Monte Carlo methods are frequently used for neutron and radiation transport. These methods have several advantages, such as relative ease of programming and dealing with complex meshes. Disadvantages include long run times and statistical noise. Monte Carlo photon transport calculations also often suffer from inaccuracies in matter temperature due to the lack of implicitness. In this paper we discuss the Monte Carlo algorithm as it is applied to neutron and photon transport, detail the differences between neutron and photon Monte Carlo, and give an overview of the ways the numerical method has been modified to deal with issues that arise in photon Monte Carlo simulations.

General formulae for resistive-wall induced beam dilution are presented and then applied to the final beam delivery system of linear colliders. Criteria for the design of final beam delivery systems are discussed.

The authors report on the search for the rare decays B{sup +} {yields} D{sup (*)+} K{sub s}{sup 0} in approximately 226 million {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the PEp-II asymmetric-energy B factory at SLAC. They do not observe any significant signal and they set 90% confidence level upper limits on the branching fractions, {Beta}(B{sup +} {yields} D{sup +}K{sup 0}) < 0.5 x 10{sup -5} and {Beta}(B{sup +} {yields} D*{sup +} K{sup 0}) < 0.9 x 10{sup -5}.

The authors have shown that in the Linac Coherent Light Source (LCLS) undulator region, because of the high frequency content in the bunch shape, the energy variation induced by the resistive wall wake is much larger when the (proper) ac conductivity calculation is performed, than for the often-used dc calculation. Using a round copper beam pipe will result in a (relative) energy variation many times the Pierce parameter, implying that a large fraction of beam will not reach saturation. Our results suggest that this situation can be improved by, instead, choosing a flat, aluminum beam pipe.

We are developing an inexpensive compact accelerator system primarily intended for pulsed radiography. Design characteristics are an 8 MeV endpoint energy, 2 kA beam current, a cell gradient of approximately 3 MV/m (for an overall accelerator length is 2-3 m), and <$1/Volt capital costs. Such designs have been made possible with the development of high specific energy dielectrics (>10J/cm{sup 3}), specialized transmission line designs and multi-gap laser triggered low jitter (<1 ns) gas switches. In this geometry, the pulse forming lines, switches, and insulator/beam pipe are fully integrated within each cell to form a compact, stand-alone, stackable unit. We detail our research and modeling to date, recent high voltage test results, and the integration concept of the cells into a radiographic system.

We present test problems that can be used to check the hydrodynamic implementation in computer codes designed to model the implosion of a National Ignition Facility (NIF) capsule. The problems are simplified, yet one of them is three-dimensional. It consists of a nearly-spherical incompressible imploding shell subjected to an exponentially decaying pressure on its outer surface. We present a semi-analytic solution for the time-evolution of that shell with arbitrary small three-dimensional perturbations on its inner and outer surfaces. The perturbations on the shell surfaces are intended to model the imperfections that are created during capsule manufacturing.

We describe a concept where WDM and O-CDMA share a set of discrete wavelengths and components while using similar modulation formats. O-CDMA acts as a channel multiplier. Experiments show the feasibility of >2X channel multiplication.

Simulations of the interactions of injected fluids with minerals within an engineered fracture in a sample of Desert Peak quartz monzonite were compared with experimental observations of fluid chemistry and fracture permeability. The observed decrease in permeability and effective hydraulic aperture was much more rapid ({approx}1.0 {micro}m/day) for a core injected with a mixed salt solution containing dissolved silica (near-saturation injectate), compared to cores injected with NaCl (far-from-saturation injectate) ({approx}0.1 {micro}m/day). Simulations were in qualitative agreement with these observations. Near-saturation injectate is predicted to result in net precipitation of secondary phases in the fracture ({approx}0.12 {micro}m/day), compared to a net dissolution of the rock for the far-from-saturation injectate ({approx}0.3 {micro}m/day). Permeability loss for the near-saturation-injectate is ascribed to precipitation in the fracture as well as potential dissolution of primary mineral asperities. Permeability loss for the far-from-saturation fluid is ascribed to dissolution of asperities and smoothing of the fracture. Post-test analysis of the fracture surface will be necessary to verify the processes occurring. The simplified geochemical models used do not account for mineral heterogeneity or for distributions of fluid residence times which could be important controls on permeability evolution. Further analysis is planned to explicitly account for these phenomena.

Article about a combined birthday party for Donaji Lira and Lance Avery Morgan held in Austin, Texas.