Using both the absolute and relative surrogate techniques, the {sup 236}U(n,f) cross section was deduced over an equivalent neutron energy range of 0 to 20 MeV. A 42 MeV {sup 3}He beam from the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory was used to perform a ({sup 3}He,{alpha}) pickup reaction on targets of {sup 235}U (J{sup {pi}}=7/2{sup -}) and {sup 238}U (J{sup {pi}}=0{sup +}) and the fission decay probabilities were determined. The {sup 235}U({sup 3}He,{alpha}f) and {sup 238}U({sup 3}He,{alpha}f) were surrogates for {sup 233}U(n,f) and {sup 236}U(n,f), respectively. The cross sections extracted using the Surrogate Method were compared to directly measured cross sections. The sensitivity of these cross sections to the J{sup {pi}}-population distributions was explored.

We examine the branching ratio of the N{sub 4,5} (4d {yields} 5f ) spectra of Th, U, Np, Pu, Am, and Cm metal using electron energy-loss spectroscopy (EELS) in a transmission electron microscope (TEM), together with many-electron atomic spectral calculations and the spin-orbit sum rule. Our results show that: (1) The actinide metals Pu, Am, and Cm exhibit intermediate coupling. (2) The intermediate coupling values for the 5f states as calculated using a many-electron atomic model are correct for the actinides, this being proven by our new results for curium. (3) The EELS branching ratio is sensitive to the degree of 5f electron delocalization, which is illustrated by the transition from LS to intermediate coupling between U and Pu.

Self-consistent Vlasov-Poisson simulations of beams with high space-charge intensity often require specification of initial phase-space distributions that reflect properties of a beam that is well adapted to the transport channel--both in terms of low-order rms (envelope) properties as well as the higher-order phase-space structure. Here, we first review broad classes of kinetic distributions commonly in use as initial Vlasov distributions in simulations of unbunched or weakly bunched beams with intense space-charge fields including: the Kapchinskij-Vladimirskij (KV) equilibrium, continuous-focusing equilibria with specific detailed examples, and various non-equilibrium distributions, such as the semi-Gaussian distribution and distributions formed from specified functions of linear-field Courant-Snyder invariants. Important practical details necessary to specify these distributions in terms of usual accelerator inputs are presented in a unified format. Building on this presentation, a new class of approximate initial kinetic distributions are constructed using transformations that preserve linear-focusing single-particle Courant-Snyder invariants to map initial continuous-focusing equilibrium distributions to a form more appropriate for non-continuous focusing channels. Self-consistent particle-in-cell simulations are employed to show that the approximate initial distributions generated in this manner are better adapted to the focusing channels for beams with high space-charge intensity. This improved capability enables simulation applications that more precisely probe intrinsic stability …

This report is a descriptive journey of 2006 Electrochemistry Gordon Research Conference.