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Epicyclic Twin-helix Magnetic Structure for Parametric-resonance Ionization Cooling
ParaÂmetÂric-resÂoÂnance IonÂizaÂtion CoolÂing (PIC) is enÂviÂsioned as the final 6D coolÂing stage of a high-luÂmiÂnosÂiÂty muon colÂlidÂer. ImÂpleÂmentÂing PIC imÂposÂes strinÂgent conÂstraints on the coolÂing chanÂnel's magÂnetÂic opÂtics deÂsign. This paper preÂsents a linÂear opÂtics soÂluÂtion comÂpatÂiÂble with PIC. Our soÂluÂtion conÂsists of a suÂperÂpoÂsiÂtion of two opÂpoÂsite-heÂlicÂiÂty equal-peÂriÂod and equal-strength heÂliÂcal dipole harÂmonÂics and a straight norÂmal quadrupole. We demonÂstrate that such a sysÂtem can be adÂjustÂed to meet all of the PIC linÂear opÂtics reÂquireÂments while reÂtainÂing large acÂcepÂtance.
Date:
May 1, 2010
Creator:
A. Afanasev, R.P. Johnson, Y.S. Derbenev, V.S. Morozov
Object Type:
Article
System:
The UNT Digital Library
Progress of Bep Treatments on Nb at JLAB
Recent experimental results have indicated that Buffered Electropolishing (BEP) is a promising candidate for the next generation of surface treatment technique for Nb superconducting radio frequency (SRF) cavities to be used in particle accelerators. In order to lay the foundation for using BEP as the next generation surface treatment technique for Nb SRF cavities, some fundamental aspects of BEP treatments for Nb have to be investigated. In this report, recent progress on BEP study at JLab is shown. Improvements on the existing vertical BEP are made to allow water cooling from outside of a Nb single cell cavity in addition to cooling provided by acid circulation so that the temperature of the cavity can be stable during processing. Some investigation on the electrolyte mixture was performed to check the aging effect of the electrolyte. It is shown that good polishing results can still be obtained on Nb at a current density of 171 mA/cm when the BEP electrolyte was at the stationary condition and was more than 1.5 years old.
Date:
May 1, 2010
Creator:
A.T. Wu, S. Jin, R.A. Rimmer,X.Y. Lu, K. Zhao
Object Type:
Article
System:
The UNT Digital Library
Combined Tevatron upper limit on gg -> H -> W^+W^- and constraints on the Higgs boson mass in fourth-generation fermion models
We combine results from searches by the CDF and D0 collaborations for a standard model Higgs boson (H) in the process gg {yields} H {yields} W{sup +}W{sup -} in p{bar p} collisions at the Fermilab Tevatron Collider at {radical}s = 1.o6 TeV. With 4.8 fb{sup -1} of itnegrated luminosity analyzed at CDF and 5.4 fb{sup -1} at D0, the 95% Confidence Level upper limit on {sigma}(gg {yields} H) x {Beta}(H {yields} W{sup +}W{sup -}) is 1.75 pb at m{sub H} = 120 GeV, 0.38 pb at m{sub H} = 165 GeV, and 0.83 pb at m{sub H} = 200 GeV. Assuming the presence of a fourth sequential generation of fermions with large masses, they exclude at the 95% Confidence Level a standard-model-like Higgs boson with a mass between 131 and 204 Gev.
Date:
May 1, 2010
Creator:
Aaltonen, T.; Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M. et al.
Object Type:
Article
System:
The UNT Digital Library
Search for the Production of Scalar Bottom Quarks in $p \bar {p} $ collisions at $\sqrt{s} $ = 1.96 TeV
We report on a search for direct scalar bottom quark (sbottom) pair production in p{bar p} collisions at {radical}s = 1.96 TeV, in events with large missing transverse energy and two jets of hadrons in the final state, where at least one of the jets is required to be identified as originating from a b quark. The study uses a CDF Run II data sample corresponding to 2.65 fb{sup -1} of integrated luminosity. The data are in agreement with the standard model. In an R-parity conserving minimal supersymmetric scenario, and assuming that the sbottom decays exclusively into a bottom quark and a neutralino, 95% confidence-level upper limits on the sbottom pair production cross section of 0.1 pb are obtained. For neutralino masses below 70 GeV/c{sup 2}, sbottom masses up to 230 GeV/c{sup 2} are excluded at 95% confidence level.
Date:
May 1, 2010
Creator:
Aaltonen, T.; Phys., /Helsinki Inst. of; Adelman, J.; /Chicago U., EFI; Alvarez Gonzalez, B.; Phys., /Cantabria Inst. of et al.
Object Type:
Article
System:
The UNT Digital Library
Evidence for an anomalous like-sign dimuon charge asymmetry
We measure the charge asymmetry A of like-sign dimuon events in 6.1 fb{sup -1} of p{bar p} collisions recorded with the DO detector at a center of mass energy sqrt s = 1.96 TeV at the Fermilab Tevatron Collider.
Date:
May 1, 2010
Creator:
Abazov, Victor Mukhamedovich; /Dubna, JINR; Abbott, Braden Keim; U., /Oklahoma; Abolins, Maris A.; U., /Michigan State et al.
Object Type:
Article
System:
The UNT Digital Library
Search for scalar bottom quarks and third-generation leptoquarks in p p-bar collisions at sqrt(s) = 1.96 TeV
We report the results of a search for pair production of scalar bottom quarks ({tilde b}{sub 1}) and scalar third-generation leptoquarks (LQ{sub 3}) in 5.2 fb{sup -1} of p{bar p} collisions at the D0 experiment of the Fermilab Tevatron Collider. Scalar bottom quarks are assumed to decay to a neutralino ({tilde {chi}}{sub 1}{sup 0}) and a b quark, and we set 95% C.L. lower limits on their production in the (m{sub {tilde b}{sub 1}}, m{sub {tilde {chi}}{sub 1}{sup 0}}) mass plane such as m{sub {tilde b}{sub 1}} > 247 GeV for m{sub {tilde {chi}}{sub 1}{sup 0}} = 0 and m{sub {tilde {chi}}{sub 1}{sup 0}} > 110 GeV for 160 < m{sub {tilde b}{sub 1}} < 200 GeV. The leptoquarks are assumed to decay to a tau neutrino and a b quark, and we set a 95% C.L. lower limit of 247 GeV on the mass of a charge-1/3 third-generation scalar leptoquark.
Date:
May 1, 2010
Creator:
Abazov, Victor Mukhamedovich; Abbott, Braden Keim; Abolins, Maris A.; Acharya, Bannanje Sripath; Adams, Mark Raymond; Adams, Todd et al.
Object Type:
Article
System:
The UNT Digital Library
INDEPENDENT VERIFICATION SURVEY REPORT FOR THE OPERABLE UNIT-1 LANDFILL TRENCHES, MIAMISBURG CLOSURE PROJECT
INDEPENDENT VERIFICATION SURVEY REPORT FOR THE OPERABLE UNIT-1 LANDFILL TRENCHES, MIAMISBURG CLOSURE PROJECT, MIAMISBURG, OHIO DCN: 0468-SR-02-0
Date:
May 24, 2010
Creator:
Adams, W. C.
Object Type:
Report
System:
The UNT Digital Library
Design Methodology and Consideratios for NOVA 53 MHZ RF Cavities
The NO?A Experiment will construct a detector optimized for electron neutrino detection in the existing Neutrino at Main Injector (NuMI) beamline. This beamline is capable of operating at 400 kW of primary beam power and the upgrade will allow up to 700 kW. The cavities will operate at 53 MHz and three of them will be installed in the Recycler beamline. Thermal stability of the cavities is crucial since this affects the tuning. Results of finite element thermal and structural analysis involving the copper RF cavity will be presented.
Date:
May 19, 2010
Creator:
Ader, C. & Wildman, D.W.
Object Type:
Article
System:
The UNT Digital Library
Mechanical design of ceramic beam tube braze joints for NOVA kicker magnets
The NO?A Experiment will construct a detector optimized for electron neutrino detection in the existing NuMI neutrino beam. The NuMI beam line is capable of operating at 400 kW of primary beam power and the upgrade will allow up to 700 kW. Ceramic beam tubes are utilized in numerous kicker magnets in different accelerator rings at Fermi National Accelerator Laboratory. Kovar flanges are brazed onto each beam tube end, since kovar and high alumina ceramic have similar expansion curves. The tube, kovar flange, end piece, and braze foil alloy brazing material are stacked in the furnace and then brazed. The most challenging aspect of fabricating kicker magnets in recent years have been making hermetic vacuum seals on the braze joints between the ceramic and flange. Numerous process variables can influence the robustness of conventional metal/ceramic brazing processes. The ceramic-filler metal interface is normally the weak layer when failure does not occur within the ceramic. Differences between active brazing filler metal and the moly-manganese process will be discussed along with the applicable results of these techniques used for Fermilab production kicker tubes.
Date:
May 1, 2010
Creator:
Ader, C. R.; Reilly, R. E. & Wilson, J. H.
Object Type:
Article
System:
The UNT Digital Library
Linear and chromatic optics measurements at RHIC
Measurements of chromatic beta-beating were carried out for the first time in the RHIC accelerator during Run 2009. The analysis package developed for the LHC was used to extract the off-momentum optics for injection and top energy. Results from the beam experiments and compassion to the optics model are presented. The primary goal of the RHIC experiments were execute an on-line measurement of the optics using the tools developed for the LHC. Turn-by-turn BPM trajectories (typically 1000 turns) acquired immediately after an external dipole kick are numerically analyzed to determine the optical parameters at the location of the beam position monitors (BPMs). For chromatic optics, a similar analysis, but on a beam with finite momentum offset(s). Each optical measurement typically is calculated from multiple data sets to capture statistical variations and ensure reproducibility. The procedure of measurement and analysis is detailed in ref [1, 2]. Two dedicated experiments were performed at RHIC with protons during Run 2009. The first at injection energy and optics and the other at 250 GeV and squeezed optics. The basic RHIC parameters relevant for the two experiments are listed in Table 1.
Date:
May 23, 2010
Creator:
Aiba, M.; Calaga, R.; Aiba, M.; Tomas, R. & Vanbavinkove, G.
Object Type:
Article
System:
The UNT Digital Library
Silicon Detector Letter of Intent
This document presents the current status of SiD's effort to develop an optimized design for an experiment at the International Linear Collider. It presents detailed discussions of each of SiD's various subsystems, an overview of the full GEANT4 description of SiD, the status of newly developed tracking and calorimeter reconstruction algorithms, studies of subsystem performance based on these tools, results of physics benchmarking analyses, an estimate of the cost of the detector, and an assessment of the detector R&D needed to provide the technical basis for an optimised SiD.
Date:
May 26, 2010
Creator:
Aihara, H.; Burrows, P. & Oreglia, M.
Object Type:
Report
System:
The UNT Digital Library
Determination of the Optimal Number of Strata for Bias Reduction in Propensity Score Matching.
Previous research implementing stratification on the propensity score has generally relied on using five strata, based on prior theoretical groundwork and minimal empirical evidence as to the suitability of quintiles to adequately reduce bias in all cases and across all sample sizes. This study investigates bias reduction across varying number of strata and sample sizes via a large-scale simulation to determine the adequacy of quintiles for bias reduction under all conditions. Sample sizes ranged from 100 to 50,000 and strata from 3 to 20. Both the percentage of bias reduction and the standardized selection bias were examined. The results show that while the particular covariates in the simulation met certain criteria with five strata that greater bias reduction could be achieved by increasing the number of strata, especially with larger sample sizes. Simulation code written in R is included.
Date:
May 2010
Creator:
Akers, Allen
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Routine Leisure Activities and Adolescent Marijuana Use: Moderating Effects of Family Structure
How adolescents spend their time is a crucial predictor of their engagement in delinquency. Activities with peers away from direct supervision of adults are of concern as more opportunities and motivation to use marijuana exist in such situations. However, adolescents may vary in their propensity to use marijuana when faced the opportunity. Especially adolescents living with a single parent may have a higher propensity compared to those from two-parent households to use marijuana due to reduced parental monitoring and increased peer attachment. This thesis investigates the moderating effects of family structure on the routine leisure activities and adolescent marijuana use relationship, using data from Monitoring the Future Study 2007, 12th Grade Survey. The results provide partial support for the moderating effects.
Date:
May 2010
Creator:
Aksu, Gokhan
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
L'emploi variable des signes diacritiques dans le français tchaté : une étude variationniste en temps apparent .
After providing an historical overview of the French spelling system and orthographic variation, this study analyzes selected internal (i.e., linguistic) factors and one external (i.e., social) factor that can influence the use of diacritics in online French-language chat sessions. From a corpus of synchronous computer-mediated communication, 3,855 tokens of graphemes capable of bearing diacritics were coded with the following scheme: Letter, Diacritic, Grapheme (i.e., Letter and Diacritic combined), Date of Participation, and Age Group of Participant. A multivariate (VARBRUL) analysis determined that Grapheme exerts the most influence on variation.
Date:
May 2010
Creator:
Al-Rashdan, Omar
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Alternative Muon Front-end for the International Design Study (IDS)
We discuss alternative designs of the muon capture front end of the Neutrino Factory International Design Study (IDS). In the front end, a proton bunch on a target creates secondary pions that drift into a capture channel, decaying into muons. A sequence of RF cavities forms the resulting muon beams into strings of bunches of differing energies, aligns the bunches to (nearly) equal central energies, and initiates ionization cooling. This design is affected by limitations on accelerating gradients within magnetic fields. The effects of gradient limitations are explored, and mitigation strategies are presented.
Date:
May 1, 2010
Creator:
Alekou, A.; Neuffer, D.; Martini, M.; Prior, G.; Rogers, C.; Stratakis, D. et al.
Object Type:
Article
System:
The UNT Digital Library
Rapid-cycling synchrotron with variable momentum compaction
There are conflicting requirements on the value of the momentum compaction factor during energy ramping in a synchrotron: at low energies it should be positive and sufficiently large to make the slippage factor small so that it is possible to work closer to the RF voltage crest and ensure sufficient RF bucket area, whereas at higher energies it should be small or negative to avoid transition crossing. In the present report we propose a lattice with a variable momentum compaction factor and consider the possibility of using it in a high repetition rate proton driver for a muon collider and neutrino factory.
Date:
May 1, 2010
Creator:
Alexahin, Y. & Summers, D. J.
Object Type:
Article
System:
The UNT Digital Library
Muon collider interaction region design
Design of a muon collider interaction region (IR) presents a number of challenges arising from low {beta}* < 1 cm, correspondingly large beta-function values and beam sizes at IR magnets, as well as the necessity to protect superconducting magnets and collider detectors from muon decay products. As a consequence, the designs of the IR optics, magnets and machine-detector interface are strongly interlaced and iterative. A consistent solution for the 1.5 TeV c.o.m. muon collider IR is presented. It can provide an average luminosity of 10{sup 34} cm{sup -2}s{sup -1} with an adequate protection of magnet and detector components.
Date:
May 1, 2010
Creator:
Alexahin, Y. I.; Gianfelice-Wendt, E.; Kashikhin, V. V.; Mokhov, N. V.; Zlobin, A. V. & Alexakhin, V. Y.
Object Type:
Article
System:
The UNT Digital Library
Tune Evaluation From Phased BPM Turn-By-Turn Data
In fast ramping synchrotrons like the Fermilab Booster the conventional methods of betatron tune evaluation from the turn-by-turn data may not work due to rapid changes of the tunes (sometimes in a course of a few dozens of turns) and a high level of noise. We propose a technique based on phasing of signals from a large number of BPMs which significantly increases the signal to noise ratio. Implementation of the method in the Fermilab Booster control system is described and some measurement results are presented.
Date:
May 18, 2010
Creator:
Alexahin, Y.; Gianfelice-Wendt, E. & Marsh, W.
Object Type:
Article
System:
The UNT Digital Library
Conceptual design of the muon collider ring lattice
Muon collider is a promising candidate for the next energy frontier machine. However, in order to obtain peak luminosity in the 10{sup 35}/cm{sup 2}/s range the collider lattice design must satisfy a number of stringent requirements, such as low beta at IP ({beta}* < 1 cm), large momentum acceptance and dynamic aperture and small value of the momentum compaction factor. Here we present a particular solution for the interaction region optics whose distinctive feature is a three-sextupole local chromatic correction scheme. Together with a new flexible momentum compaction arc cell design this scheme allows to satisfy all the above-mentioned requirements and is relatively insensitive to the beam-beam effect.
Date:
May 1, 2010
Creator:
Alexahin, Y.; Gianfelice-Wendt, E.; Netepenko, A. & /Fermilab
Object Type:
Article
System:
The UNT Digital Library
Enhancing the US Power Infrastructure
The primary motivation for this set of research activities was to develop a foundation in several aspects of power in order to position Cleveland State University to lead a multiuniversity effort to secure funding for enhanced power system projects and to be able to eventually secure a NASA Space Power Systems Center status through the competitive bidding process. This was accomplished by focusing on these major project areas, (1) the design of the next generation nuclear-electric power generation system, (2) the design of a distributed, fault-tolerant, and modular power system, and (3) the development of the dynamics and control of active magnetic bearings for flywheel energy storage without using conventional sensors.
Date:
May 31, 2010
Creator:
Alexander, Charles
Object Type:
Report
System:
The UNT Digital Library
Electron Cloud at Low Emittance in CesrTA
The Cornell Electron Storage Ring (CESR) has been reconfigured as a test accelerator (CesrTA) for a program of electron cloud (EC) research at ultra low emittance. The instrumentation in the ring has been upgraded with local diagnostics for measurement of cloud density and with improved beam diagnostics for the characterization of both the low emittance performance and the beam dynamics of high intensity bunch trains interacting with the cloud. A range of EC mitigation methods have been deployed and tested and their effectiveness is discussed. Measurements of the electron cloud's effect on the beam under a range of conditions are discussed along with the simulations being used to quantitatively understand these results.
Date:
May 23, 2010
Creator:
Alexander, J. P.; Billing, M. G.; Calvey, J.; Crittenden, J. A.; Dugan, G.; Eggert, N. et al.
Object Type:
Article
System:
The UNT Digital Library
A Review of X-ray Diagnostic Calibrations in the 2 to 100 keV Region Using the High Energy X-ray Calibration Facility (HEX)
The precise and accurate measurement of X-rays in the 2 keV to 100 keV region is crucial to the understanding of HED plasmas and warm dense matter in general. With the emergence of inertially confined plasma facilities as the premier platforms for ICF, laboratory astrophysics, and national security related plasma experiments, the need to calibrate diagnostics in the high energy X-ray regime has grown. At National Security Technologies High Energy X-ray Calibration Facility (HEX) in Livermore, California, X-ray imagers, filter-fluorescer spectrometers, crystal spectrometers, image plates, and nuclear diagnostics are calibrated. The HEX can provide measurements of atomic line radiation, X-ray flux (accuracy within 10%), and X-ray energy (accuracy within 1%). The HEX source is comprised of a commercial 160 kV X-ray tube, a fluorescer wheel, a filter wheel, and a lead encasement. The X-ray tube produces a Tungsten bremsstrahlung spectrum which causes a foil to fluoresce line radiation. To minimize bremsstrahlung in the radiation for calibration we also provide various foils as filters. For experimental purposes, a vacuum box capable of 10{sup -7} Torr, as well as HPGe and CdTe radiation detectors, are provided on an optical table. Most geometries and arrangements can be changed to meet experimental needs.
Date:
May 19, 2010
Creator:
Ali, Zaheer; Pond, T.; Buckles, R. A.; Maddox, B. R.; Chen, C. D.; DeWald, E. L. et al.
Object Type:
Article
System:
The UNT Digital Library
U.S. Strategic Petroleum Reserve Vapor Pressure Committee 2009 annual report.
This report comprises an annual summary of activities under the U.S. Strategic Petroleum Reserve (SPR) Vapor Pressure Committee in FY2009. The committee provides guidance to senior project management on the issues of crude oil vapor pressure monitoring nd mitigation. The principal objectives of the vapor pressure program are, in the event of an SPR drawdown, to minimize the impact on the environment and assure worker safety and public health from crude oil vapor emissions. The annual report reviews key program areas ncluding monitoring program status, mitigation program status, new developments in measurements and modeling, and path forward including specific recommendations on cavern sampling for the next year. The contents of this report were first presented to SPR senior anagement in December 2009, in a deliverable from the vapor pressure committee. The current SAND report is an adaptation for the Sandia technical audience.
Date:
May 1, 2010
Creator:
Allen, Ray (Allen Energy Services, Inc., Longview, TX); Eldredge, Lisa (DynMcDermott Petroleum Operations, Harahan, LA); DeLuca, Charles (DynMcDermott Petroleum Operations, Harahan, LA); Mihalik, Patrick (DynMcDermott Petroleum Operations, Harahan, LA); Maldonado, Julio (U.S. Department of Energy, Harahan, LA); Lord, David L. et al.
Object Type:
Report
System:
The UNT Digital Library
Effects of Suspended Multi-Walled Carbon Nanotubes on Daphnid Growth and Reproduction
Multi-walled carbon nanotube aggregates can be suspended in the aqueous phase by natural organic matter. These aggregates are ingested by filter feeding zooplankton. Ingested aggregates result in decreased growth and decreased reproduction. These effects may be caused by reduction in energy input from normal feeding behavior. pH alters natural organic matter structure through changes in electrostatic repulsion. Altered natural organic matter structure changes multi-walled carbon nanotube aggregate size. This size variation with variation in pH is significant, but not large enough a change in size to alter toxicity, as the aggregate size range remains well within the particle size selection of the organisms.
Date:
May 2010
Creator:
Alloy, Matthew Michael
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library