Topics in the Physics of Particle Accelerators (open access)

Topics in the Physics of Particle Accelerators

High energy physics, perhaps more than any other branch of science, is driven by technology. It is not the development of theory, or consideration of what measurements to make, which are the driving elements in our science. Rather it is the development of new technology which is the pacing item. Thus it is the development of new techniques, new computers, and new materials which allows one to develop new detectors and new particle-handling devices. It is the latter, the accelerators, which are at the heart of the science. Without particle accelerators there would be, essentially, no high energy physics. In fact. the advances in high energy physics can be directly tied to the advances in particle accelerators. Looking terribly briefly, and restricting one's self to recent history, the Bevatron made possible the discovery of the anti-proton and many of the resonances, on the AGS was found the {mu}-neutrino, the J-particle and time reversal non-invariance, on Spear was found the {psi}-particle, and, within the last year the Z{sub 0} and W{sup {+-}} were seen on the CERN SPS p-{bar p} collider. Of course one could, and should, go on in much more detail with this survey, but I think there is …
Date: July 1, 1984
Creator: Sessler, Andrew M.
System: The UNT Digital Library
Opportunities for Saving Energy and Improving Air Quality in Urban Heat Islands (open access)

Opportunities for Saving Energy and Improving Air Quality in Urban Heat Islands

World energy use is the main contributor to atmospheric CO2. In 2002, about 7.0 giga metric tons of carbon (GtC) were emitted internationally by combustion of gas, liquid, and solid fuels (CDIAC, 2006), 2 to 5 times the amount contributed by deforestation (Brown et al., 1988). The share of atmospheric carbon emissions for the United States from fossil fuel combustion was 1.6 GtC. Increasing use of fossil fuel and deforestation together have raised atmospheric CO{sub 2} concentration some 25% over the last 150 years. According to global climate models and preliminary measurements, these changes in the composition of the atmosphere have already begun raising the Earth's average temperature. If current energy trends continue, these changes could drastically alter the Earth's temperature, with unknown but potentially catastrophic physical and political consequences. During the last three decades, increased energy awareness has led to conservation efforts and leveling of energy consumption in the industrialized countries. An important byproduct of this reduced energy use is the lowering of CO{sub 2} emissions. Of all electricity generated in the United States, about one-sixth is used to air-condition buildings. The air-conditioning use is about 400 tera-watt-hours (TWh), equivalent to about 80 million metric tons of carbon (MtC) …
Date: July 1, 2007
Creator: Akbari, Hashem
System: The UNT Digital Library
Laser Fusion: The First Ten Years 1962-1972 (open access)

Laser Fusion: The First Ten Years 1962-1972

This account of the beginning of the program on laser fusion at Livermore in 1962, and its subsequent development during the decade ending in 1972, was originally prepared as a contribution to the January 1991 symposium 'Achievements in Physics' honoring Professor Keith Brueckner upon his retirement from the University of San Diego at La Jolla. It is a personal recollection of work at Livermore from my vantage point as its scientific leader, and of events elsewhere that I thought significant. This period was one of rapid growth in which the technology of high-power short-pulse lasers needed to drive the implosion of thermonuclear fuel to the temperature and density needed for ignition was developed, and in which the physics of the interaction of intense light with plasmas was explored both theoretically and experimentally.
Date: July 6, 2006
Creator: Kidder, R. E.
System: The UNT Digital Library
Potential energy sputtering of EUVL materials (open access)

Potential energy sputtering of EUVL materials

Of the many candidates employed for understanding the erosion of critical Extreme Ultraviolet Lithography (EUVL) components, potential energy damage remains relatively uninvestigated. Unlike the familiar kinetic energy sputtering, which is a consequence of the momentum transferred by an ion to atoms in the target, potential energy sputtering occurs when an ion rapidly collects charge from the target as it neutralizes. Since the neutralization energy of a singly charged ion is typically on the order of 10 eV, potential energy effects are generally neglected for low charge state ions, and hence the bulk of the sputtering literature. As an ion's charge state is increased, the potential energy (PE) increases rapidly, e.g. PE(Xe{sup 1+})= 11 eV, PE(Xe{sup 10+}) = 810 eV, PE(Xe{sup 20+}) = 4.6 keV, etc. By comparison, the binding energy of a single atom on a surface is typically about 5 eV, so even relatively inefficient energy transfer mechanisms can lead to large quantities of material being removed, e.g. 25% efficiency for Xe{sup 10+} corresponds to {approx} 40 atoms/ion. By comparison, singly charged xenon ions with {approx} 20 keV of kinetic energy sputter only about 5 atoms/ion at normal incidence, and less than 1 atom/ion at typical EUV source energies. …
Date: July 2, 2004
Creator: Pomeroy, J. M.; Ratliff, L. P.; Gillaspy, J. D. & Bajt, S.
System: The UNT Digital Library
New Acceleration Methods (open access)

New Acceleration Methods

But a glance at the Livingston chart, Fig. 1, of accelerator particle energy as a function of time shows that the energy has steadily, exponentially, increased. Equally significant is the fact that this increase is the envelope of diverse technologies. If one is to stay on, or even near, the Livingston curve in future years then new acceleration techniques need to be developed. What are the new acceleration methods? In these two lectures I would like to sketch some of these new ideas. I am well aware that they will probably not result in high energy accelerators within this or the next decade, but conversely, it is likely that these ideas will form the basis for the accelerators of the next century. Anyway, the ideas are stimulating and suffice to show that accelerator physicists are not just 'engineers', but genuine scientists deserving to be welcomed into the company of high energy physicists. I believe that outsiders will find this field surprisingly fertile and, certainly fun. To put it more personally, I very much enjoy working in this field and lecturing on it. There are a number of review articles which should be consulted for references to the original literature. In …
Date: July 1, 1984
Creator: Sessler, Andrew M.
System: The UNT Digital Library
Chapter 9: Model Systems for Formation and Dissolution of Calcium Phosphate Minerals (open access)

Chapter 9: Model Systems for Formation and Dissolution of Calcium Phosphate Minerals

Calcium phosphates are the mineral component of bones and teeth. As such there is great interest in understanding the physical mechanisms that underlie their growth, dissolution, and phase stability. Control is often achieved at the cellular level by the manipulation of solution states and the use of crystal growth modulators such as peptides or other organic molecules. This chapter begins with a discussion of solution speciation in body fluids and relates this to important crystal growth parameters such as the supersaturation, pH, ionic strength and the ratio of calcium to phosphate activities. We then discuss the use of scanning probe microscopy as a tool to measure surface kinetics of mineral surfaces evolving in simplified solutions. The two primary themes that we will touch on are the use of microenvironments that temporally evolve the solution state to control growth and dissolution; and the use of various growth modifiers that interact with the solution species or with mineral surfaces to shift growth away from the lowest energy facetted forms. The study of synthetic minerals in simplified solution lays the foundation for understand mineralization process in more complex environments found in the body.
Date: July 29, 2006
Creator: Orme, C. A. & Giocondi, J. L.
System: The UNT Digital Library
Signaling to the P53 Tumor Suppressor Through Pathways Activated by Genotoxic and Non-Genotoxic Stresses. (open access)

Signaling to the P53 Tumor Suppressor Through Pathways Activated by Genotoxic and Non-Genotoxic Stresses.

The p53 tumor suppressor is a tetrameric transcription factor that is post-translational modified at {approx}18 different sites by phosphorylation, acetylation, or sumoylation in response to various cellular stress conditions. Specific posttranslational modifications, or groups of modifications, that result from the activation of different stress-induced signaling pathways are thought to modulate p53 activity to regulate cell fate by inducing cell cycle arrest, apoptosis, or cellular senescence. Here we review the posttranslational modifications to p53 and the pathways that produce them in response to both genotoxic and non-genotoxic stresses.
Date: July 1, 2002
Creator: Anderson, C. W. & Appella, E.
System: The UNT Digital Library
Metabolic engineering of E.coli for the production of a precursor to artemisinin, an anti-malarial drug (open access)

Metabolic engineering of E.coli for the production of a precursor to artemisinin, an anti-malarial drug

This document is Chapter 25 in the Manual of Industrial Microbiology and Biotechnology, 3rd edition. Topics covered include: Incorporation of Amorpha-4,11-Diene Biosynthetic Pathway into E. coli; Amorpha-4,11-Diene Pathway Optimization; "-Omics" Analyses for Increased Amorpha-4,11-Diene Production; Biosynthetic Oxidation of Amorpha-4,11-Diene.
Date: July 18, 2011
Creator: Petzold, Christopher & Keasling, Jay
System: The UNT Digital Library
Thermal neutron imaging in an active interrogation environment (open access)

Thermal neutron imaging in an active interrogation environment

Gain an in-depth understanding of the role of quark flavor.
Date: July 3, 2009
Creator: Jaffe, D. E.; Marciano, W.; Soni, A.; Parsa, Z. & Van de Water,R.
System: The UNT Digital Library
Storage and turnover of organic matter in soil (open access)

Storage and turnover of organic matter in soil

Historically, attention on soil organic matter (SOM) has focused on the central role that it plays in ecosystem fertility and soil properties, but in the past two decades the role of soil organic carbon in moderating atmospheric CO{sub 2} concentrations has emerged as a critical research area. This chapter will focus on the storage and turnover of natural organic matter in soil (SOM), in the context of the global carbon cycle. Organic matter in soils is the largest carbon reservoir in rapid exchange with atmospheric CO{sub 2}, and is thus important as a potential source and sink of greenhouse gases over time scales of human concern (Fischlin and Gyalistras 1997). SOM is also an important human resource under active management in agricultural and range lands worldwide. Questions driving present research on the soil C cycle include: Are soils now acting as a net source or sink of carbon to the atmosphere? What role will soils play as a natural modulator or amplifier of climatic warming? How is C stabilized and sequestered, and what are effective management techniques to foster these processes? Answering these questions will require a mechanistic understanding of how and where C is stored in soils. The quantity …
Date: July 15, 2008
Creator: Torn, M.S.; Swanston, C.W.; Castanha, C. & Trumbore, S.E.
System: The UNT Digital Library
Comparative assessment of status and opportunities for carbon Dioxide Capture and storage and Radioactive Waste Disposal In North America (open access)

Comparative assessment of status and opportunities for carbon Dioxide Capture and storage and Radioactive Waste Disposal In North America

Aside from the target storage regions being underground, geologic carbon sequestration (GCS) and radioactive waste disposal (RWD) share little in common in North America. The large volume of carbon dioxide (CO{sub 2}) needed to be sequestered along with its relatively benign health effects present a sharp contrast to the limited volumes and hazardous nature of high-level radioactive waste (RW). There is well-documented capacity in North America for 100 years or more of sequestration of CO{sub 2} from coal-fired power plants. Aside from economics, the challenges of GCS include lack of fully established legal and regulatory framework for ownership of injected CO{sub 2}, the need for an expanded pipeline infrastructure, and public acceptance of the technology. As for RW, the USA had proposed the unsaturated tuffs of Yucca Mountain, Nevada, as the region's first high-level RWD site before removing it from consideration in early 2009. The Canadian RW program is currently evolving with options that range from geologic disposal to both decentralized and centralized permanent storage in surface facilities. Both the USA and Canada have established legal and regulatory frameworks for RWD. The most challenging technical issue for RWD is the need to predict repository performance on extremely long time scales …
Date: July 22, 2011
Creator: Oldenburg, C. & Birkholzer, J.T.
System: The UNT Digital Library
To Know Ourselves (open access)

To Know Ourselves

An overview of the underlying science of the Human Genome Project
Date: July 1, 1996
Creator: Vaughan, Douglas
System: The UNT Digital Library
TRITIUM UNCERTAINTY ANALYSIS FOR SURFACE WATER SAMPLES AT THE SAVANNAH RIVER SITE (open access)

TRITIUM UNCERTAINTY ANALYSIS FOR SURFACE WATER SAMPLES AT THE SAVANNAH RIVER SITE

Radiochemical analyses of surface water samples, in the framework of Environmental Monitoring, have associated uncertainties for the radioisotopic results reported. These uncertainty analyses pertain to the tritium results from surface water samples collected at five locations on the Savannah River near the U.S. Department of Energy's Savannah River Site (SRS). Uncertainties can result from the field-sampling routine, can be incurred during transport due to the physical properties of the sample, from equipment limitations, and from the measurement instrumentation used. The uncertainty reported by the SRS in their Annual Site Environmental Report currently considers only the counting uncertainty in the measurements, which is the standard reporting protocol for radioanalytical chemistry results. The focus of this work is to provide an overview of all uncertainty components associated with SRS tritium measurements, estimate the total uncertainty according to ISO 17025, and to propose additional experiments to verify some of the estimated uncertainties. The main uncertainty components discovered and investigated in this paper are tritium absorption or desorption in the sample container, HTO/H{sub 2}O isotopic effect during distillation, pipette volume, and tritium standard uncertainty. The goal is to quantify these uncertainties and to establish a combined uncertainty in order to increase the scientific depth …
Date: July 31, 2012
Creator: Atkinson, R.
System: The UNT Digital Library
Extended Community: An Oral History of the Community Environmental Monitoring Program (CEMP), 1989 - 2003 (open access)

Extended Community: An Oral History of the Community Environmental Monitoring Program (CEMP), 1989 - 2003

Studying the Community Environmental Monitoring Program (CEMP) provides a unique opportunity to trace a concept created by two nuclear industry originators from inception, as it transitioned through several stewardship agencies, to management by a non-profit organization. This transition is informed not only by changes over two decades in the views of the general populace toward nuclear testing but also by changing political climates and public policies. Several parallel histories accompanied the development of the CEMP: an administrative history, an environmental history, and a history of changing public perception of not only nuclear testing, but other activities involving radiation such as waste transportation, as well. Although vital, those histories will be provided only as background to the subject of this study, the oral histories gathered in this project. The oral histories collected open a window into the nuclear testing history of Nevada and Utah that has not heretofore been opened. The nuclear industry has generated a great deal of positive and negative reaction since its inception. The CEMP emerged with specific objectives. It was designed to provide information to potential downwind communities and counter negative perceptions by creating more community involvement and education about the testing. The current objectives of the …
Date: July 1, 2004
Creator: DeSilva, Susan
System: The UNT Digital Library
Role of C and P Sites on the Chemical Activity of Metal Carbide and Phosphides: From Clusters to Single-Crystal Surfaces (open access)

Role of C and P Sites on the Chemical Activity of Metal Carbide and Phosphides: From Clusters to Single-Crystal Surfaces

Transition metal carbides and phosphides have shown tremendous potential as highly active catalysts. At a microscopic level, it is not well understood how these new catalysts work. Their high activity is usually attributed to ligand or/and ensemble effects. Here, we review recent studies that examine the chemical activity of metal carbide and phosphides as a function of size, from clusters to extended surfaces, and metal/carbon or metal/phosphorous ratio. These studies reveal that the C and P sites in these compounds cannot be considered as simple spectators. They moderate the reactivity of the metal centers and provide bonding sites for adsorbates.
Date: July 1, 2007
Creator: Rodriguez, J. A.; Vines, F.; Liu, P. & Illas, F.
System: The UNT Digital Library
Volume visualization of multiple alignment of large genomicDNA (open access)

Volume visualization of multiple alignment of large genomicDNA

Genomes of hundreds of species have been sequenced to date, and many more are being sequenced. As more and more sequence data sets become available, and as the challenge of comparing these massive ''billion basepair DNA sequences'' becomes substantial, so does the need for more powerful tools supporting the exploration of these data sets. Similarity score data used to compare aligned DNA sequences is inherently one-dimensional. One-dimensional (1D) representations of these data sets do not effectively utilize screen real estate. As a result, tools using 1D representations are incapable of providing informatory overview for extremely large data sets. We present a technique to arrange 1D data in 3D space to allow us to apply state-of-the-art interactive volume visualization techniques for data exploration. We demonstrate our technique using multi-millions-basepair-long aligned DNA sequence data and compare it with traditional 1D line plots. The results show that our technique is superior in providing an overview of entire data sets. Our technique, coupled with 1D line plots, results in effective multi-resolution visualization of very large aligned sequence data sets.
Date: July 25, 2005
Creator: Shah, Nameeta; Dillard, Scott E.; Weber, Gunther H. & Hamann, Bernd
System: The UNT Digital Library
Application of Electron Backscatter Diffraction to Phase Identification (open access)

Application of Electron Backscatter Diffraction to Phase Identification

The identification of crystalline phases in solids requires knowledge of two microstructural properties: crystallographic structure and chemical composition. Traditionally, this has been accomplished using X-ray diffraction techniques where the measured crystallographic information, in combination with separate chemical composition measurements for specimens of unknown pedigrees, is used to deduce the unknown phases. With the latest microstructural analysis tools for scanning electron microscopes, both the crystallography and composition can be determined in a single analysis utilizing electron backscatter diffraction and energy dispersive spectroscopy, respectively. In this chapter, we discuss the approach required to perform these experiments, elucidate the benefits and limitations of this technique, and detail via case studies how composition, crystallography, and diffraction contrast can be used as phase discriminators.
Date: July 16, 2008
Creator: El-Dasher, B S & Deal, A
System: The UNT Digital Library
Electron Backscatter Diffraction in Low Vacuum Conditions (open access)

Electron Backscatter Diffraction in Low Vacuum Conditions

Most current scanning electron microscopes (SEMs) have the ability to analyze samples in a low vacuum mode, whereby a partial pressure of water vapor is introduced into the SEM chamber, allowing the characterization of nonconductive samples without any special preparation. Although the presence of water vapor in the chamber degrades electron backscatter diffraction (EBSD) patterns, the potential of this setup for EBSD characterization of nonconductive samples is immense. In this chapter we discuss the requirements, advantages and limitations of low vacuum EBSD (LV-EBSD), and present how this technique can be applied to a two-phase ceramic composite as well as hydrated biominerals as specific examples of when LV-EBSD can be invaluable.
Date: July 17, 2008
Creator: El-Dasher, B S & Torres, S G
System: The UNT Digital Library
Measurement of Simulated Waste Glass Viscosity (open access)

Measurement of Simulated Waste Glass Viscosity

A new high-temperature glass viscometer instrument was established and evaluated using a simulated waste glass in a comparative test with eight other laboratories and viscometers. The unit has distinct advantages in physical size, the amount of glass required for testing, and the simplicity of operation. These advantages can be important for work with radioactive materials. Results from the comparison indicate excellent accuracy and repeatability.
Date: July 10, 2002
Creator: Schumacher, R. F.
System: The UNT Digital Library
A Web Services Data Analysis Grid (open access)

A Web Services Data Analysis Grid

The trend in large-scale scientific data analysis is to exploit compute, storage and other resources located at multiple sites, and to make those resources accessible to the scientist as if they were a single, coherent system. Web technologies driven by the huge and rapidly growing electronic commerce industry provide valuable components to speed the deployment of such sophisticated systems. Jefferson Lab, where several hundred terabytes of experimental data are acquired each year, is in the process of developing a web-based distributed system for data analysis and management. The essential aspects of this system are a distributed data grid (site independent access to experiment, simulation and model data) and a distributed batch system, augmented with various supervisory and management capabilities, and integrated using Java and XML-based web services.
Date: July 2002
Creator: Watson, William A., III; Bird, Ian; Chen, Jie; Hess, Bryan; Kowalski, Andy & Chen, Ying
System: The UNT Digital Library
Steam Digest: Volume IV (open access)

Steam Digest: Volume IV

This edition of the Steam Digest is a compendium of 2003 articles on the technical and financial benefits of steam efficiency, presented by the stakeholders of the U.S. Department of Energy's BestPractices Steam effort.
Date: July 1, 2004
Creator: unknown
System: The UNT Digital Library
RECENT ADVANCES IN THE DEVELOPMENT OF THE HYBRID SULFUR PROCESS FOR HYDROGEN PRODUCTION (open access)

RECENT ADVANCES IN THE DEVELOPMENT OF THE HYBRID SULFUR PROCESS FOR HYDROGEN PRODUCTION

Thermochemical processes are being developed to provide global-scale quantities of hydrogen. A variant on sulfur-based thermochemical cycles is the Hybrid Sulfur (HyS) Process, which uses a sulfur dioxide depolarized electrolyzer (SDE) to produce the hydrogen. In the HyS Process, sulfur dioxide is oxidized in the presence of water at the electrolyzer anode to produce sulfuric acid and protons. The protons are transported through a cation-exchange membrane electrolyte to the cathode and are reduced to form hydrogen. In the second stage of the process, the sulfuric acid by-product from the electrolyzer is thermally decomposed at high temperature to produce sulfur dioxide and oxygen. The two gases are separated and the sulfur dioxide recycled to the electrolyzer for oxidation. The Savannah River National Laboratory (SRNL) has been exploring a fuel-cell design concept for the SDE using an anolyte feed comprised of concentrated sulfuric acid saturated with sulfur dioxide. The advantages of this design concept include high electrochemical efficiency and small footprint compared to a parallel-plate electrolyzer design. This paper will provide a summary of recent advances in the development of the SDE for the HyS process.
Date: July 22, 2010
Creator: Hobbs, D.
System: The UNT Digital Library
Biofuel Economics (open access)

Biofuel Economics

As concerns regarding increasing energy prices, global warming and renewable resources continue to grow, so has scientific discovery into agricultural biomass conversion. Plant Biomass Conversion addresses both the development of plant biomass and conversion technology, in addition to issues surrounding biomass conversion, such as the affect on water resources and soil sustainability. This book also offers a brief overview of the current status of the industry and examples of production plants being used in current biomass conversion efforts.
Date: July 15, 2011
Creator: Klein-Marcuschamer, Daniel; Holmes, Brad; Simmons, Blake & Blanch, Harvey
System: The UNT Digital Library
Magnetic Neutron Scattering (open access)

Magnetic Neutron Scattering

Much of our understanding of the atomic-scale magnetic structure and the dynamical properties of solids and liquids was gained from neutron-scattering studies. Elastic and inelastic neutron spectroscopy provided physicists with an unprecedented, detailed access to spin structures, magnetic-excitation spectra, soft-modes and critical dynamics at magnetic-phase transitions, which is unrivaled by other experimental techniques. Because the neutron has no electric charge, it is an ideal weakly interacting and highly penetrating probe of matter's inner structure and dynamics. Unlike techniques using photon electric fields or charged particles (e.g., electrons, muons) that significantly modify the local electronic environment, neutron spectroscopy allows determination of a material's intrinsic, unperturbed physical properties. The method is not sensitive to extraneous charges, electric fields, and the imperfection of surface layers. Because the neutron is a highly penetrating and non-destructive probe, neutron spectroscopy can probe the microscopic properties of bulk materials (not just their surface layers) and study samples embedded in complex environments, such as cryostats, magnets, and pressure cells, which are essential for understanding the physical origins of magnetic phenomena. Neutron scattering is arguably the most powerful and versatile experimental tool for studying the microscopic properties of the magnetic materials. The magnitude of the cross-section of the neutron …
Date: July 30, 2004
Creator: Zaliznyak ,I. A. & Lee, S. H.
System: The UNT Digital Library