Observation of superdeformation in Hg191

The first observation of superdeformation in the mass region A190 is reported. A rotational band of twelve transitions with an average energy spacing of 37 keV, an average moment of inertia scrF(2) of 110 Latin small letter h with stroke2 MeV-1, and an average quadrupole moment of 183 e b has been observed in Hg191; this band persists at low rotational frequency. These results are in excellent agreement with a calculation that predicts an ellipsoidal axis ratio of 1.65:1 for the superdeformed shape in this nucleus

Nucleon alignment in 191Hg. A competing mechanism at moderate spins

Detailed spectroscopic studies of the discrete γ-rays feeding and deexciting a 41 2-, 4.6 MeV level in 191Hg are reported. The resulting decay scheme indicates single-particle nature for the states above the 41 2- level. At moderate spin, the corresponding particle alignment mode competes favorably with collective oblate rotation. It is suggested that this sequence is associated with a non-collective prolate shape (ε{lunate}=0.1-0.15, γ≅-120°)

Gamma ray studies of neutron-rich sdf shell nuclei produced in heavy ion collisions

Reanalysis of ichproductsofbinaryreactio nsof$34S, S36, and Cl37 beams on Gd160 targets. Gates set on known amma$raysin$A∼160 products selected individual react ion channels and identified coincident amma$raysin$A∼36 partner products. Transfers of protons from projectile to target and of neutrons from target to projectile were generally favored, leading to excited neutron-rich light nuclei, including some difficult to reach by other means. Notable results include the observation of amma$raycascadesupthehigh e stknownyraststatesinfour$N=20 isotones. In two N=19 nuclei, Si33 and P34, the two N=22 nuclei, S38 and Cl39, previously unknown yrast states were identified

Collectivity of dipole bands in Pb196

The lifetimes of states in two of the ΔI=1 bands in Pb196 have been measured using the Doppler shift attenuation method, and a new ΔI=1 band has been observed in this nucleus. States in the bands were populated in the reaction Er107(30Si,4n) at a beam energy of 142 MeV. Individual level lifetimes were extracted from the data by a analysis of the Doppler broadened γ-ray lineshapes. Under the assumption of pure M1 radiation, average reduced transition strengths B(M1)∼1.5 W.u. were obtained. The B(M1) values in both the ''regular'' and ''irregular'' bands exhibit similar dependence on spin. The neutron and proton configurations and nature of the collectivity in these bands is discussed

Spectroscopy of the superdeformed band in Pb196

The superdeformed band in Pb196 has been studied extensively using the reaction Er170(30Si,4n) at beam energies of 142, 146, and 151 MeV. New transitions have been added at the top and bottom of the previously known band. Gamma-ray directionsl correlations were measured for most of the transitions in the band verifying the expected stretched E2 character. The collectivity of the band has been measured using the Doppler shift attenuation method yielding an intrinsic quadrupole moment Q0 of 18.3±3.0 e b, in good agreement with theoretical predictions. The variations of the dynamic moment of inertia scrI(2) as a function of the rotational frequency Latin small letter h with strokeω have been studied and compared with cranked shell model calculations. The dependence of scrI(2) on mass for superdeformed bands in the Pb isotopes is also investigated

Yrast isomers in tin nuclei from heavy ion collisions and the νh_{11/2} subshell filling

none13Long-lived 10+ isomers in 122Sn and 124Sn have been identified among the products of 124Sn+325 MeV 76Ge collisions. The measurements virtually complete a series of B(E2) determinations for (νh11/2)n states in 116-130Sn, which pinpoint half filling of the νh11/2 subshell very close to N=73. Results for these Z=50 isotopes and for the N=82 isotones are contrasted, and an enlightening comparison between the effective E2 charges observec in tin and lead isotopes is developed.noneR. Broda;R. Mayer;I. Bearden;Ph. Benet;P. Daly;Z. Grabowski;M. Carpenter;R. Janssens;T. Khoo;T. Lauritsen;E. Moore;S. Lunardi;J. BlomqvistR., Broda; R., Mayer; I., Bearden; Benet, P. h.; P., Daly; Z., Grabowski; M., Carpenter; R., Janssens; T., Khoo; T., Lauritsen; E., Moore; Lunardi, Santo; J., Blomqvis

Spectroscopy of the superdeformed band in 196Pb

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Collectivity of Dipole Bands in 196Pb

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