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Over the past three years we have studied various surrogate reactions (d,p), (3He,t), (α,α′) on several uranium isotopes 234U, 235U, 236U, and 238U. An overview of the STARS/LIBERACE surrogate research program as it pertains to the actinides is discussed. A summary of results to date will be presented along with a discussion of experimental difficulties encountered in surrogate experiments and future research directions. [ABSTRACT FROM AUTHOR]

Measurements of the excitation energies of superdeformed states via the observation of single-step linking transitions have now been made in three even-A Pb nuclei, with a quasicontinuum analysis providing a limit in a fourth, odd-A case. These results allow us to take the first steps towards establishing systematic trends in excitation energies and binding energies in the second minimum in Pb isotopes. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Coulomb excitation of Kπ=6+(t1/2=77 ns), 8-(t1/2=4.0 s) and 16+(t1/2=31 y) 178Hf isomers has led to the measurement of a set of Eλ matrix elements, coupling the isomer bands to the γ- and ground state bands. The resulting matrix elements, derived using a coupled-channel semiclassical Coulomb excitation search code, have been used to probe the K-components in the wave functions and revealed the onset and saturation of K-mixing in low-K bands, whereas K-mixing is negligible in the high-K bands. The implications can be applied to other quadrupole-deformed nuclei. An upper limit on the Coulomb depopulation yield of the 16+ isomer was calculated based on the present set of matrix elements. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The quasi-continuum of γ rays from the feeding and decay of superdeformed and normal bands in the nucleus 152Dy have been extracted in 1 - and 2 - dimensional spectra. The Eγ-Eγ correlations in the latter reveals strong ridges associated with superdeformed and normal states in this nucleus. The entry distributions for normal and superdeformed bands were also extracted. A Monte Carlo model was developed that simultaneously describes all the quasi-continuum and ridge spectra as well as the feeding intensity of the superdeformed bands. Through the calculation of the continuum of γ rays at finite temperature, the rotational damping widths in the normal and superdeformed wells were extracted. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The yrast superdeformed (SD) band in 84Zr has been linked to states of normal deformation (ND) by three single-step γ decays. The spins and parity of the SD band were determined through angular distributions of two of these links. The properties of this band and its decay to ND states are compared with linked SD bands in other mass regions. SD intensity profiles, calculated SD-ND potential barriers, and results of a statistical-decay analysis suggest there is significant SD-ND mixing involved. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

The heavy-ion radiative capture reaction, 12C(12C,γ), has been investigated at beam energies around 16 MeV. Three different experiments were performed. Capture cross-sections were obtained by measuring fused 24Mg residues using the FMA at ANL. These were found to significantly exceed values reported earlier. Subsequently, the decay pathways associated with radiative capture were studied in two separate measurements: one with the high-resolution Gammasphere array and a second with a high efficiency BGO array, where gamma rays were recorded in coincidence with 24Mg residues detected at the focal plane of the DRAGON recoil separator at TRIUMF. Both measurements indicate that a substantial fraction of the decay is mediated through high-lying doorway states, possibly associated with the long-predicted shape-isomeric band in 24Mg. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

Multinucleon transfer reactions between a thin 100Mo target and a 136Xe beam at an energy of 700 MeV have been used to investigate the evolution of structure with increasing angular momentum in a range of nuclei with A∼100. The use of kinematically complete experiments coupled with isomer tagging allow the selection of specific exit channels. The evolution from quasi-vibrational states at low spins to quasi-rotational structures following the population of a low-Ω, ‘rotationally aligned’ h11/2 neutron configuration is demonstrated to be a standard feature of the region using the so-called E-Gamma Over Spin (E-GOS) empirical prescription. This treatment is extended to odd-A nuclei. [ABSTRACT FROM AUTHOR]

We review the experimental data on binding energy differences for nuclei along the N=Z line and compare these results with calculations based on single l and single j shell models. In spite of their simplicity, these models incorporate the main ingredients of the np pairing correlations and provide a firm basis to support some general arguments that can be used to rule out the formation of a condensate of isoscalar np pairs. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We measured the ratio of the fission probabilities of 234U* relative to 236U* formed via an (α,α′) direct reactions using the STARS array at the 88-inch cyclotron at the Lawrence Berkeley National Laboratory. This ratio has a shape similar to the ratio of neutron capture probabilities from 233U(n,f) and 235U(n,f), indicating the alpha reactions likely formed a compound nucleus. This result indicates that the ratios of fission exit channel probabilities for two actinide nuclei populated via (α,α′) can be used to determine an unknown fission cross section relative to a known one. The validity of the External Surrogate Ratio Method (ESRM) is tested and the results support the conclusions of Burke et al. [1]. [ABSTRACT FROM AUTHOR]

High-spin states in the neutron-rich [SUP106,108,110, 111,112]Rh isotopes have been investigated in the fission of the compound system formed in three heavy-ion induced reactions. Four bands were assigned to [SUP106,108,110,112]Rh respectively. Comparison with the lighter odd-odd Rh isotopes supports the assignment of the bands to the π8 [SUB9/2] ⊗ vh[SUB11/2] configuration. In [SUP111]Rh the level scheme consists of two rotational bands. In the ground-state band the odd-proton occupies the πg 9/2 orbital. [ABSTRACT FROM AUTHOR]