of 9 Compton suppressed Ge detectors plus a 28 element bismuth germanate (BGO) sum energy/multiplicity ball. In both experiments a rotational band has been observed in 136Pm possessing an enhanced moment of inertia consistent with other highly deformed structures in this region