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X-Band Photonic Band-Gap Accelerator Structure Breakdown Experiment
In order to understand the performance of photonic band-gap (PBG) structures under realistic high gradient, high power, high repetition rate operation, a PBG accelerator structure was designed and tested at X band (11.424 GHz). The structure consisted of a single test cell with matching cells before and after the structure. The design followed principles previously established in testing a series of conventional pillbox structures. The PBG structure was tested at an accelerating gradient of 65 MV/m yielding a breakdown rate of two breakdowns per hour at 60 Hz. An accelerating gradient above 110 MV/m was demonstrated at a higher breakdown rate. Significant pulsed heating occurred on the surface of the inner rods of the PBG structure, with a temperature rise of 85 K estimated when operating in 100 ns pulses at a gradient of 100 MV/m and a surface magnetic field of 890 kA/m. A temperature rise of up to 250 K was estimated for some shots. The iris surfaces, the location of peak electric field, surprisingly had no damage, but the inner rods, the location of the peak magnetic fields and a large temperature rise, had significant damage. Breakdown in accelerator structures is generally understood in terms of electric …
Date:
June 11, 2012
Creator:
Marsh, Roark A.; Shapiro, Michael A.; Temkin, Richard J.; Dolgashev, Valery A.; Laurent, Lisa L.; Lewandowski, James R. et al.
Object Type:
Article
System:
The UNT Digital Library
X-ray absorption and magnetic circular dichroism studies of Co2FeAl in magnetic tunnel junctions
The bulk magnetic moment and the element specific magnetic moment of Co{sub 2}FeAl thin films were examined as a function of annealing temperature by alternating gradient magnetometer (AGM) and X-ray absorption spectroscopy (XAS)/X-ray magnetic circular dichroism (XMCD), respectively. A high magnetic moment can be achieved for all annealing temperatures and the predicted bulk and interface magnetic moment of about 5 {tilde A}{sub B} are reached via heating. We will also present tunnel magnetoresistance (TMR) values of up to 153% at room temperature and 260% at 13 K for MgO based magnetic tunnel junctions (MTJs) with Co{sub 2}FeAl and Co-Fe electrodes.
Date:
January 11, 2010
Creator:
Ebke, D.; Kugler, Z.; Thomas, P.; Schebaum, O.; Schafers, M.; Nissen, D. et al.
Object Type:
Article
System:
The UNT Digital Library
X-ray Absorption Spectroscopy Characterization of Zn Underpotential Deposition on Au(111) from Phosphate Supporting Electrolyte
Zn K-edge X-ray absorption spectroscopy (XAS) has been used to investigate the structure of Zn monolayers prepared on Au(111) electrodes via underpotential deposition (UPD) from phosphate supporting electrolyte. Theoretical modeling of the XAS data indicates that the Zn adatoms adopt a commensurate ({radical}3x{radical}3)R30{sup o} ({mu}{sub sc} = 0.33) adlayer structure and reside within the 3-fold hollow sites of the Au(111) surface. Meanwhile, phosphate counter-ions co-adsorb on the UPD adlayer and bridge between the Zn adatoms in a ({radical}3x{radical}3)R30{sup o} ({mu}{sub sc} = 0.33) configuration, with each phosphorous atom residing above a vacant 3-fold hollow site of the Au(111). Significantly, this surface structure is invariant between the electrochemical potential for UPD adlayer formation and the onset of bulk Zn electrodeposition. Analysis of the Zn K-edge absorption onset also presents the possibility that the Zn adatoms do not fully discharge during the process of UPD, which had been proposed in prior voltammetric studies of the phosphate/Zn(UPD)/Au(111) system.
Date:
December 11, 2009
Creator:
Lee, J. R.; O'Malley, R. L.; O'Connell, T. J.; Vollmer, A. & Rayment, T.
Object Type:
Article
System:
The UNT Digital Library
X-ray diffraction measurement of residual stresses in delta plutonium
Residual stresses in delta plutonium can be measured by the x-ray diffractometer method. This was accomplished with the aid of an experimental tantalum x-ray target. Preliminary experiments are encouraging and indicate that stresses may be determined precisely and rapidly. Future work will involve determination of x-ray elastic constants, instrument calibration with stress-free standards, higher x-ray power and more sophisticated monochromatization methods. 4 refs., 4 figs., 1 tab.
Date:
September 11, 1990
Creator:
Steinmeyer, P.A.
Object Type:
Report
System:
The UNT Digital Library
X-Ray Holography at Lawrence Livermore National Laboratory
The x-ray holography program at the Lawrence Livermore National Laboratory has two principal goals: (1) the development of x-ray diffraction techniques for DNA sequence analysis and (2) the development of x-ray laser holography for structural analysis of intact biological cells and organelles. DNA sequence analysis will be accomplished by applying x-ray diffraction techniques to determine the ensemble average of the sequence of labels along the individual elements of crystalline DNA. X-ray laser holographic imaging will be accomplished by applying three dimensional x-ray holography to elucidate the structure of few hundred angstrom objects such as 300 {Angstrom} chromatin fibers, nuclear pores and nucleic acid replication complexes in living cells. Existing laboratory x-ray lasers will be utilized to produce flash x-ray holograms of the biological structures.
Date:
October 11, 1990
Creator:
Trebes, J.; Annese, C.; Birdsall, D.; Brase, J.; Gray, J.; Lane, S. et al.
Object Type:
Article
System:
The UNT Digital Library
X-Ray imager power source on distribution trailers
This Acceptance for Beneficial Use documents the work completed on the addition of an X-ray cable reel on distribution trailer HO-64-3533 for core sampling equipment. Work and documentation remaining to be completed is identified.
Date:
September 11, 1996
Creator:
Johns, B.R.
Object Type:
Report
System:
The UNT Digital Library
X-ray imaging of vortex cores in confined magnetic structures
Cores of magnetic vortices in micron-sized NiFe disk structures, with thicknesses between 150 and 50 nm, were imaged and analysed by high resolution magnetic soft X-ray microscopy. A decrease of the vortex core radius was observed, from #24; ~38 to 18 nm with decreasing disk thickness. By comparing with full 3D micromagnetic simulations showing the well-known barrel structure, we obtained excellent agreement taking into account instrumental broadening and a small perpendicular anisotropy. The proven magnetic spatial resolution of better than 25 nm was sufficient to identify a negative dip close to the vortex core, originating from stray fields of the core. Magnetic vortex structures can serve as test objects for evaluating sensitivity and spatial resolution of advanced magnetic microscopy techniques.
Date:
February 11, 2011
Creator:
Fischer, P.; Im, M.-Y.; Kasai, S.; Yamada, K.; Ono, T. & Thiaville, A.
Object Type:
Article
System:
The UNT Digital Library
X-ray Scattering Techniques for Characterization of Nanosystems in Lifescience
The intent of this chapter is to provide the basics of using x-ray diffraction techniques in order to obtain information on the structure and morphology of the nanosystems, and also to point out some of its strengths and weaknesses when compare to other characterization techniques. X-ray scattering examines over a wide range of density domains from a tenth to a thousandth angstrom. Essentially, this covers a whole range of condensed matter, including the structure and morphology of nanosystems, particularly useful for examining nanostructures in lifescience. This range of domain size requires both the wide-angle x-ray scattering (WAXS) and small-angle (SAXS) x-ray scattering techniques. Roughly WAXS covers from 2 nm down, and SAXS covers from .5 nm to 100 nm and possibly 1,000 nm for a finely tuned instrument. Brief theoretical description of both WAXS and SAXS will be given in this chapter. WAXS, by itself is a powerful technique in providing information on the crystallographic structure or lack of structure, atomic positions and sizes in a unit cell, to some extend, chemical compositions and as well as chemical stoichiometry. Examples of such experiments will also be given. In order to be able to describe the technique of x-ray scattering, some …
Date:
April 11, 2005
Creator:
Saw, C K
Object Type:
Article
System:
The UNT Digital Library
XAL Adoption Experience at LCLS
XAL is a high level accelerator application framework originally developed by the Spallation Neutron Source (SNS), Oak Ridge National Laboratory. The XAL framework provides generic hierarchical view for an accelerator as well as many utility tools. In XAL, a built-in physics model calculates either single particle or beam envelope tracking for physics parameters. Modifications to the original XAL model are necessary for the Linac Coherent Light Source (LCLS). Work was done to manipulate MAD deck output within a database in support of the XAL configuration and model. The XAL graphical user interface has been replaced by a SLAC specific design. New applications based on the framework are also discussed in this paper.
Date:
December 11, 2009
Creator:
Chu, P.; Woodley, M.; Chan, A.; Chevtsov, S.; Fairley, D.; Grunhaus, E. et al.
Object Type:
Article
System:
The UNT Digital Library
XAL-Based Applications and Online Models for LCLS
XAL, a high-level accelerator application framework originally developed at the Spallation Neutron Source (SNS), Oak Ridge National Laboratory, has been adopted by the Linac Coherent Light Source (LCLS) project. The work includes proper relational database schema modification to better suit XAL configuration data requirement, addition of new device types for LCLS online modeling purpose, longitudinal coordinate system change to better represent the LCLS electron beam rather than proton or ion beam in the original SNS XAL design, intensively benchmark with MAD and present SLC modeling system for the online model, and various new features to the XAL framework. Storing online model data in a relational database and providing universal access methods for other applications is also described here.
Date:
December 11, 2009
Creator:
Chu, P.; Woodley, M.; Iverson, R.; Krejcik, P.; White, G.; Wu, J. et al.
Object Type:
Article
System:
The UNT Digital Library
XAMath: An XAFS analysis package based on Mathematica{reg_sign}
XAMath is a graphics-based interactive package written with the Mathematica{reg_sign} system for the analysis of XAFS data. Mathematica{reg_sign} offers the advantage of use on several computer platforms, including Unix, IBM Windows, and Macintosh, without any modification of the program. The portability and flexibility of this software has some cost in speed of execution.
Date:
July 11, 1994
Creator:
Wasserman, S. R.
Object Type:
Article
System:
The UNT Digital Library
XE-1 pneumatic actuator failure mode analysis
None
Date:
February 11, 1968
Creator:
Spezialetti, I.R.
Object Type:
Report
System:
The UNT Digital Library
XE-2 nozzle assembly readiness report
None
Date:
July 11, 1968
Creator:
Claassen, L.B.
Object Type:
Report
System:
The UNT Digital Library
Xenon and iodine concentrations in the environs of the T and B Plant
A report of seven stack emissions of I-131 at the T and B plants, detailing the relationship between cooling times and dilution factors for the safe emission of the isotope. From the stack sampling, personal exposure limits for an eight and nine hour day are calculated. The effect of atmospheric conditions appears to be negligible, although periods of atmospheric stagnation may have an effect on the I-131 concentration. Environmental effects are minimized by increasing the cooling times of the isotope charge. Downdrafts near the stack emissions during low dilution increase the radiation level, but do not pose any inhalation hazard.
Date:
December 11, 1945
Creator:
Parker, H. M.
Object Type:
Report
System:
The UNT Digital Library
YALINA-booster Subcritical Assembly Pulsed-Neutron E Xperiments: Detector Dead Time and Apatial Corrections.
In almost every detector counting system, a minimal dead time is required to record two successive events as two separated pulses. Due to the random nature of neutron interactions in the subcritical assembly, there is always some probability that a true neutron event will not be recorded because it occurs too close to the preceding event. These losses may become rather severe for counting systems with high counting rates, and should be corrected before any utilization of the experimental data. This report examines the dead time effects for the pulsed neutron experiments of the YALINA-Booster subcritical assembly. The nonparalyzable model is utilized to correct the experimental data due to dead time. Overall, the reactivity values are increased by 0.19$ and 0.32$ after the spatial corrections for the YALINA-Booster 36% and 21% configurations respectively. The differences of the reactivities obtained with He-3 long or short detectors at the same detector channel diminish after the dead time corrections of the experimental data for the 36% YALINA-Booster configuration. In addition, better agreements between reactivities obtained from different experimental data sets are also observed after the dead time corrections for the 21% YALINA-Booster configuration.
Date:
October 11, 2010
Creator:
Cao, Y.; Gohar, Y. & Division, Nuclear Engineering
Object Type:
Report
System:
The UNT Digital Library
YALINA-booster Subcritical Assembly Pulsed-Neutron Experiments : Data Processing and Spatial Corrections.
The YALINA-Booster experiments and analyses are part of the collaboration between Argonne National Laboratory of USA and the Joint Institute for Power & Nuclear Research - SOSNY of Belarus for studying the physics of accelerator driven systems for nuclear energy applications using low enriched uranium. The YALINA-Booster subcritical assembly is utilized for studying the kinetics of accelerator driven systems with its highly intensive D-T or D-D pulsed neutron source. In particular, the pulsed neutron methods are used to determine the reactivity of the subcritical system. This report examines the pulsed-neutron experiments performed in the YALINA-Booster facility with different configurations for the subcritical assembly. The 1141 configuration with 90% U-235 fuel and the 1185 configuration with 36% or 21% U-235 fuel are examined. The Sjoestrand area-ratio method is utilized to determine the reactivities of the different configurations. The linear regression method is applied to obtain the prompt neutron decay constants from the pulsed-neutron experimental data. The reactivity values obtained from the experimental data are shown to be dependent on the detector locations inside the subcritical assembly and the types of detector used for the measurements. In this report, Bell's spatial correction factors are calculated based on a Monte Carlo model to …
Date:
October 11, 2010
Creator:
Cao, Y.; Gohar, Y. & Division, Nuclear Engineering
Object Type:
Report
System:
The UNT Digital Library
The Year 2000 and the Prospect for an American Women
This report is an overview study on different roles American women played through the history of the country through the year 2000 as homemakers, employees, and society's treatment of them as well.
Date:
August 11, 1977
Creator:
Keesling, Karen
Object Type:
Report
System:
The UNT Digital Library
Year 2000 Computing Crisis: Actions Needed to Ensure Continued Delivery of Veterans Benefits and Health Care Services
Correspondence issued by the General Accounting Office with an abstract that begins "Pursuant to a congressional request, GAO provided information on its recommendations to the Department of Veterans Affairs (VA) for completing key actions necessary to ensure continued delivery of benefits and health care services to veterans beyond January 1, 2000."
Date:
June 11, 1999
Creator:
United States. General Accounting Office.
Object Type:
Text
System:
The UNT Digital Library
Yemen: Background and U.S. Relations
This report provides an overview and analysis of U.S.-Yemeni relations and issues, including evolving political change in Yemeni leadership, ongoing U.S. counterterrorism operations against Al Qaeda in the Arabian Peninsula (AQAP) operatives at large in Yemen's hinterlands, and international efforts to bolster the country's stability despite an array of daunting socio-economic problems.
Date:
February 11, 2015
Creator:
Sharp, Jeremy M.
Object Type:
Report
System:
The UNT Digital Library
Youth and the Labor Force: Background and Trends
None
Date:
July 11, 2013
Creator:
Fernandes-Alcantara, Adrienne L.
Object Type:
Report
System:
The UNT Digital Library
Yucca Mountain Site Charecteization Project Summary of Socioeconomic Data Analysis Conducted in Support of the Radiological Monitoring Program, During FY 2001
This report is a summary of socioeconomic data analyses conducted in support of the Radiological Monitoring Program during fiscal year 2001. Socioeconomic data contained in this report include estimates for the years 2000 and 2001 of the resident population in the vicinity of Yucca Mountain. The estimates presented in this report are based on selected Census 2000 statistics, and housing and population data that were acquired and developed in accordance with LP-RS-00 1 Q-M&0, Scientific Investigation of Economic, Demographic, and Agricultural Characteristics in the Vicinity of Yucca Mountain. The study area from which data were collected is delineated by a radial grid, consisting of 160 grid cells, that is suitable for evaluating the pathways and potential impacts of a release of radioactive materials to the environment within a distance of 84 kilometers from Yucca Mountain. Data are presented in a tabular format by the county, state, area, and grid cell in which housing units, households, and resident population are located. Also included is a visual representation of the distribution of the 2000 residential populations within the study area, showing Census 2000 geography, county boundaries, and taxing district boundaries for selected communities.
Date:
December 11, 2001
Creator:
Roe, L.K.
Object Type:
Report
System:
The UNT Digital Library
Zero-Valent Iron Permeable Reactive Barriers: A Review of Performance
This report briefly reviews issues regarding the implementation of the zero-valent iron permeable reactive barrier (PRB) technology at sites managed by the U.S. Department of Energy (DOE). Initially, the PRB technology, using zero-valent iron for the reactive media, was received with great enthusiasm, and DOE invested millions of dollars testing and implementing PRBs. Recently, a negative perception of the technology has been building. This perception is based on the failure of some deployments to satisfy goals for treatment and operating expenses. The purpose of this report, therefore, is to suggest reasons for the problems that have been encountered and to recommend whether DOE should invest in additional research and deployments. The principal conclusion of this review is that the most significant problems have been the result of insufficient characterization, which resulted in poor engineering implementation. Although there are legitimate concerns regarding the longevity of the reactive media, the ability of zero-valent iron to reduce certain chlorinated hydrocarbons and to immobilize certain metals and radionuclides is well documented. The primary problem encountered at some DOE full-scale deployments has been an inadequate assessment of site hydrology, which resulted in misapplication of the technology. The result is PRBs with higher than expected flow …
Date:
June 11, 2001
Creator:
Korte, NE
Object Type:
Report
System:
The UNT Digital Library
Zeros in $pi$$pi$ scattering
None
Date:
April 11, 1973
Creator:
Pennington, M.R.
Object Type:
Article
System:
The UNT Digital Library
ZGS beam transport for transverse or longitudinally polarized protons
A combination of dipole magnets and a superconducting solenoid is utilized to transform the spin direction of transversely polarized protons from the Argonne ZGS for use in proton-proton scattering experiments.
Date:
August 11, 1977
Creator:
Colton, E.; Auer, I.P. & Beretvas, A.
Object Type:
Report
System:
The UNT Digital Library