The Advanced Photon Source (APS) injector linac has been reconfigured with a low-emittance rf thermionic gun and a photocathode (PC) rf gun to support self-amplified spontaneous emission (SASE) free-electron laser (FEL) experiments. One of the most critical parameters for optimizing SASE performance (gain length) is the electron beam peak current, which requires a charge measurement and a bunch length measurement capability. We report here initial measurements of the latter using both incoherent optical transition radiation (OTR) and coherent transition radiation (CTR), A visible light Hamarnatsu C5680 synchroscan streak camera was used to measure the thermionic rf gun beam's bunch length ({sigma} {approximately}2 to 3ps) via OTR generated by the beam at 220 MeV and 200 mA macropulse average current. In addition, a CTR monitor (Michelson Interferometer) based on a Golay cell as the far infrared (FIR) detector has been installed at the 40-MeV station in the beamline. Initial observation s of CTR signal strength variation with gun a-magnet current and interferograms have been obtained. Progress in characterizing the beam at these locations and a comparison to other bunch length determinations will be presented.

We describe the development and implementation of a spectral element code for multimillion gridpoint simulations of incompressible flows in general two- and three-dimensional domains. Parallel performance is present on up to 2048 nodes of the Intel ASCI-Red machine at Sandia.

Version 5A of the Integrated Market Penetration and Anticipated Cost of Transportation Technologies (IMPACTT5A) model is a spreadsheet-based set of algorithms that calculates the effects of advanced-technology vehicles on baseline fuel use and emissions. Outputs of this Argonne National Laboratory-developed model include estimates of (1) energy use and emissions attributable to conventional-technology vehicles under a baseline scenario and (2) energy use and emissions attributable to advanced- and conventional-technology vehicles under an alternative market-penetration scenario. Enhancements to IMPACIT made after its initial documentation in December 1994 have enabled it to deal with a wide range of fuel and propulsion system technologies included in Argonne's GREET model in a somewhat modified three-phased approach. Vehicle stocks are still projected in the largely unchanged STOCK module. Vehicle-miles traveled, fuel use, and oil displacement by advanced-technology vehicles are projected in an updated USAGE module. Now, both modules can incorporate vehicle efficiency and fuel share profiles consistent with those of the Partnership for a New Generation of Vehicles. Finally, fuel-cycle emissions of carbon monoxide, volatile organic compounds, nitrogen oxides, toxics, and greenhouse gases are computed in the EMISSIONS module via an interface with the GREET model that was developed specifically to perform such calculations. Because of …

In 1998, we reported the three-laboratory measurement of the {sup 44}Ti half-life which was determined relative to the well known value (5.2714 {+-} 0.0005 yr) of the {sup 60}Co half-life. We have continued the measurement at Argonne and Jerusalem and inclusion of data points for additional two years does not change our published value of 59.0 {+-} 0.6 yr.

To better understand the vortex dynamics of coherent structures in turbulent and transitional boundary layers, we consider direct numerical simulation of the interaction between a flat-plate-boundary-layer flow and an isolated hemispherical roughness element. Of principal interest is the evolution of hairpin vortices that form an interlacing pattern in the wake of the hemisphere, lift away from the wall, and are stretched by the shearing action of the boundary layer. Using animations of unsteady three-dimensional representations of this flow, produced by the vtk toolkit and enhanced to operate in a CAVE virtual environment, we identify and study several key features in the evolution of this complex vortex topology not previously observed in other visualization formats.

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