3-D electromagnetic modeling of wakefields in accelerator components (open access)

3-D electromagnetic modeling of wakefields in accelerator components

We discuss the use of 3-D finite-difference time-domain (FDTD) electromagnetic codes for modeling accelerator components. Computational modeling of cylindrically symmetric structures such as induction accelerator cells has been very successful in predicting the wake potential and wake impedances of these structures, but full 3-D modeling of complex structures has been limited due to substantial computer resources required for a full 3-D model. New massively parallel 3-D time domain electromagnetic codes now under development using conforming unstructured meshes allow a substantial increase in the geometric fidelity of the structures being modeled. Development of these new codes are discussed in context of applicability to accelerator problems. Various 3-D structures are tested with an existing cubical cell FDTD code and wake impedances compared with simple analytic models for the structures; results will be used as benchmarks for testing the new time time domain codes. Structures under consideration include a stripline beam position monitor as well as circular and elliptical apertures in circular waveguides. Excellent agreement for monopole and dipole impedances with models were found for these structures below the cutoff frequency of the beam line.
Date: September 18, 1996
Creator: Poole, B.R.; Caporaso, G.J.; Ng, Wang C.; Shang, C.C. & Steich, D.
System: The UNT Digital Library
A 4.2 GS/S Synchronized Vertical Excitation System for SPS Studies - Steps Toward Wideband Feedback (open access)

A 4.2 GS/S Synchronized Vertical Excitation System for SPS Studies - Steps Toward Wideband Feedback

None
Date: October 18, 2013
Creator: Fox, J. D.; Olsen, J.; Rivetta, C.; Rivetta, I.; Turgut, O.; Uemura, S. et al.
System: The UNT Digital Library
25 megajoule energy storage and delivery system for the Shiva laser (open access)

25 megajoule energy storage and delivery system for the Shiva laser

A 25 megajoule, 20 kV capacitive energy storage and delivery system has been built and tested for Shiva--a 20 arm, 10 kJ, 20 TW neodymium glass fusion research laser. This system supplies over 3.5 megamperes to xenon flashlamps for optical pumping of the laser amplifier. About 15% of the energy is used to establish magnetic fields within Faraday rotator glass. A digital based control and diagnostics scheme is employed through the entire pulse power system. This scheme utilizes a distributed digital data bus that addresses every element through two levels of optical isolation. The interfacing of low level digital circuitry to a pulse power environment is discussed, as well as the design and performance of the total system. Cost and manufacturing details are important in a project of this size. The projected cost goal of 27 cents/joule, installed and operating, has been met. The general approach to the design, transient analysis, manufacture, and activation of this large power conditioning system is also discussed.
Date: October 18, 1977
Creator: Gagnon, W.L.; Rupert, P. R.; Berkbigler, L.; Carder, B. M.; Gritton, D. G.; Holloway, R. W. et al.
System: The UNT Digital Library
100-Picometer Interferometry for EUVL (open access)

100-Picometer Interferometry for EUVL

Future extreme ultraviolet lithography (EWL) steppers will, in all likelihood, have six-mirror projection cameras. To operate at the diffraction limit over an acceptable depth of focus each aspheric mirror will have to be fabricated with an absolute figure accuracy approaching 100 pm rms. We are currently developing visible light interferometry to meet this need based on modifications of our present phase shifting diffraction interferometry (PSDI) methodology where we achieved an absolute accuracy of 250pm. The basic PSDI approach has been further simplified, using lensless imaging based on computational diffractive back-propagation, to eliminate auxiliary optics that typically limit measurement accuracy. Small remaining error sources, related to geometric positioning, CCD camera pixel spacing and laser wavelength, have been modeled and measured. Using these results we have estimated the total system error for measuring off-axis aspheric EUVL mirrors with this new approach to interferometry.
Date: March 18, 2002
Creator: Sommargren, G. E.; Phillion, D. W.; Johnson, M. A.; Nguyen, N. O.; Barty, A.; Snell, F. J. et al.
System: The UNT Digital Library
11th International Conference of Radiation Research (open access)

11th International Conference of Radiation Research

Topics discussed in the conference included the following: Radiation Physics, Radiation Chemistry and modelling--Radiation physics and dosimetry; Electron transfer in biological media; Radiation chemistry; Biophysical and biochemical modelling; Mechanisms of DNA damage; Assays of DNA damage; Energy deposition in micro volumes; Photo-effects; Special techniques and technologies; Oxidative damage. Molecular and cellular effects-- Photobiology; Cell cycle effects; DNA damage: Strand breaks; DNA damage: Bases; DNA damage Non-targeted; DNA damage: other; Chromosome aberrations: clonal; Chromosomal aberrations: non-clonal; Interactions: Heat/Radiation/Drugs; Biochemical effects; Protein expression; Gene induction; Co-operative effects; ``Bystander'' effects; Oxidative stress effects; Recovery from radiation damage. DNA damage and repair -- DNA repair genes; DNA repair deficient diseases; DNA repair enzymology; Epigenetic effects on repair; and Ataxia and ATM.
Date: July 18, 1999
Creator: unknown
System: The UNT Digital Library
2002 Gordon Research Conference on Molecular Evolution (open access)

2002 Gordon Research Conference on Molecular Evolution

Emphasis was placed on current unpublished research and discussion of the future target areas in this field.
Date: January 18, 2002
Creator: unknown
System: The UNT Digital Library
2002 Review of Neutron and Non Neutron Nuclear Data (open access)

2002 Review of Neutron and Non Neutron Nuclear Data

Review articles are in preparation for the 2003 edition of the CRC's Handbook of Chemistry and Physics dealing with both non-neutron and neutron nuclear data. Highlights include: withdrawal of the claim for discovery of element 118; new measurements of isotopic abundances have led to changes for many elements; a new set of recommended standards for calibration of {gamma}-ray energies have been published for many nuclides; new half-life measurements reported for very short lived isotopes, many long-lived nuclides and {beta}{beta} decay measurements for quasi-stable nuclides; a new reassessment of spontaneous fission (sf) half-lives for ground state nuclides, distinguishing half-lives from sf decay and cluster decay half-lives and the new cluster-fission decay; charged particle cross sections, (n,p) and (n,{alpha}) measurements for thermal neutrons incident on light nuclides; new thermal (n,{gamma}) cross sections and neutron resonance integrals measured. Details are presented.
Date: August 18, 2002
Creator: Holden, N. E.
System: The UNT Digital Library
2007 Archaea: Ecology, Metabolism and Molecular Biology (open access)

2007 Archaea: Ecology, Metabolism and Molecular Biology

The Archaea are a fascinating and diverse group of prokaryotic organisms with deep roots overlapping those of eukaryotes. The focus of this GRC conference, 'Archaea: Ecology Metabolism & Molecular Biology', expands on a number of emerging topics highlighting the evolution and composition of microbial communities and novel archaeal species, their impact on the environment, archaeal metabolism, and research that stems from sequence analysis of archaeal genomes. The strength of this conference lies in its ability to couple reputable areas with new scientific topics in an atmosphere of stimulating exchange. This conference remains an excellent opportunity for younger scientists to interact with world experts in this field.
Date: September 18, 2008
Creator: Gray, Imke Schroeder Nancy Ryan
System: The UNT Digital Library
2009 Exploring Giant Planets on NIF: A New Generation of Condensed Matter Workshop (open access)

2009 Exploring Giant Planets on NIF: A New Generation of Condensed Matter Workshop

None
Date: December 18, 2009
Creator: Eggert, J. H.; Robey, H. F.; Spears, B. K.; Thomas, C. A.; Weber, S. V.; Wilson, D. C. et al.
System: The UNT Digital Library
2010 CELL AND MOLECULAR FUNGAL BIOLOGY GORDON RESEARCH CONFERENCE, JUNE 13-18, 2010 (open access)

2010 CELL AND MOLECULAR FUNGAL BIOLOGY GORDON RESEARCH CONFERENCE, JUNE 13-18, 2010

The Cellular and Molecular Fungal Biology Conference provides a forum for presentation of the latest advances in fungal research with an emphasis on filamentous fungi. This open-registration scientific meeting brings together the leading scientists from academia, government and industry to discuss current research results and future directions at Holderness School, an outstanding venue for scientific interaction. A key objective of the conference is to foster interaction among scientists working on model fungi such as Saccharomyces cerevisiae, Schizosaccharomyces pombe, Neurospora crassa and Aspergillus nidulans and scientists working on a variety of filamentous fungi whose laboratory tractability is often inversely proportional to their medical, industrial or ecological importance. Sessions will be devoted to Systems Biology, Fungi and Cellulosic Biomass, Small RNAs, Population Genomics, Symbioses, Pathogenesis, Membrane Trafficking and Polarity, and Cytoskeleton and Motors. A session will also be devoted to hot topics picked from abstracts. The CMFB conference provides a unique opportunity to examine the breadth of fungal biology in a small meeting format that encourages in-depth discussion among the attendees.
Date: June 18, 2010
Creator: Momany, Michelle
System: The UNT Digital Library
2010 CORRELATED ELECTRON SYSTEMS GORDON RESEARCH CONFERENCE, JUNE 13-18, 2010 For (open access)

2010 CORRELATED ELECTRON SYSTEMS GORDON RESEARCH CONFERENCE, JUNE 13-18, 2010 For

The 2010 Gordon Conference on Correlated Electron Systems will present cutting-edge research on emergent properties arising from strong electronic correlations. The Conference will feature a wide range of topics, such as the role of topology in condensed matter systems, quantum Hall interferometry and non-Abelian statistics, quantum criticality, metal-insulator transition, quantum effects in conductivity, Dirac quasiparticles, and superconductivity in cuprates and pnictides. In addition, we are reserving two sessions for new developments in this field that may arise in the coming year. The Conference will bring together a collection of investigators who are at the forefront of their field, and will provide opportunities for junior scientists and graduate students to present their work in poster format and exchange ideas with leaders in the field. We intend to have talks by established leaders in the field and also by young researchers who have made seminal contributions to various aspects of correlated electron physics, The collegial atmosphere of this Conference, with programmed discussion sessions as well as opportunities for informal gatherings in the afternoons and evenings, provides an avenue for scientists from different disciplines to brainstorm and promotes cross-disciplinary collaborations in the various research areas represented.
Date: June 18, 2010
Creator: Basov, Dmitri
System: The UNT Digital Library
2010 Electron Donor-Acceptor Interactions Gordon Research Conference, August 8 - 13, 2010. (open access)

2010 Electron Donor-Acceptor Interactions Gordon Research Conference, August 8 - 13, 2010.

The Gordon Research Conference on Electron Donor Acceptor Interactions (GRC EDAI) presents and advances the current frontiers in experimental and theoretical studies of Electron Transfer Processes and Energy Conversion. The fundamental concepts underpinning the field of electron transfer and charge transport phenomena are understood, but fascinating experimental discoveries and novel applications based on charge transfer processes are expanding the discipline. Simultaneously, global challenges for development of viable and economical alternative energy resources, on which many researchers in the field focus their efforts, are now the subject of daily news headlines. Enduring themes of this conference relate to photosynthesis, both natural and artificial, and solar energy conversion. More recent developments include molecular electronics, optical switches, and nanoscale charge transport structures of both natural (biological) and man-made origin. The GRC EDAI is one of the major international meetings advancing this field, and is one of the few scientific meetings where fundamental research in solar energy conversion has a leading voice. The program includes sessions on coupled electron transfers, molecular solar energy conversion, biological and biomimetic systems, spin effects, ultrafast reactions and technical frontiers as well as electron transport in single molecules and devices. In addition to disseminating the latest advances in the …
Date: August 18, 2010
Creator: Meyer, Gerald
System: The UNT Digital Library
2012 Community Earth System Model (CESM) Tutorial - Proposal to DOE (open access)

2012 Community Earth System Model (CESM) Tutorial - Proposal to DOE

The Community Earth System Model (CESM) is a fully-coupled, global climate model that provides state-of-the-art computer simulations of the Earth's past, present, and future climate states. This document provides the agenda and list of participants for the conference. Web materials for all lectures and practical sessions available from: http://www.cesm.ucar.edu/events/tutorials/073012/ .
Date: March 18, 2013
Creator: Holland, Marika & Bailey, David A.
System: The UNT Digital Library
2013 MOLECULAR ENERGY TRANSFER GORDON RESEARCH CONFERENCE (JANUARY 13-18, 2013 - VENTURA BEACH MARRIOTT, VENTURA CA (open access)

2013 MOLECULAR ENERGY TRANSFER GORDON RESEARCH CONFERENCE (JANUARY 13-18, 2013 - VENTURA BEACH MARRIOTT, VENTURA CA

Sessions covered all areas of molecular energy transfer, with 10 sessions of talks and poster sessions covering the areas of :  Energy Transfer in Inelastic and Reactive Scattering  Energy Transfer in Photoinitiated and Unimolecular Reactions  Non-adiabatic Effects in Energy Transfer  Energy Transfer at Surfaces and Interfaces  Energy Transfer in Clusters, Droplets, and Aerosols  Energy Transfer in Solution and Solid  Energy Transfer in Complex Systems  Energy Transfer: New vistas and horizons  Molecular Energy Transfer: Where Have We Been and Where are We Going?
Date: October 18, 2012
Creator: Reid, Scott A.
System: The UNT Digital Library
232U CONTENT OF SAPPHIRE MATERIAL. (open access)

232U CONTENT OF SAPPHIRE MATERIAL.

None
Date: July 18, 2000
Creator: KANE,W.R.; LEMLEY,J.R.; VANIER,P.E. & FORMAN,L.
System: The UNT Digital Library
2l-nl{prime} x-ray transitions from neonlike charge states of the row 5 metals with 39 {le} Z {le} 46 (open access)

2l-nl{prime} x-ray transitions from neonlike charge states of the row 5 metals with 39 {le} Z {le} 46

X-ray spectra of 2l-2l{prime} transitions with 3 {le} n {le} 12 in the row five transition metals zirconium (Z = 40), niobium (Z = 41), molybdenum (Z = 42) and palladium (Z = 46) from charge states around neonlike have been observed from Alcator C-Mod plasmas. Accurate wavelengths ({+-} .2 m{angstrom}) have been determined by comparison with neighboring argon, chlorine and sulfur lines with well known wavelengths. Line identifications have been made by comparison to ab initio atomic structure calculations, using a fully relativistic, parametric potential code. For neonlike ions, calculated wavelengths and oscillator strengths are tabulated for 2p-nd transitions in Y (Z = 39), Tc (Z = 43), Ru (Z = 44) and Rh (Z = 45) with n = 6 and 7. The magnitude of the configuration interaction between the (2p{sup 5}){sub 1/2}6d{sub 3/2} J = 1 level and the (2p{sup 5}){sub 3/2}7D{sub 5/2} J = 1 levels is demonstrated as a function of atomic number for successive neonlike ions. Measured spectra of selected transitions in the aluminum-, magnesium-, sodium- and fluorine like isosequences are also shown.
Date: March 18, 1996
Creator: Rice, J. E.; Terry, J. L.; Marmar, E. S.; Fournier, K. B.; Goldstein, W. H.; Finkenthal, M. et al.
System: The UNT Digital Library
2nd Feasibility Study of a Muon Storage Ring Neutrino Factory (open access)

2nd Feasibility Study of a Muon Storage Ring Neutrino Factory

The design and simulated performance of a second feasibility study are presented. The efficiency of producing muons is {approx} 0.17 {micro}/p with 24 GeV protons. This study was sponsored by the BNL Director, with BNL site specific driver and layout. It was a follow on to the First Study[2] sponsored by the Fermilab Director, with Fermilab site specific driver and layout, and was the main US collaboration conceptual effort during the past year. Other studies, and technical work by the collaboration is reported in other papers.
Date: June 18, 2001
Creator: Ozaki, S.; Palmer, R. B. & Zisman, M. S.
System: The UNT Digital Library
2XIIB computer data acquisition system (open access)

2XIIB computer data acquisition system

All major plasma diagnostic measurements from the 2XIIB experiment are recorded, digitized, and stored by the computer data acquisition system. The raw data is then examined, correlated, reduced, and useful portions are quickly retrieved which direct the future conduct of the plasma experiment. This is done in real time and on line while the data is current. The immediate availability of this pertinent data has accelerated the rate at which the 2XII personnel have been able to gain knowledge in the study of plasma containment and fusion interaction. The up time of the experiment is being used much more effectively than ever before. This paper describes the hardware configuration of our data system in relation to various plasma parameters measured, the advantages of powerful software routines to reduce and correlate the data, the present plans for expansion of the system, and the problems we have had to overcome in certain areas to meet our original goals. (auth)
Date: November 18, 1975
Creator: Tyler, G.C.
System: The UNT Digital Library
2XIIB getter material problems (open access)

2XIIB getter material problems

The uniformity of wire characteristics is vital to the reliable long- time operation of the titanium alloy wire. Of particular importance is the diameter, total emissivity, and alloy mix. The getter wire must be operated at a minimum rate while the life is determined by the maximum rate. At a particular current the difference between the maximum and minimum rate is determined by variations in wire characteristics. Small percentage variations in these characteristics can result in large variations in gettering rate. (auth)
Date: November 18, 1975
Creator: Vogtlin, G. E.
System: The UNT Digital Library
3D Surface Mapping of Capsule Fill-Tube Assemblies used in Laser-Driven Fusion Targets (open access)

3D Surface Mapping of Capsule Fill-Tube Assemblies used in Laser-Driven Fusion Targets

This paper presents the development of a 3D surface mapping system used to measure the surface of a fusion target Capsule Fill-Tube Assembly (CFTA). The CFTA consists of a hollow Ge-doped plastic sphere, called a capsule, ranging in outer diameter between 2.2 mm and 2.6 mm and an attached 150 {micro}m diameter glass-core fill-tube that tapers down to a 10{micro} diameter at the capsule. The mapping system is an enabling technology to facilitate a quality assurance program and to archive 3D surface information of each capsule used in fusion ignition experiments that are currently being performed at the National Ignition Facility (NIF). The 3D Surface Mapping System is designed to locate and quantify surface features with a height of 50 nm and 300 nm in width or larger. Additionally, the system will be calibrated such that the 3D measured surface can be related to the capsule surface angular coordinate system to within 0.25 degree (1{sigma}), which corresponds to approximately 5 {micro}m linear error on the capsule surface.
Date: February 18, 2011
Creator: Buice, E. S.; Alger, E. T.; Antipa, N. A.; Bhandarkar, S. D.; Biesiada, T. A.; Conder, A. D. et al.
System: The UNT Digital Library
The (3He,tf) as a surrogate reaction to determine (n,f) cross sections in the 10 to 20 MeV energy range (open access)

The (3He,tf) as a surrogate reaction to determine (n,f) cross sections in the 10 to 20 MeV energy range

None
Date: February 18, 2009
Creator: Basunia, M. S.; Clark, R. M.; Goldblum, B. L.; Bernstein, L. A.; Phair, L.; Burke, J. T. et al.
System: The UNT Digital Library
AB INITIO molecular orbital studies of some high temperature metal halide complexes. [300/sup 0/--500/sup 0/C] (open access)

AB INITIO molecular orbital studies of some high temperature metal halide complexes. [300/sup 0/--500/sup 0/C]

The use of ab initio molecular orbital calculations to aid in the characterization, i.e., structures and energies, of metal halide complexes present in high temperature salt vapors has been investigated. Standard LCAO-SCF methods were used and calculations were carried out using the minimal STO-3G basis set. The complexes included in this study were Al/sub 2/F/sub 6/, Al/sub 2/Cl/sub 6/, AlF/sub 3/ NH/sub 3/, AlCl/sub 3/ NH/sub 3/, and AlF/sub 3/ N/sub 2/. The Al/sub 2/X/sub 6/ complexes are found to have D/sub 2h/ symmetry in agreement with most experimental results. A planar form was found to be considerably higher in energy. The AlX/sub 3/ NH/sub 3/ complexes are found to have C/sub 3v/ symmetry with a small barrier to rotation about the Al-N axis. The AlF/sub 3/ N/sub 2/ complex is found to be weakly bound together with a binding energy of -8.2 kcal/mole at the STO-3G level.
Date: September 18, 1978
Creator: Curtiss, L.A.
System: The UNT Digital Library
The Ability of MM5 to Simulate Ice Clouds: Systematic Comparison between Simulated and Measured Fluxes and Lidar/Radar Profiles at SIRTA Atmospheric Observatory (open access)

The Ability of MM5 to Simulate Ice Clouds: Systematic Comparison between Simulated and Measured Fluxes and Lidar/Radar Profiles at SIRTA Atmospheric Observatory

Ice clouds play a major role in the radiative energy budget of the Earth-atmosphere system (Liou 1986). Their radiative effect is governed primarily by the equilibrium between their albedo and greenhouse effects. Both macrophysical and microphysical properties of ice clouds regulate this equilibrium. For quantifying the effect of these clouds onto climate and weather systems, they must be properly characterized in atmospheric models. In this paper we use remote-sensing measurements from the SIRTA ground based atmospheric observatory (Site Instrumental de Recherche par Teledetection Atmospherique, http://sirta.lmd.polytechnique.fr). Lidar and radar observations taken over 18 months are used, in order to gain statistical confidence in the model evaluation. Along this period of time, 62 days are selected for study because they contain parts of ice clouds. We use the ''model to observations'' approach by simulating lidar and radar signals from MM5 outputs. Other more classical variables such as shortwave and longwave radiative fluxes are also used. Four microphysical schemes, among which that proposed by Reisner et al. (1998) with original or modified parameterizations of particle terminal fall velocities (Zurovac-Jevtic and Zhang 2003, Heymsfield and Donner 1990), and the simplified Dudhia (1989) scheme are evaluated in this study.
Date: March 18, 2005
Creator: Chiriaco, M.; Vautard, R.; Chepfer, H.; Haeffelin, M.; Wanherdrick, Y.; Morille, Y. et al.
System: The UNT Digital Library
Absolute Measurement of Electron Cloud Density in a Positively-Charged Particle Beam (open access)

Absolute Measurement of Electron Cloud Density in a Positively-Charged Particle Beam

Clouds of stray electrons are ubiquitous in particle accelerators and frequently limit the performance of storage rings. Earlier measurements of electron energy distribution and flux to the walls provided only a relative electron cloud density. We have measured electron accumulation using ions expelled by the beam. The ion energy distribution maps the depressed beam potential and gives the dynamic cloud density. Clearing electrode current reveals the static background cloud density, allowing the first absolute measurement of the time-dependent electron cloud density during the beam pulse.
Date: May 18, 2006
Creator: Covo, M K; Molvik, A W; Friedman, A; Vay, J; Seidl, P A; Logan, B G et al.
System: The UNT Digital Library