The goal of this work was to determine the effects on plutonium isotopic analysis of having plutonium inside of a 0.25 inch thick stainless steel can. To do this, they analyzed plutonium samples with a U-Pu InSpector (which uses a high-resolution gamma-ray detector and the analysis code MGA (Multi Group Analysis)), to determine both the 240-Pu/239-Pu ratio and the years since the plutonium was separated from americium. They analyzed a 1.6 kg plutonium sample that was placed inside of a 0.25 inch can at varying distances (0-2 meters) and count times (10 seconds-30 minutes). In separate experiments, they analyzed 0.4g plutonium sources with stainless-steel thickness' ranging from 0.125 to 1.0 inch. This report will show three effects of having plutonium in a stainless steel can: (1) 240-Pu/240-Pu can be quickly and accurately determined for a 1.6 kg plutonium sample inside of a 0.25 inch thick stainless-steel can, as this thickness of stainless steel acts as a perfect filter to reduce the intense 59 keV gamma peak from 241-Am. (2) The accuracy of determining the plutonium-americium separation date is not effected by 0.25 inch of stainless steel. (3) Both 240-Pu/239-Pu and the americium separation date can be accurately determined for stainless-steel …

{sup 207}Bi (t{sub 1/2}=32.2 y) was generated by activation of weapons material during a few ''clean'' nuclear tests at the U.S. Western Pacific Proving Grounds of Enewetak and Bikini Atolls. The radionuclides first appeared in the Enewetak environment during 1958 and in the environment of Bikini during 1956. Crater sediments from Bikini with high levels of {sup 207}Bi were analyzed by gamma spectrometry in an attempt to determine the relative concentrations of {sup 208}Bi (t{sup 1/2} = 3.68 x 10{sup 5} y). The bismuth isotopes were probably generated during the ''clean'', 9.3 Mt Poplar test held on 7/12/58. The atom ratio of {sup 208}Bi to {sup 207}Bi (R value) ranges from {approx}12 to over 200 in sections of core sediments from the largest nuclear crater at Bikini atoll. The presence of bismuth in the device is suggested to account for R values in excess of 10.

Because of their strong internal bonding, S-decorated Cu trimers are a likely agent of S-enhanced Cu transport between islands on Cu(111). According to ab-initio calculations, excellent healing of dangling Cu valence results in an ad-Cu{sub 3}S{sub 3} formation energy of only {approximately}0.28 eV, compared to 0.79 eV for a self-adsorbed Cu atom, and a diffusion barrier {le}0.35 eV.

SNLO is public domain software developed at Sandia National Laboratories. It is intended to assist in the selection of the best nonlinear crystal for a particular application, and in predicting its performance. This paper briefly describes its functions and how to use them.

Molecular dynamics (MD) simulations for three separately parameterized embedded atom methods (EAM) function sets are used to determine the liquid/vapor surface tension {gamma} for Al, Ni, Cu, Ag, and Au. The three EAM models differ in both the functional forms employed and the fitting procedure used. All the EAM potentials underestimate {gamma} but one of the models performs consistently better than the others. The authors show that including a correction to the local charge density associated with gradients in the density together with exploiting the invariance of the EAM bulk potential to appropriate transformations in the charge density can lead to improved values for {gamma}, as well as for solid free surface energies, within existing EAM function sets.

{sup 1}H NMR studies of the protonation of highly nonplanar porphyrins with strong acids reveal the presence of the previously elusive monocation, and show that its stability can be related to the amount of saddle distortion induced by protonation; the amount of saddle distortion for a porphyrin dication is also found to correlate well with the rate of intermolecular proton transfer.

The authors examine pair mass dependence near threshold as a means to measure the spin of the top quark in hadron collisions, and they discuss the possibility that a top quark signal could be hidden among the top events.

A scalable, distributed modeling and simulation framework has been developed at Argonne National Laboratory to study Intelligent Transportation Systems. The framework can run on a single-processor workstation, or run distributed on a multiprocessor computer or network of workstations. The framework is modular and supports plug-in models, hardware, and live data sources. The initial set of models currently includes road network and traffic flow, probe and smart vehicles, traffic management centers, communications between vehicles and centers, in-vehicle navigation systems, roadway traffic advisories. The modeling and simulation capability has been used to examine proposed ITS concepts. Results are presented from modeling scenarios from the Advanced Driver and Vehicle Advisory Navigation Concept (ADVANCE) experimental program to demonstrate how the framework can be used to evaluate the benefits of ITS and to plan future ITS operational tests and deployment initiatives.