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Raising Photoemission Efficiency with Surface Acoustic Waves
We are developing a novel technique that may help increase the efficiency and reduce costs of photoelectron sources used at electron accelerators. The technique is based on the use of Surface Acoustic Waves (SAW) in piezoelectric materials, such as GaAs, that are commonly used as photocathodes. Piezoelectric fields produced by the traveling SAW spatially separate electrons and holes, reducing their probability of recombination, thereby enhancing the photoemission quantum efficiency of the photocathode. Additional advantages could be increased polarization provided by the enhanced mobility of charge carriers that can be controlled by the SAW and the ionization of optically-generated excitons resulting in the creation of additional electron-hole pairs. It is expected that these novel features will reduce the cost of accelerator operation. A theoretical model for photoemission in the presence of SAW has been developed, and experimental tests of the technique are underway.
Date:
July 1, 2012
Creator:
A. Afanasev, F. Hassani, C.E. Korman, V.G. Dudnikov, R.P. Johnson, M. Poelker, K.E.L. Surles-Law
Object Type:
Article
System:
The UNT Digital Library
Intra-beam scattering and its applications to ERL
N/A
Date:
July 1, 2012
Creator:
A., Fedotov
Object Type:
Report
System:
The UNT Digital Library
Potential for Luminosity improvement for low-energy RHIC operations with long bunches
N/A
Date:
July 1, 2012
Creator:
A., Fedotov & Blaskiewicz, M.
Object Type:
Report
System:
The UNT Digital Library
Thermal characteristics of air flow cooling in the lithium ion batteries experimental chamber
A battery pack prototype has been designed and built to evaluate various air cooling concepts for the thermal management of Li-ion batteries. The heat generation from the Li-Ion batteries was simulated with electrical heat generation devices with the same dimensions as the Li-Ion battery (200 mm x 150 mm x 12 mm). Each battery simulator generates up to 15W of heat. There are 20 temperature probes placed uniformly on the surface of the battery simulator, which can measure temperatures in the range from -40 C to +120 C. The prototype for the pack has up to 100 battery simulators and temperature probes are recorder using a PC based DAQ system. We can measure the average surface temperature of the simulator, temperature distribution on each surface and temperature distributions in the pack. The pack which holds the battery simulators is built as a crate, with adjustable gap (varies from 2mm to 5mm) between the simulators for air flow channel studies. The total system flow rate and the inlet flow temperature are controlled during the test. The cooling channel with various heat transfer enhancing devices can be installed between the simulators to investigate the cooling performance. The prototype was designed to configure …
Date:
July 8, 2012
Creator:
A., Lukhanin; U., Rohatgi; Belyaev, A.; Fedorchenko, D.; Khazhmuradov, M.; Lukhanin, O et al.
Object Type:
Article
System:
The UNT Digital Library
Precision Top-Quark Mass Measurements at CDF
We present a precision measurement of the top-quark mass using the full sample of Tevatron {radical}s = 1.96 TeV proton-antiproton collisions collected by the CDF II detector, corresponding to an integrated luminosity of 8.7 fb{sup -1}. Using a sample of t{bar t} candidate events decaying into the lepton+jets channel, we obtain distributions of the top-quark masses and the invariant mass of two jets from the W boson decays from data. We then compare these distributions to templates derived from signal and background samples to extract the top-quark mass and the energy scale of the calorimeter jets with in situ calibration. The likelihood fit of the templates from signal and background events to the data yields the single most-precise measurement of the top-quark mass, mtop = 172.85 {+-} 0.71 (stat) {+-} 0.85 (syst) GeV/c{sup 2}.
Date:
July 1, 2012
Creator:
Aaltonen, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A. et al.
Object Type:
Article
System:
The UNT Digital Library
Measurement of angular correlations of jets at sqrt(s)=1.96 TeV and determination of the strong coupling at high momentum transfers
None
Date:
July 1, 2012
Creator:
Abazov, V. M.
Object Type:
Article
System:
The UNT Digital Library
Response of NSTX Liquid Lithium divertor to High Heat Loads
Samples of the NSTX Liquid Lithium Divertor (LLD) with and without an evaporative Li coating were directly exposed to a neutral beam ex-situ at a power of ~1.5 MW/m2 for 1-3 seconds. Measurements of front face and bulk sample temperature were obtained. Predictions of temperature evolution were derived from a 1D heat flux model. No macroscopic damage occurred when the "bare" sample was exposed to the beam but microscopic changes to the surface were observed. The Li-coated sample developed a lithium hydroxide (LiOH) coating, which did not change even when the front face temperature exceeded the pure Li melting point. These results are consistent with the lack of damage to the LLD surface and imply that heating alone may not expose pure liquid Li if the melting point of surface impurities is not exceeded. This suggests that flow and heat are needed for future PFCs requiring a liquid Li surface. __________________________________________________
Date:
July 18, 2012
Creator:
Abrams, Tyler; Kallman, J; Kaitaa, R; Foley, E L; Grayd, T K; Kugel, H et al.
Object Type:
Article
System:
The UNT Digital Library
ILC RF System R and D
The Linac Group at SLAC is actively pursuing a broad range of R&D to improve the reliability and reduce the cost of the L-band (1.3 GHz) rf system proposed for the ILC linacs. Current activities include the long-term evaluation of a 120 kV Marx Modulator driving a 10 MW Multi-Beam Klystron, design of a second-generation Marx Modulator, testing of a sheet-beam gun and beam transport system for a klystron, construction of an rf distribution system with remotely-adjustable power tapoffs, and development of a system to combine the power from many klystrons in low-loss circular waveguide where it would be tapped-off periodically to power groups of cavities. This paper surveys progress during the past few years.
Date:
July 3, 2012
Creator:
Adolphsen, Chris
Object Type:
Article
System:
The UNT Digital Library
HIGH POWER TEST OF RF SEPARATOR FOR 12 GEV UPGRADE OF CEBAF AT JLAB
CEBAF at JLab is in the process of an energy upgrade from 6 GeV to 12 GeV. The existing setup of the RF separator cavities in the 5th pass will not be adequate to extract the highest energy (11 GeV) beam to any two existing halls (A, B or C) while simultaneously delivering to the new hall D in the case of the proposed 12 GeV upgrade of the machine. To restore this capability, we are exploring the possibility of extension of existing normal conducting 499 MHz TEM-type rf separator cavities. Detailed numerical studies suggest that six 2-cell normal conducting structures meet the requirements; each 2-cell structure will require up to 4 kW RF input power in contrast with the current nominal operating power of 1.0 to 2.0 kW. A high power test of 4 kW confirms that the cavity meet the requirement.
Date:
July 1, 2012
Creator:
Ahmed, S.; Wissmann, M.; Mammosser, J.; Hovater, C.; Spata, M.; Krafft, G. et al.
Object Type:
Article
System:
The UNT Digital Library
Multi Optical Transition Radiation System for ATF2
In this paper we describe the design, installation and first calibration tests of a Multi Optical Transition Radiation System in the beam diagnostic section of the Extraction (EXT) line of ATF2, close to the multi wire scanner system. This system will be a valuable tool for measuring beam sizes and emittances coming from the ATF Damping Ring. With an optical resolution of about 2 {micro}m an original OTR design (OTR1X) located after the septum at the entrance of the EXT line demonstrated the ability to measure a 5.5 {micro}m beam size in one beam pulse and to take many fast measurements. This gives the OTR the ability to measure the beam emittance with high statistics, giving a low error and a good understanding of emittance jitter. Furthermore the nearby wire scanners will be a definitive test of the OTR as a beam emittance diagnostic device. The multi-OTR system design proposed here is based on the existing OTR1X.
Date:
July 13, 2012
Creator:
Alabau-Gonzalvo, Javier; /Valencia U., IFIC; Blanch Gutierrez, Cesar; /Valencia U., IFIC; Civera, Jose Vicente; /Valencia U., IFIC et al.
Object Type:
Article
System:
The UNT Digital Library
Design of Electron and Ion Crabbing Cavities for an Electron-Ion Collider
Beyond the 12 GeV upgrade at the Jefferson Lab a Medium Energy Electron-Ion Collider (MEIC) has been considered. In order to achieve the desired high luminosities at the Interaction Points (IP), the use of crabbing cavities is under study. In this work, we will present to-date designs of superconducting cavities, considered for crabbing both ion and electron bunches. A discussion of properties such as peak surface fields and higher-order mode separation will be presented. Keywords: super conducting, deflecting cavity, crab cavity.
Date:
July 1, 2012
Creator:
Alejandro Castilla Loeza, Geoffrey Krafft, Jean Delayen
Object Type:
Article
System:
The UNT Digital Library
LWR First Recycle of TRU with Thorium Oxide for Transmutation and Cross Sections
Thorium has been considered as an option to uranium-based fuel, based on considerations of resource utilization (thorium is approximately three times more plentiful than uranium) and as a result of concerns about proliferation and waste management (e.g. reduced production of plutonium, etc.). Since the average composition of natural Thorium is dominated (100%) by the fertile isotope Th-232, Thorium is only useful as a resource for breeding new fissile materials, in this case U-233. Consequently a certain amount of fissile material must be present at the start-up of the reactor in order to guarantee its operation. The thorium fuel can be used in both once-through and recycle options, and in both fast and thermal spectrum systems. The present study has been aimed by the necessity of investigating the option of using reprocessed plutonium/TRU, from a once-through reference LEU scenario (50 GWd/ tIHM), mixed with natural thorium and the need of collect data (mass fractions, cross-sections etc.) for this particular fuel cycle scenario. As previously pointed out, the fissile plutonium is needed to guarantee the operation of the reactor. Four different scenarios have been considered: • Thorium – recycled Plutonium; • Thorium – recycled Plutonium/Neptunium; • Thorium – recycled Plutonium/Neptunium/Americium; • Thorium …
Date:
July 1, 2012
Creator:
Alfonsi, Andrea & Youinou, Gilles
Object Type:
Report
System:
The UNT Digital Library
Collaboratory for Multiscale Chemical Science (CMCS)
This document provides details of the contributions made by NIST to the Collaboratory for Multiscale Chemical Science (CMCS) project. In particular, efforts related to the provision of data (and software in support of that data) relevant to the combustion pilot project are described.
Date:
July 3, 2012
Creator:
Allison, Thomas C.
Object Type:
Report
System:
The UNT Digital Library
COMMISSIONING AND OPERATION OF THE CEBAF 100 MV CRYOMODULES
The Continuous Electron Beam Accelerator Facility (CEBAF) energy upgrade from 6 GeV to 12 GeV includes the installation of ten new 100 MV cryomodules and RF systems. The superconducting RF cavities are designed to operate CW at a maximum accelerating gradient of 19.3 MV/m. To support the higher gradients and higher Q{sub L} ({approx} 3 x 10{sup 7}), a new RF system has been developed and is being installed to power and control the cavities. The RF system employs digital control and 13 kW klystrons. Recently, two of these cryomodules and associated RF hardware and software have been installed and commissioned in the CEBAF accelerator. Electrons at linac currents up to 540 {micro}A have been successfully accelerated and used for nuclear physics experiments. This paper reports on the commissioning and operation of the RF system and cryomodules.
Date:
July 1, 2012
Creator:
Allison, Trent; Davis, K.; Drury, Michael; Harwood, Leigh; Hogan, John; Kimber, Andrew et al.
Object Type:
Article
System:
The UNT Digital Library
Design of An 18 MW Beam Dump for 500 GeV Electron/Positron Beams at An ILC
This article presents a report on the progress made in designing 18 MW water based Beam Dumps for electrons or positrons for an International Linear Collider (ILC). Multi-dimensional technology issues have to be addressed for the successful design of the Beam Dump. They include calculations of power deposition by the high energy electron/positron beam bunch trains, computational fluid dynamic analysis of turbulent water flow, mechanical design, process flow analysis, hydrogen/oxygen recombiners, handling of radioactive 7Be and 3H, design of auxiliary equipment, provisions for accident scenarios, remote window exchanger, radiation shielding, etc. The progress made to date is summarized, the current status, and also the issues still to be addressed.
Date:
July 5, 2012
Creator:
Amann, John; /SLAC; Arnold, Ray; /SLAC; Seryi, Andrei; /SLAC et al.
Object Type:
Article
System:
The UNT Digital Library
Wind prediction with multiple guide stars reduces tomographic errors and expands MOAO field of regard
None
Date:
July 12, 2012
Creator:
Ammons, S. M.; Poyneer, L.; Gavel, D.; Kupke, R.; Max, C. E. & Johnson, L.
Object Type:
Article
System:
The UNT Digital Library
Microarcsecond relative astrometry from the ground with a diffractive pupil
None
Date:
July 12, 2012
Creator:
Ammons, S. Mark; Bendek, Eduardo A.; Guyon, Olivier; Macintosh, Bruce & Savransky, Dmitry
Object Type:
Article
System:
The UNT Digital Library
Renewable Energy Certificate Program
This project was primarily to develop and implement a curriculum which will train undergraduate and graduate students at the University seeking a degree as well as training for enrollees in a special certification program to prepare individuals to be employed in a broad range of occupations in the field of renewable energy and energy conservation. Curriculum development was by teams of Saint Francis University Faculty in the Business Administration and Science Departments and industry experts. Students seeking undergraduate and graduate degrees are able to enroll in courses offered within these departments which will combine theory and hands-on training in the various elements of wind power development. For example, the business department curriculum areas include economic modeling, finance, contracting, etc. The science areas include meteorology, energy conversion and projection, species identification, habitat protection, field data collection and analysis, etc.
Date:
July 17, 2012
Creator:
Andersen, Gwendolyn S.
Object Type:
Report
System:
The UNT Digital Library
The Capsule-Fill-Tube-Assembly Mapping System
None
Date:
July 30, 2012
Creator:
Antipa, N. A.
Object Type:
Article
System:
The UNT Digital Library
Summary Report of the INL-JISEA Workshop on Nuclear Hybrid Energy Systems
The Institute for Nuclear Energy Science and Technology (INEST) and the Joint Institute for Strategic Energy Analysis (JISEA) co-sponsored an international workshop to identify research topics important in advancing the potential use of hybrid systems with a specific focus on nuclear-renewable hybrid systems. The workshop included presentations ranging from energy challenges and research and development directions being pursued by nations to multiple options for hybrid systems. Those options include one that is being commercialized to other opportunities and analysis results quantifying them. The workshop also involved two breakout sessions--one focused on thermal energy management issues especially at unit-operation scale and the second focused on system operations issues including system controls, regulatory issues, technical and economic analysis, and market challenges. A discussion involving the full group focused on more general issues such as societal involvement and participation. Key criteria for selecting hybrid energy system projects and metrics for comparing them were also identified by the full group.
Date:
July 1, 2012
Creator:
Antkowiak, M.; Ruth, M.; Boardman, R.; Bragg-Sitton, S.; Cherry, R. & Shunn, L.
Object Type:
Report
System:
The UNT Digital Library
Summary Report of the INL-JISEA Workshop on Nuclear Hybrud Energy Systems
Hybrid energy systems utilize two or more energy resources as inputs to two or more physically coupled subsystems to produce one or more energy commodities as outputs. Nuclear hybrid energy systems can be used to provide load-following electrical power to match diurnal to seasonal-scale changes in power demand or to compensate for the variability of renewable wind or solar generation. To maintain economical, full rate operation of the nuclear reactor, its thermal energy available when power demand is low could be diverted into making synthetic vehicle fuels of various types. The Institute for Nuclear Energy Science and Technology (INEST) and the Joint Institute for Strategic Energy Analysis (JISEA) co-sponsored an international workshop to identify research topics important in advancing the potential use of hybrid systems with a specific focus on nuclear-renewable hybrid systems. The workshop included presentations ranging from energy challenges and research and development (R&D) directions being pursued by nations to multiple options for hybrid systems. Those options include one that is being commercialized to other opportunities and analysis results quantifying them. The workshop also involved two breakout sessions - one focused on thermal energy management issues especially at unit-operation scale and the second focused on system operations issues …
Date:
July 1, 2012
Creator:
Antkowiak, Mark; Boardman, Richard; Bragg-Sitton, Shannon; Cherry, Robert & Ruth, Mark
Object Type:
Report
System:
The UNT Digital Library
Results of the Excreta Bioassay Quality Control Program for April 1, 2009 through March 31, 2010
A total of 58 urine samples and 10 fecal samples were submitted during the report period (April 1, 2009 through March 31, 2010) to General Engineering Laboratories, South Carolina by the Hanford Internal Dosimetry Program (IDP) to check the accuracy, precision, and detection levels of their analyses. Urine analyses for Sr, 238Pu, 239Pu, 241Am, 243Am 235U, 238U, elemental uranium and fecal analyses for 241Am, 238Pu and 239Pu were tested this year as well as four tissue samples for 238Pu, 239Pu, 241Am and 241Pu. The number of QC urine samples submitted during the report period represented 1.3% of the total samples submitted. In addition to the samples provided by IDP, GEL was also required to conduct their own QC program, and submit the results of analyses to IDP. About 33% of the analyses processed by GEL during the third year of this contract were quality control samples. GEL tested the performance of 21 radioisotopes, all of which met or exceeded the specifications in the Statement of Work within statistical uncertainty (Table 4).
Date:
July 19, 2012
Creator:
Antonio, Cheryl L.
Object Type:
Report
System:
The UNT Digital Library
Results of The Excreta Bioassay Quality Control Program For April 1, 2010 Through March 31, 2011
A total of 76 urine samples and 10 spiked fecal samples were submitted during the report period (April 1, 2010 through March 31, 2011) to GEL Laboratories, LLC in South Carolina by the Hanford Internal Dosimetry Program (IDP) to check the accuracy, precision, and detection levels of their analyses. Urine analyses for 14C, Sr, for 238Pu, 239Pu, 241Am, 243Am, 235U, 238U, 238U-mass and fecal analyses for 241Am, 238Pu and 239Pu were tested this year. The number of QC urine samples submitted during the report period represented 1.1% of the total samples submitted. In addition to the samples provided by IDP, GEL was also required to conduct their own QC program, and submit the results of analyses to IDP. About 31% of the analyses processed by GEL during the first year of contract 112512 were quality control samples. GEL tested the performance of 23 radioisotopes, all of which met or exceeded the specifications in the Statement of Work within statistical uncertainty except the slightly elevated relative bias for 243,244Cm (Table 4).
Date:
July 19, 2012
Creator:
Antonio, Cheryl L.
Object Type:
Report
System:
The UNT Digital Library
Refurbishment and Testing of the 1970's Era LASS Solenoid Coils for JLab's Hall D
JLab refurbished the LASS1, 1.85 m bore Solenoid, consisting of four superconducting coils to act as the principal analysis magnet for nuclear physics in the newly constructed, Hall D at Jefferson Lab. The coils, built in 1971 at Stanford Linier Accelerator Center and used a second time at the MEGA Experiment at Los Alamos, had electrical shorts and leaks to the insulating vacuum along with deteriorated superinsulation & instrumentation. Root cause diagnosis of the problems and the repair methods are described along with the measures used to qualify the vessels and piping within the Laboratory's Pressure Safety Program (mandated by 10CFR851). The extraordinary refrigerator operational methods used to utilize the obsolete cryogenic apparatus gathered for the off-line, single coil tests are described.
Date:
July 1, 2012
Creator:
Anumagalla, Ravi; Biallas, George; Brindza, Paul; Carstens, Thomas; Creel, Jonathan; Egiyan, Hovanes et al.
Object Type:
Article
System:
The UNT Digital Library