Biochemistry of Ammonia Monoxygenase from Nitrosomonas (open access)

Biochemistry of Ammonia Monoxygenase from Nitrosomonas

Major results. 1. CytochromecM552, a protein in the electron transfer chain to ammonia monooxygenase. Purification, modeling of protein structure based on primary structure, characterization of 4 hemes by magnetic spectroscopy, potentiometry, ligand binding and turnover. Kim, H. J., ,Zatsman, et al. 2008). 2. Characterization of proteins which thought to be involved in the AMO reaction or to protect AMO from toxic nitrogenous intermediates such as NO. Nitrosocyanin is a protein present only in bacteria which catalyze the ammonia monoxygenase reaction (1). Cytochrome c P460 beta and cytochrome c’ beta.
Date: July 15, 2009
Creator: Hooper, Alan
Object Type: Report
System: The UNT Digital Library
Radiation Chemistry 2008 Gordon Research Conference - July 6-11, 2008 (open access)

Radiation Chemistry 2008 Gordon Research Conference - July 6-11, 2008

Radiation Chemistry is chemistry initiated by ionizing radiation: i.e. photons or particles with energy sufficient to create charge pairs and/or free radicals in a medium. The important transients include conduction band electrons and 'holes', excitons, ionic and neutral free radicals, highly excited states, and solvated electrons. Effects of radiation span timescales from the energy deposition in femtoseconds, through geminate recombination in picoseconds and nanoseconds, to fast radical chemistry in microseconds and milliseconds, and ultimately to processes like cancer occurring decades later. The radiation sources used to study these processes likewise run from femtosecond lasers to nanosecond accelerators to years of gamma irradiation. As a result the conference has a strong interdisciplinary flavor ranging from fundamental physics to clinical biology. While the conference focuses on fundamental science, application areas highlighted in the present conference will include nuclear power, polymer processing, and extraterrestrial chemistry.
Date: May 15, 2009
Creator: Bartels, David M.
Object Type: Article
System: The UNT Digital Library
Long-term monitoring of fleshy fruit and hard mast production and seasonal bird distribution at the Savannah River Site, South Carolina. (open access)

Long-term monitoring of fleshy fruit and hard mast production and seasonal bird distribution at the Savannah River Site, South Carolina.

A final report of Fruit and hard mast production in five habitat types at SRS with a comparison of fruit consumption by fledgling versus adult birds at SRS and Relative importance of fruit, seeds, and insects in the diets of overwintering birds at SRS.
Date: June 15, 2009
Creator: Greenberg, Cathryn, H. & Levey, Douglas J.
Object Type: Report
System: The UNT Digital Library
Hanford Site Environmental Report for Calendar Year 2008 (open access)

Hanford Site Environmental Report for Calendar Year 2008

The Hanford Site environmental report is prepared annually for the U.S. Department of Energy (DOE) in accordance with regulatory requirements. The report provides an overview of activities at the Hanford Site; demonstrates the status of the site’s compliance with applicable federal, state, and local environmental laws and regulations, executive orders, and DOE policies and directives; and summarizes environmental data that characterize Hanford Site environmental management performance. The report also highlights significant environmental and public protection programs and efforts. Some historical and early 2009 information is included where appropriate.
Date: September 15, 2009
Creator: Poston, Ted M.; Duncan, Joanne P. & Dirkes, Roger L.
Object Type: Report
System: The UNT Digital Library
Atmospheric Radiation Measurement program climate research facility operations quarterly report October 1 - December 31, 2008. (open access)

Atmospheric Radiation Measurement program climate research facility operations quarterly report October 1 - December 31, 2008.

Individual raw data streams from instrumentation at the Atmospheric Radiation Measurement (ARM) Program Climate Research Facility (ACRF) fixed and mobile sites are collected and sent to the Data Management Facility (DMF) at Pacific Northwest National Laboratory (PNNL) for processing in near real-time. Raw and processed data are then sent daily to the ACRF Archive, where they are made available to users. For each instrument, they calculate the ratio of the actual number of data records received daily at the Archive to the expected number of data records. The results are tabulated by (1) individual data stream, site, and month for the current year and (2) site and fiscal year (FY) dating back to 1998. The US Department of Energy (DOE) requires national user facilities to report time-based operating data. The requirements concern the actual hours of operation (ACTUAL); the estimated maximum operation or uptime goal (OPSMAX), which accounts for planned downtime; and the VARIANCE [1-(ACTUAL/OPSMAX)], which accounts for unplanned downtime. The OPSMAX time for the first quarter of FY 2009 for the Southern Great Plains (SGP) site is 2,097.60 hours (0.95 x 2,208 hours this quarter). The OPSMAX for the North Slope Alaska (NSA) locale is 1,987.20 hours (0.90 x …
Date: January 15, 2009
Creator: Sisterson, D. L.
Object Type: Report
System: The UNT Digital Library
On Possible Interpretations of the High Energy Electron-Positron Spectrum Measured by the Fermi Large Area Telescope (open access)

On Possible Interpretations of the High Energy Electron-Positron Spectrum Measured by the Fermi Large Area Telescope

The Fermi-LAT experiment recently reported high precision measurements of the spectrum of cosmic-ray electrons-plus-positrons (CRE) between 20 GeV and 1 TeV. The spectrum shows no prominent spectral features, and is significantly harder than that inferred from several previous experiments. Here we discuss several interpretations of the Fermi results based either on a single large scale Galactic CRE component or by invoking additional electron-positron primary sources, e.g. nearby pulsars or particle Dark Matter annihilation. We show that while the reported Fermi-LAT data alone can be interpreted in terms of a single component scenario, when combined with other complementary experimental results, specifically the CRE spectrum measured by H.E.S.S. and especially the positron fraction reported by PAMELA between 1 and 100 GeV, that class of models fails to provide a consistent interpretation. Rather, we find that several combinations of parameters, involving both the pulsar and dark matter scenarios, allow a consistent description of those results. We also briefly discuss the possibility of discriminating between the pulsar and dark matter interpretations by looking for a possible anisotropy in the CRE flux.
Date: May 15, 2009
Creator: Grasso, D.; Profumo, S.; Strong, A.W.; Baldini, L.; Bellazzini, R.; Bloom, E.D. et al.
Object Type: Report
System: The UNT Digital Library
Snake River Fall Chinook Salmon Life History Investigations, Annual Report 2008. (open access)

Snake River Fall Chinook Salmon Life History Investigations, Annual Report 2008.

This study was initiated to provide empirical data and analyses on the dam passage timing, travel rate, survival, and life history variation of fall Chinook salmon that are produced in the Clearwater River. The area of interest for this study focuses on the lower four miles of the Clearwater River and its confluence with the Snake River because this is an area where many fish delay their seaward migration. The goal of the project is to increase our understanding of the environmental and biological factors that affect juvenile life history of fall Chinook salmon in the Clearwater River. The following summaries are provided for each of the individual chapters in this report.
Date: September 15, 2009
Creator: Tiffan, Kenneth F.; Connor, William P. & Bellgraph, Brian J.
Object Type: Report
System: The UNT Digital Library
Impact of phenolic substrate and growth temperature on the arthrobacter chlorophenolicus proteome (open access)

Impact of phenolic substrate and growth temperature on the arthrobacter chlorophenolicus proteome

We compared the Arthrobacter chlorophenolicus proteome during growth on 4-chlorophenol, 4-nitrophenol or phenol at 5 C and 28 C; both for the wild type and a mutant strain with mass spectrometry based proteomics. A label free workflow employing spectral counting identified 3749 proteins across all growth conditions, representing over 70% of the predicted genome and 739 of these proteins form the core proteome. Statistically significant differences were found in the proteomes of cells grown under different conditions including differentiation of hundreds of unknown proteins. The 4-chlorophenol-degradation pathway was confirmed, but not that for phenol.
Date: February 15, 2009
Creator: Unell, Maria; Abraham, Paul E.; Shah, Manesh; Zhang, Bing; Ruckert, Christian; VerBerkmoes, Nathan C. et al.
Object Type: Article
System: The UNT Digital Library
Hanford Site Near-Facility Environmental Monitoring Data Report for Calendar Year 2008 (open access)

Hanford Site Near-Facility Environmental Monitoring Data Report for Calendar Year 2008

Near-facility environmental monitoring is defined as monitoring near facilities that have the potential to discharge or have discharged, stored, or disposed of radioactive or hazardous materials. Monitoring locations are associated with nuclear facilities such as the Plutonium Finishing Plant, Canister Storage Building, and the K Basins; inactive nuclear facilities such as N Reactor and the Plutonium-Uranium Extraction (PUREX) Facility; and waste storage or disposal facilities such as burial grounds, cribs, ditches, ponds, tank farms, and trenches. Much of the monitoring consists of collecting and analyzing environmental samples and methodically surveying areas near facilities. The program is also designed to evaluate acquired analytical data, determine the effectiveness of facility effluent monitoring and controls, assess the adequacy of containment at waste disposal units, and detect and monitor unusual conditions.
Date: September 15, 2009
Creator: Perkins, Craig J.; Dorsey, Michael C.; Mckinney, Stephen M.; Wilde, Justin W. & Poston, Ted M.
Object Type: Report
System: The UNT Digital Library
Observed 1970-2005 cooling of summer daytime temperatures in coastal California (open access)

Observed 1970-2005 cooling of summer daytime temperatures in coastal California

The study evaluated 1948-2004 summer (JJA) mean monthly air temperatures for two California air basins: SoCAB and SFBA. The study focuses on the more rapid post-1970 warming period, and its daily T{sub min} and T{sub max} values were used to produce average monthly values and spatial distributions of trends for each air basins. Additional analyses included T{sub D} values at two NWS sites, SSTs, NCEP reanalysis sea-level pressures, and GCM T{sub ave}-values. Results for all California COOP sites together showed increased JJA T{sub ave}-values; asymmetric warming, as T{sub min}-values increase faster than T{sub max}-values; and thus decreased DTR values. The spatial distribution of observed SoCAB and SFBA T{sub max} values exhibited a complex pattern, with cooling in low-elevation coastal-areas open to marine air penetration and warming at inland areas. Results also showed that decreased DTR values in the valleys arose from small increases at 'inland' sites combined with large decreases at 'coastal' sites. Previous studies suggest that cooling JJA T{sub max}-values in coastal California were due to increased irrigation, coastal upwelling, or cloud cover, while the current hypothesis is that they arises from GHG-induced global-warming of 'inland' areas, which results in increased sea breeze flow activity. Sea level pressure trends …
Date: May 15, 2009
Creator: Lebassi, B.; Gonzalez, J.; Fabris, D.; Maurer, E.; Miller, N.; Milesi, C. et al.
Object Type: Article
System: The UNT Digital Library
Country Report on Building Energy Codes in Japan (open access)

Country Report on Building Energy Codes in Japan

This report is part of a series of reports on building energy efficiency codes in countries associated with the Asian Pacific Partnership (APP) - Australia, South Korea, Japan, China, India, and the United States of America (U.S.). This reports gives an overview of the development of building energy codes in Japan, including national energy policies related to building energy codes, history of building energy codes, recent national projects and activities to promote building energy codes. The report also provides a review of current building energy codes (such as building envelope, HVAC, and lighting) for commercial and residential buildings in Japan.
Date: April 15, 2009
Creator: Evans, Meredydd; Shui, Bin & Takagi, T.
Object Type: Report
System: The UNT Digital Library
Environmental Management Waste Management Facility Waste Lot Profile for the K-770 Scrap Yard Soils and Miscellaneous Debris, East Tennessee Technology Park, Oak Ridge, Tennessee - EMWMF Waste Lot 4.12 (open access)

Environmental Management Waste Management Facility Waste Lot Profile for the K-770 Scrap Yard Soils and Miscellaneous Debris, East Tennessee Technology Park, Oak Ridge, Tennessee - EMWMF Waste Lot 4.12

Waste Lot 4.12 consists of approximately 17,500 yd{sup 3} of low-level, radioactively contaminated soil, concrete, and incidental metal and debris generated from remedial actions at the K-770 Scrap Metal Yard and Contaminated Debris Site (the K-770 Scrap Yard) at the East Tennessee Technology Park (ETTP). The excavated soil will be transported by dump truck to the Environmental Management Waste Management Facility (EMWMF). This profile provides project-specific information to demonstrate compliance with Attainment Plan for Risk/Toxicity-based Waste Acceptance Criteria at the Oak Ridge Reservation, Oak Ridge, Tennessee (DOE 2001). The K-770 Scrap Yard is an approximately 36-acre storage area located southwest of the main portion of ETTP, outside the security perimeter fence in the Powerhouse Area adjacent to the Clinch River. The K-770 area was used to store radioactively contaminated or suspected contaminated materials during and previous to the K-25 Site cascade upgrading program. The waste storage facility began operation in the 1960s and is estimated to at one time contain in excess of 40,000 tons of low-level, radioactively contaminated scrap metal. Scrap metal was taken to the site when it was found to contain alpha or beta/gamma activity on the surface or if the scrap metal originated from a process …
Date: April 15, 2009
Creator: M., Davenport
Object Type: Report
System: The UNT Digital Library
Control Banding and Nanotechnology Synergist (open access)

Control Banding and Nanotechnology Synergist

The average Industrial Hygienist (IH) loves a challenge, right? Okay, well here is one with more than a few twists. We start by going through the basics of a risk assessment. You have some chemical agents, a few workers, and the makings of your basic exposure characterization. However, you have no occupational exposure limit (OEL), essentially no toxicological basis, and no epidemiology. Now the real handicap is that you cannot use sampling pumps, cassettes, tubes, or any of the media in your toolbox, and the whole concept of mass-to-dose is out the window, even at high exposure levels. Of course, by the title, you knew we were talking about nanomaterials (NM). However, we wonder how many IHs know that this topic takes everything you know about your profession and turns it upside down. It takes the very foundations that you worked so hard in college and in the field to master and pulls it out from underneath you. It even takes the gold standard of our profession, the quantitative science of exposure assessment, and makes it look pretty darn rusty. Now with NM there is the potential to get some aspect of quantitative measurements, but the instruments are generally very …
Date: December 15, 2009
Creator: Zalk, D & Paik, S
Object Type: Article
System: The UNT Digital Library
Longitudinal Bunch Position Control for the Super-B Accelerator (open access)

Longitudinal Bunch Position Control for the Super-B Accelerator

The use of normal conducting cavities and an ion-clearing gap will cause a significant RF accelerating voltage gap transient and longitudinal phase shift of the individual bunches along the bunch train in both rings of the SuperB accelerator. Small relative centroid position shifts between bunches of the colliding beams will have a large adverse impact on the luminosity due to the small {beta}*{sub y} at the interaction point (IP). We investigate the possibility of minimizing the relative longitudinal position shift between bunches by reducing the gap transient in each ring and matching the longitudinal bunch positions of the two rings at the IP using feedback/feedforward techniques in the LLRF. The analysis is conducted assuming maximum use of the klystron power installed in the system.
Date: May 15, 2009
Creator: Bertsche, Kirk; Rivetta, Claudio; Sullivam, Michael K. & Drago, Alessandro
Object Type: Article
System: The UNT Digital Library
Variation in soil moisture and N availability modulates carbon and water exchange in a California grassland experiment (open access)

Variation in soil moisture and N availability modulates carbon and water exchange in a California grassland experiment

Variability in the magnitude and timing of precipitation is predicted to change under future climate scenarios. The primary objective of this study was to understand how variation in precipitation patterns consisting of soil moisture pulses mixed with intermittent dry down events influence ecosystem gas fluxes. We characterized the effects of precipitation amount and timing, N availability, and plant community composition on whole ecosystem and leaf gas exchange in a California annual grassland mesocosm study system that allowed precise control of soil moisture conditions. Ecosystem CO2 and fluxes increased significantly with greater precipitation and were positively correlated with soil moisture. A repeated 10 day dry down period following 11 days of variable precipitation inputs strongly depressed net ecosystem CO2 exchange (NEE) across a range of season precipitation totals, and plant community types. Ecosystem respiration (Re), evapotranspiration (ET) and leaf level photosynthesis (Amax) showed greatest sensitivity to dry down periods in low precipitation plots. Nitrogen additions significantly increased NEE, Re and Amax, particularly as water availability was increased. These results demonstrate that N availability and intermittent periods of soil moisture deficit (across a wide range of cumulative season precipitation totals) strongly modulate ecosystem gas exchange.
Date: March 15, 2009
Creator: Clair, S.B., St.; Sudderth, E.; Fischer, M. L.; Torn, M. S.; Stuart, S.; Salve, R. et al.
Object Type: Article
System: The UNT Digital Library
Production of the Smallest QED Atom: True Muonium (open access)

Production of the Smallest QED Atom: True Muonium

The 'true muonium' ({mu}{sup +}{mu}{sup -}) and 'true tauonium' ({tau}{sup +}{tau}{sup -}) bound states are not only the heaviest, but also the most compact pure QED systems. The rapid weak decay of the {tau} makes the observation of true tauonium difficult. However, as we show, the production and study of true muonium is possible at modern electron-positron colliders.
Date: April 15, 2009
Creator: Brodsky, Stanley J. & Lebed, Richard F.
Object Type: Article
System: The UNT Digital Library
TEM Study of Oxide Nanoparticles in ODS Steels Developed for Radiation Tolerance (open access)

TEM Study of Oxide Nanoparticles in ODS Steels Developed for Radiation Tolerance

None
Date: October 15, 2009
Creator: Hsiung, L; Fluss, M; Kuntz, J; El-Dasher, B; Choi, W; Tumey, S J et al.
Object Type: Article
System: The UNT Digital Library
WASTE PROCESSING ANNUAL NUCLEAR SAFETY RELATED R AND D REPORT FOR CY2008 (open access)

WASTE PROCESSING ANNUAL NUCLEAR SAFETY RELATED R AND D REPORT FOR CY2008

The Engineering and Technology Office of Waste Processing identifies and reduces engineering and technical risks associated with key waste processing project decisions. The risks, and actions taken to mitigate those risks, are determined through technology readiness assessments, program reviews, technology information exchanges, external technical reviews, technical assistance, and targeted technology development and deployment (TDD). The Office of Waste Processing TDD program prioritizes and approves research and development scopes of work that address nuclear safety related to processing of highly radioactive nuclear wastes. Thirteen of the thirty-five R&D approved work scopes in FY2009 relate directly to nuclear safety, and are presented in this report.
Date: October 15, 2009
Creator: Fellinger, A.
Object Type: Report
System: The UNT Digital Library
Cometabolic bioremediation (open access)

Cometabolic bioremediation

Cometabolic bioremediation is probably the most under appreciated bioremediation strategy currently available. Cometabolism strategies stimulate only indigenous microbes with the ability to degrade the contaminant and cosubstrate e.g. methane, propane, toluene and others. This highly targeted stimulation insures that only those microbes that can degrade the contaminant are targeted, thus reducing amendment costs, well and formation plugging, etc. Cometabolic bioremediation has been used on some of the most recalcitrant contaminants, e.g. PCE, TCE, MTBE, TNT, dioxane, atrazine, etc. Methanotrophs have been demonstrated to produce methane monooxygense, an oxidase that can degrade over 300 compounds. Cometabolic bioremediation also has the advantage of being able to degrade contaminants to trace concentrations, since the biodegrader is not dependent on the contaminant for carbon or energy. Increasingly we are finding that in order to protect human health and the environment that we must remediate to lower and lower concentrations, especially for compounds like endocrine disrupters, thus cometabolism may be the best and maybe the only possibility that we have to bioremediate some contaminants.
Date: February 15, 2009
Creator: Hazen, Terry C.
Object Type: Book
System: The UNT Digital Library
Ion distributions at charged aqueous surfaces: Synchrotron X-ray scattering studies (open access)

Ion distributions at charged aqueous surfaces: Synchrotron X-ray scattering studies

Surface sensitive synchrotron X-ray scattering studies were performed to obtain the distribution of monovalent ions next to a highly charged interface at room temperature. To control surface charge density, lipids, dihexadecyl hydrogen-phosphate (DHDP) and dimysteroyl phosphatidic acid (DMPA), were spread as monolayer materials at the air/water interface, containing CsI at various concentrations. Five decades in bulk concentrations (CsI) are investigated, demonstrating that the interfacial distribution is strongly dependent on bulk concentration. We show that this is due to the strong binding constant of hydronium H3O+ to the phosphate group, leading to proton-transfer back to the phosphate group and to a reduced surface charge. Using anomalous reflectivity off and at the L3 Cs+ resonance, we provide spatial counterion (Cs+) distributions next to the negatively charged interfaces. The experimental ion distributions are in excellent agreement with a renormalized surface charge Poisson-Boltzmann theory for monovalent ions without fitting parameters or additional assumptions. Energy Scans at four fixed momentum transfers under specular reflectivity conditions near the Cs+ L3 resonance were conducted on 10-3 M CsI with DHDP monolayer materials on the surface. The energy scans exhibit a periodic dependence on photon momentum transfer. The ion distributions obtained from the analysis are in excellent agreement …
Date: August 15, 2009
Creator: Bu, Wei
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Tunable Tensor Voting Improves Grouping of Membrane-Bound Macromolecules (open access)

Tunable Tensor Voting Improves Grouping of Membrane-Bound Macromolecules

Membrane-bound macromolecules are responsible for structural support and mediation of cell-cell adhesion in tissues. Quantitative analysis of these macromolecules provides morphological indices for damage or loss of tissue, for example as a result of exogenous stimuli. From an optical point of view, a membrane signal may have nonuniform intensity around the cell boundary, be punctate or diffused, and may even be perceptual at certain locations along the boundary. In this paper, a method for the detection and grouping of punctate, diffuse curvilinear signals is proposed. Our work builds upon the tensor voting and the iterative voting frameworks to propose an efficient method to detect and refine perceptually interesting curvilinear structures in images. The novelty of our method lies on the idea of iteratively tuning the tensor voting fields, which allows the concentration of the votes only over areas of interest. We validate the utility of our system with synthetic and annotated real data. The effectiveness of the tunable tensor voting is demonstrated on complex phenotypic signals that are representative of membrane-bound macromolecular structures.
Date: April 15, 2009
Creator: Loss, Leandro A.; Bebis, George & Parvin, Bahram
Object Type: Article
System: The UNT Digital Library
Compact Graph Representations and Parallel Connectivity Algorithms for Massive Dynamic Network Analysis (open access)

Compact Graph Representations and Parallel Connectivity Algorithms for Massive Dynamic Network Analysis

Graph-theoretic abstractions are extensively used to analyze massive data sets. Temporal data streams from socioeconomic interactions, social networking web sites, communication traffic, and scientific computing can be intuitively modeled as graphs. We present the first study of novel high-performance combinatorial techniques for analyzing large-scale information networks, encapsulating dynamic interaction data in the order of billions of entities. We present new data structures to represent dynamic interaction networks, and discuss algorithms for processing parallel insertions and deletions of edges in small-world networks. With these new approaches, we achieve an average performance rate of 25 million structural updates per second and a parallel speedup of nearly28 on a 64-way Sun UltraSPARC T2 multicore processor, for insertions and deletions to a small-world network of 33.5 million vertices and 268 million edges. We also design parallel implementations of fundamental dynamic graph kernels related to connectivity and centrality queries. Our implementations are freely distributed as part of the open-source SNAP (Small-world Network Analysis and Partitioning) complex network analysis framework.
Date: February 15, 2009
Creator: Madduri, Kamesh & Bader, David A.
Object Type: Article
System: The UNT Digital Library
INVESTIGATION OF THE POTENTIAL FOR CAUSTIC STRESS CORROSION CRACKING OF A537 CARBON STEEL NUCLEAR WASTE TANKS (open access)

INVESTIGATION OF THE POTENTIAL FOR CAUSTIC STRESS CORROSION CRACKING OF A537 CARBON STEEL NUCLEAR WASTE TANKS

The evaporator recycle streams contain waste in a chemistry and temperature regime that may be outside of the current waste tank corrosion control program, which imposes temperature limits to mitigate caustic stress corrosion cracking (CSCC). A review of the recent service history (1998-2008) of Tanks 30 and 32 showed that these tanks were operated in highly concentrated hydroxide solution at high temperature. Visual inspections, experimental testing, and a review of the tank service history have shown that CSCC has occurred in uncooled/un-stress relieved F-Area tanks. Therefore, for the Type III/IIIA waste tanks the efficacy of the stress relief of welding residual stress is the only corrosion-limiting mechanism. The objective of this experimental program is to test carbon steel small scale welded U-bend specimens and large welded plates (12 x 12 x 1 in.) in a caustic solution with upper bound chemistry (12 M hydroxide and 1 M each of nitrate, nitrite, and aluminate) and temperature (125 C). These conditions simulate worst-case situations in Tanks 30 and 32. Both as-welded and stress-relieved specimens have been tested. No evidence of stress corrosion cracking was found in the U-bend specimens after 21 days of testing. The large plate test is currently in progress, …
Date: October 15, 2009
Creator: Lam, P.
Object Type: Report
System: The UNT Digital Library
Application of Non-Linear Time-Domain RF Simulations to Longitudinal Emittance Studies for the LHC (open access)

Application of Non-Linear Time-Domain RF Simulations to Longitudinal Emittance Studies for the LHC

A non-linear time-domain simulation has been developed that can determine technical limitations, effects of non-linearities and imperfections, and impact of additive noise on the interaction of the beam with the Impedance Control Radio Frequency (RF) systems [1]. We present a formalism for the extraction of parameters from the time domain simulation to determine the sensitivity of the beam longitudinal emittance and dilution on the RF system characteristics. Previous studies [2], [3] have estimated the effect of a noise source on the beam characteristics assuming an independent perturbation source of the RF voltage and a simplified beam model with no coupling. We present the methodology for the time-domain simulation study of the dependence of the accelerating voltage noise spectrum on the various RF parameters and the technical properties (such as non-linearities, thermal noise, frequency response etc.) of the Low Level RF (LLRF) system components. Future plans to expand this formalism to coupled bunch studies of longitudinal emittance growth in the LHC at nominal and upgraded beam currents are briefly summarized.
Date: May 15, 2009
Creator: Mastorides, T.; Rivetta, C.; Fox, J.D. & Winkle, D.Van
Object Type: Article
System: The UNT Digital Library