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Calculation of 239Pu fission observables in an event-by-event simulation (open access)

Calculation of 239Pu fission observables in an event-by-event simulation

The increased interest in more exclusive fission observables has demanded more detailed models. We describe a new computational model, FREYA, that aims to meet this need by producing large samples of complete fission events from which any observable of interest can then be extracted consistently, including any interesting correlations. The various model assumptions are described and the potential utility of the model is illustrated. As a concrete example, we use formal statistical methods, experimental data on neutron production in neutron-induced fission of {sup 239}Pu, along with FREYA, to develop quantitative insights into the relation between reaction observables and detailed microscopic aspects of fission. Current measurements of the mean number of prompt neutrons emitted in fission taken together with less accurate current measurements for the prompt post-fission neutron energy spectrum, up to the threshold for multi-chance fission, place remarkably fine constraints on microscopic theories.
Date: March 31, 2010
Creator: Vogt, R; Randrup, J; Pruet, J & Younes, W
System: The UNT Digital Library
Developing the Next Generation of International Safeguards and Nonproliferation Experts: Highlights of Select Activities at the National Laboratories (open access)

Developing the Next Generation of International Safeguards and Nonproliferation Experts: Highlights of Select Activities at the National Laboratories

With many safeguards experts in the United States at or near retirement age, and with the growing and evolving mission of international safeguards, attracting and educating a new generation of safeguards experts is an important element of maintaining a credible and capable international safeguards system. The United States National Laboratories, with their rich experience in addressing the technical and policy challenges of international safeguards, are an important resource for attracting, educating, and training future safeguards experts. This presentation highlights some of the safeguards education and professional development activities underway at the National Laboratories. These include university outreach, summer courses, internships, mid-career transition, knowledge retention, and other projects. The presentation concludes with thoughts on the challenge of interdisciplinary education and the recruitment of individuals with the right balance of skills and backgrounds are recruited to meet tomorrow's needs.
Date: March 31, 2010
Creator: Reed, J.; Mathews, C.; Kirk, B.; Lynch, P.; Doyle, J.; Meek, E. et al.
System: The UNT Digital Library
Generalized Energy-Dependent Q Values for Fission (open access)

Generalized Energy-Dependent Q Values for Fission

We extend Madland's parameterization of the energy release in fission to obtain the dependence of the fission Q value for major and minor actinides on the incident neutron energies in the range 0 {le} E{sub n} {le} 20 MeV. Our parameterization is based on the actinide evaluations recommended for the ENDF/B-VII.1 release. This paper describes the calculation of energydependent fission Q values based on the calculation of the prompt energy release in fission by Madland. This calculation was adopted for use in the LLNL ENDL database and then generalized to obtain the prompt fission energy release for all actinides. Here the calculation is further generalized to the total energy release in fission. There are several stages in a fission event, depending on the time scale. Neutrons and gammas may be emitted at any time during the fission event.While our discussion here is focussed on compound nucleus creation by an incident neutron, similar parameterizations could be obtained for incident gammas or spontaneous fission.
Date: March 31, 2010
Creator: Vogt, R
System: The UNT Digital Library
In situ soft X-ray absorption spectroscopy investigation of electrochemical corrosion of copper in aqueous NaHCO3 solution (open access)

In situ soft X-ray absorption spectroscopy investigation of electrochemical corrosion of copper in aqueous NaHCO3 solution

A novel electrochemical setup has been developed for soft x-ray absorption studies of the electronic structure of electrode materials during electrochemical cycling. In this communication we illustrate the operation of the cell with a study of the corrosion behavior of copper in aqueous NaHCO3 solution via the electrochemically induced changes of its electronic structure. This development opens the way for in situ investigations of electrochemical processes, photovoltaics, batteries, fuel cells, water splitting, corrosion, electrodeposition, and a variety of important biological processes.
Date: March 31, 2010
Creator: Jiang, Peng; Chen, Jeng-Lung; Borondics, Ferenc; Glans, Per-Anders; West, Mark W.; Chang, Ching-Lin et al.
System: The UNT Digital Library
An investigation on the concrete properties containing colemanite (open access)

An investigation on the concrete properties containing colemanite

This article summarizes the results of an investigation on the effect of the colemanite on physical and mechanical properties of concrete using colemanite as replacement aggregate.
Date: March 31, 2010
Creator: Gencel, Osman; Brostow, Witold, 1934-; Ozel, Cengiz & Filiz, Mümin
System: The UNT Digital Library
REMOVAL OF CESIUM FROM SAVANNAH RIVER SITE WASTE WITH SPHERICAL RESORCINOL FORMALDEHYDE ION EXCHANGE RESIN EXPERIMENTAL TESTS (open access)

REMOVAL OF CESIUM FROM SAVANNAH RIVER SITE WASTE WITH SPHERICAL RESORCINOL FORMALDEHYDE ION EXCHANGE RESIN EXPERIMENTAL TESTS

A principal goal at the Savannah River Site (SRS) is to safely dispose of the large volume of liquid nuclear waste held in many storage tanks. In-tank ion exchange (IX) columns are being considered for cesium removal. The spherical form of resorcinol formaldehyde ion exchange resin (sRF) is being evaluated for decontamination of dissolved saltcake waste at SRS, which is generally lower in potassium and organic components than Hanford waste. The sRF performance with SRS waste was evaluated in two phases: resin batch contacts and IX column testing with both simulated and actual dissolved salt waste. The tests, equipment, and results are discussed.
Date: March 31, 2010
Creator: Duignan, M. & Nash, C.
System: The UNT Digital Library
ScalaTrace: Tracing, Analysis and Modeling of HPC Codes at Scale (open access)

ScalaTrace: Tracing, Analysis and Modeling of HPC Codes at Scale

Characterizing the communication behavior of large-scale applications is a difficult and costly task due to code/system complexity and their long execution times. An alternative to running actual codes is to gather their communication traces and then replay them, which facilitates application tuning and future procurements. While past approaches lacked lossless scalable trace collection, we contribute an approach that provides orders of magnitude smaller, if not near constant-size, communication traces regardless of the number of nodes while preserving structural information. We introduce intra- and inter-node compression techniques of MPI events, we develop a scheme to preserve time and causality of communication events, and we present results of our implementation for BlueGene/L. Given this novel capability, we discuss its impact on communication tuning and on trace extrapolation. To the best of our knowledge, such a concise representation of MPI traces in a scalable manner combined with time-preserving deterministic MPI call replay are without any precedence.
Date: March 31, 2010
Creator: Mueller, F; Wu, X; Schulz, M; de Supinski, B & Gamblin, T
System: The UNT Digital Library
Stability of modulation transfer function calibration of surface profilometers using binary pseudo-random gratings and arrays with nonideal groove shapes (open access)

Stability of modulation transfer function calibration of surface profilometers using binary pseudo-random gratings and arrays with nonideal groove shapes

The major problem of measurement of a power spectral density (PSD) distribution of surface heights with surface profilometers arises due to the unknown Modulation Transfer Function (MTF) of the instruments, which tends to distort the PSD at higher spatial frequencies. The special mathematical properties of binary pseudo-random patterns make them an ideal basis for developing MTF calibration test surfaces. Two-dimensional binary pseudo-random arrays (BPRAs) have been fabricated and used for the MTF calibration of the MicroMap{trademark}-570 interferometric microscope with all available objectives. An investigation into the effects of fabrication imperfections on the quality of the MTF calibration and a procedure for accounting for such imperfections are presented.
Date: March 31, 2010
Creator: Barber, Samuel K.; Anderson, Erik H.; Cambie, Rossana; Marchesini, Stefano; McKinney, Wayne R.; Takacs, Peter Z. et al.
System: The UNT Digital Library
Water adsorption, solvation and deliquescence of alkali halide thin films on SiO2 studied by ambient pressure X-ray photoelectron spectroscopy (open access)

Water adsorption, solvation and deliquescence of alkali halide thin films on SiO2 studied by ambient pressure X-ray photoelectron spectroscopy

The adsorption of water on KBr thin films evaporated onto SiO2 was investigated as a function of relative humidity (RH) by ambient pressure X-ray photoelectron spectroscopy. At 30percent RH adsorbed water reaches a coverage of approximately one monolayer. As the humidity continues to increase, the coverage of water remains constant or increases very slowly until 60percent RH, followed by a rapid increase up to 100percent RH. At low RH a significant number of the Br atoms are lost due to irradiation damage. With increasing humidity solvation increases ion mobility and gives rise to a partial recovery of the Br/K ratio. Above 60percent RH the increase of the Br/K ratio accelerates. Above the deliquescence point (85percent RH), the thickness of the water layer continues to increase and reaches more than three layers near saturation. The enhancement of the Br/K ratio at this stage is roughly a factor 2.3 on a 0.5 nm KBr film, indicating a strong preferential segregation of Br ions to the surface of the thin saline solution on SiO2.
Date: March 31, 2010
Creator: Arima, Kenta; Jiang, Peng; Deng, Xingyi; Bluhm, Henrik & Salmeron, Miquel
System: The UNT Digital Library