Z' Coupling Information From LHeC (open access)

Z' Coupling Information From LHeC

None
Date: April 4, 2008
Creator: Rizzo, Thomas G.
Object Type: Article
System: The UNT Digital Library
Resonant Soft X-Ray Contrast Variation Methods as Composition-Specific Probes of Thin Polymer Film Structure (open access)

Resonant Soft X-Ray Contrast Variation Methods as Composition-Specific Probes of Thin Polymer Film Structure

We have developed complementary soft x-ray scattering and reflectometry techniques that allow for the morphological analysis of thin polymer films without resorting to chemical modification or isotopic 2 labeling. With these techniques, we achieve significant, x-ray energy-dependent contrast between carbon atoms in different chemical environments using soft x-ray resonance at the carbon edge. Because carbon-containing samples absorb strongly in this region, the scattering length density depends on both the real and imaginary parts of the atomic scattering factors. Using a model polymer film of poly(styrene-b-methyl methacrylate), we show that the soft x-ray reflectivity data is much more sensitive to these atomic scattering factors than the soft x-ray scattering data. Nevertheless, fits to both types of data yield useful morphological details on the polymer?slamellar structure that are consistent with each other and with literature values.
Date: April 4, 2008
Creator: Welch, Cynthia; Welch, Cynthia F.; Hjelm, Rex P.; Mang, Joseph T.; Hawley, Marilyn E.; Wrobleski, Debra A. et al.
Object Type: Article
System: The UNT Digital Library
Breaking the Curse of Cardinality on Bitmap Indexes (open access)

Breaking the Curse of Cardinality on Bitmap Indexes

Bitmap indexes are known to be efficient for ad-hoc range queries that are common in data warehousing and scientific applications. However, they suffer from the curse of cardinality, that is, their efficiency deteriorates as attribute cardinalities increase. A number of strategies have been proposed, but none of them addresses the problem adequately. In this paper, we propose a novel binned bitmap index that greatly reduces the cost to answer queries, and therefore breaks the curse of cardinality. The key idea is to augment the binned index with an Order-preserving Bin-based Clustering (OrBiC) structure. This data structure significantly reduces the I/O operations needed to resolve records that cannot be resolved with the bitmaps. To further improve the proposed index structure, we also present a strategy to create single-valued bins for frequent values. This strategy reduces index sizes and improves query processing speed. Overall, the binned indexes with OrBiC great improves the query processing speed, and are 3 - 25 times faster than the best available indexes for high-cardinality data.
Date: April 4, 2008
Creator: Wu, Kesheng; Wu, Kesheng; Stockinger, Kurt & Shoshani, Arie
Object Type: Article
System: The UNT Digital Library
On a Thermal Analysis of a Second Stripper for Rare Isotope Accelerator. (open access)

On a Thermal Analysis of a Second Stripper for Rare Isotope Accelerator.

This memo summarizes simple calculations and results of the thermal analysis on the second stripper to be used in the driver linac of Rare Isotope Accelerator (RIA). Both liquid (Sodium) and solid (Titanium and Vanadium) stripper concepts were considered. These calculations were intended to provide basic information to evaluate the feasibility of liquid (thick film) and solid (rotating wheel) second strippers. Nuclear physics calculations to estimate the volumetric heat generation in the stripper material were performed by 'LISE for Excel'. In the thermal calculations, the strippers were modeled as a thin 2D plate with uniform heat generation within the beam spot. Then, temperature distributions were computed by assuming that the heat spreads conductively in the plate in radial direction without radiative heat losses to surroundings.
Date: August 4, 2008
Creator: Momozaki, Y. & Nolen, J.
Object Type: Report
System: The UNT Digital Library
Measurement of D^0-\bar{D^0} Mixing From a Time-Dependent Amplitude Analysis of D^0\ -> K^+\pi^-\pi0 Decays (open access)

Measurement of D^0-\bar{D^0} Mixing From a Time-Dependent Amplitude Analysis of D^0\ -> K^+\pi^-\pi0 Decays

The authors present evidence of D{sup 0}-{bar D}{sup 0} mixing using a time-dependent amplitude analysis of the decay D{sup 0} {yields} K{sup +}{pi}{sup -}{pi}{sup 0} in a data sample of 384 fb{sup -1} collected with the BABAR detector at the PEP-II e{sup +}e{sup -} collider at SLAC. Assuming CP conservation, they measure the mixing parameters x{prime}{sub K{pi}{pi}{sup 0}} = [2.61{sub -0.68}{sup +0.57}(stat.) {+-} 0.39(syst.)]%, y{prime}{sub K{pi}{pi}{sup 0}} = [-0.06{sub -0.64}{sup +0.55}(stat.) {+-} 0.34(syst.)]%. The confidence level for the data to be consistent with the no-mixing hypothesis is 0.1%, including systematic uncertainties. This result is inconsistent with the no-mixing hypothesis with a significance of 3.2 standard deviations. They find no evidence of CP violation in mixing.
Date: August 4, 2008
Creator: Aubert, Bernard; Bona, M.; Karyotakis, Y.; Lees, J. P.; Poireau, V.; Prencipe, E. et al.
Object Type: Article
System: The UNT Digital Library
INVESTIGATION OF THE PRESENCE OF DRUGSTORE BEETLES WITHIN CELOTEX ASSEMBLIES IN RADIOACTIVE MATERIAL PACKAGINGS (open access)

INVESTIGATION OF THE PRESENCE OF DRUGSTORE BEETLES WITHIN CELOTEX ASSEMBLIES IN RADIOACTIVE MATERIAL PACKAGINGS

During normal operations at the Department of Energy's Hanford Site in Hanford, WA, drugstore beetles, (Stegobium paniceum (L.) Coleoptera: Anobiidae), were found within the fiberboard subassemblies of two 9975 Shipping Packages. Initial indications were that the beetles were feeding on the Celotex{trademark} assemblies within the package. Celotex{trademark} fiberboard is used in numerous radioactive material packages serving as both a thermal insulator and an impact absorber for both normal conditions of transport and hypothetical accident conditions. The Department of Energy's Packaging Certification Program (EM-63) directed a thorough investigation to determine if the drugstore beetles were causing damage that would be detrimental to the safety performance of the Celotex{trademark}. The Savannah River National Laboratory is conducting the investigation with entomological expertise provided by Clemson University. The two empty 9975 shipping packages were transferred to the Savannah River National Laboratory in the fall of 2007. This paper will provide details and results of the ongoing investigation.
Date: June 4, 2008
Creator: Loftin, B & Glenn Abramczyk, G
Object Type: Article
System: The UNT Digital Library
Ferromagnetism in GaN: Gd: A density functional theory study (open access)

Ferromagnetism in GaN: Gd: A density functional theory study

First principle calculations of the electronic structure and magnetic interaction of GaN:Gd have been performed within the Generalized Gradient Approximation (GGA) of the density functional theory (DFT) with the on-site Coulomb energy U taken into account (also referred to as GGA+U). The ferromagnetic p-d coupling is found to be over two orders of magnitude larger than the s-d exchange coupling. The experimental colossal magnetic moments and room temperature ferromagnetism in GaN:Gd reported recently are explained by the interaction of Gd 4f spins via p-d coupling involving holes introduced by intrinsic defects such as Ga vacancies.
Date: February 4, 2008
Creator: Stevenson, Cynthia & Stevenson, Cynthia
Object Type: Article
System: The UNT Digital Library
Measurements of {\cal B}(\overline{B}^0 \to \Lambda_{c}^{+} \overline{p}) and {\cal B}(B^- \to \Lambda_{c}^{+} \overline{p} \pi^-) and Studies of \Lambda_{c}^{+}\pi^- Resonances (open access)

Measurements of {\cal B}(\overline{B}^0 \to \Lambda_{c}^{+} \overline{p}) and {\cal B}(B^- \to \Lambda_{c}^{+} \overline{p} \pi^-) and Studies of \Lambda_{c}^{+}\pi^- Resonances

The authors present an investigation of the decays {bar B}{sup 0} {yields} {Lambda}{sub c}{sup +}{bar p} and B{sup -} {yields} {Lambda}{sub c}{sup +}{bar p}{pi}{sup -} based on 383 x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} decays recorded with the BABAR detector. They measure the branching fractions of these decays; their ratio is {Beta}(B{sup -} {yields} {Lambda}{sub c}{sup +}{bar p}{pi}{sup -})/{Beta}({bar B}{sup 0} {yields} {Lambda}{sub c}{sup +}{bar p}) = 15.4 {+-} 1.8 {+-} 0.3. The B{sup -} {yields} {Lambda}{sub c}{sup +}{bar p}{pi}{sup -} process exhibits an enhancement at the {Lambda}{sub c}{sup +}{bar p} threshold and is a laboratory for searches for excited charm baryon states. They observe the resonant decays B{sup -} {yields} {Sigma}{sub c}(2455){sup 0}{bar p} and B{sup -} {Sigma}{sub c}(2800){sup 0}{bar p} but see no evidence for B{sup -} {yields} {Sigma}{sub c}(2520){sup 0}{bar p}. This is the first observation of the decay B{sup -} {yields} {Sigma}{sub c}(2800){sup 0}{bar p}; however, the mass of the observed excited {Sigma}{sub c}{sup 0} state is (2846 {+-} 8 {+-} 10) MeV/c{sup 2}, which is somewhat inconsistent with previous measurements. Finally, they examine the angular distribution of the B{sup -} {yields} {Sigma}{sub c}(2455){sup 0}{bar p} decays and measure the spin of the {Sigma}{sub c}(2455){sup …
Date: August 4, 2008
Creator: Collaboration, The BABAR & Aubert, B.
Object Type: Article
System: The UNT Digital Library
Improving Ventilation and Saving Energy: Final Report on Indoor Environmental Quality and Energy Monitoring in Sixteen Relocatable Classrooms (open access)

Improving Ventilation and Saving Energy: Final Report on Indoor Environmental Quality and Energy Monitoring in Sixteen Relocatable Classrooms

An improved HVAC system for portable classrooms was specified to address key problems in existing units. These included low energy efficiency, poor control of and provision for adequate ventilation, and excessive acoustic noise. Working with industry, a prototype improved heat pump air conditioner was developed to meet the specification. A one-year measurement-intensive field-test of ten of these IHPAC systems was conducted in occupied classrooms in two distinct California climates. These measurements are compared to those made in parallel in side by side portable classrooms equipped with standard 10 SEER heat pump air conditioner equipment. The IHPAC units were found to work as designed, providing predicted annual energy efficiency improvements of about 36 percent to 42 percent across California's climate zones, relative to 10 SEER units. Classroom ventilation was vastly improved as evidenced by far lower indoor minus outdoor CO2 concentrations. TheIHPAC units were found to provide ventilation that meets both California State energy and occupational codes and the ASHRAE minimum ventilation requirements; the classrooms equipped with the 10 SEER equipment universally did not meet these targets. The IHPAC system provided a major improvement in indoor acoustic conditions. HVAC system generated background noise was reduced in fan-only and fan and compressor …
Date: April 4, 2008
Creator: Apte, Michael G.; Norman, Bourassa; Faulkner, David; Hodgson, Alfred T.; Hotchi, Toshfumi; Spears, Michael et al.
Object Type: Report
System: The UNT Digital Library
FINAL FRONTIER AT HANFORD TACKLING THE CENTRAL PLATEAU (open access)

FINAL FRONTIER AT HANFORD TACKLING THE CENTRAL PLATEAU

The large land area in the center of the vast Department of Energy (DOE) Hanford Site in southeast Washington State is known as 'the plateau'--aptly named because its surface elevations are 250-300 feet above the groundwater table. By contrast, areas on the 585-square mile Site that border the Columbia River sit just 30-80 feet above the water table. The Central Plateau, which covers an ellipse of approximately 70 square miles, contains Hanford's radiochemical reprocessing areas--the 200 East and 200 West Areas--and includes the most highly radioactive waste and contaminated facilities on the Site. Five 'canyons' where chemical processes were used to separate out plutonium (Pu), 884 identified soil waste sites (including approximately 50 miles of solid waste burial trenches), more than 900 structures, and all of Hanford's liquid waste storage tanks reside in the Central Plateau. (Notes: Canyons is a nickname given by Hanford workers to the chemical reprocessing facilities. The 177, underground waste tanks at Hanford comprise a separate work scope and are not under Fluor's management). Fluor Hanford, a DOE prime cleanup contractor at the Site for the past 12 years, has moved aggressively to investigate Central Plateau waste sites in the last few years, digging more than …
Date: March 4, 2008
Creator: MS, GERBER
Object Type: Article
System: The UNT Digital Library
Time-Dependent and Time-Integrated Angular Analysis of B -> phi Ks pi0 and B -> phi K+ pi- (open access)

Time-Dependent and Time-Integrated Angular Analysis of B -> phi Ks pi0 and B -> phi K+ pi-

We perform a time-dependent and time-integrated angular analysis of the B{sup 0} {yields} {psi}K*(892){sup 0}, {psi}K*{sub 2}(1430{sup 0}), and {psi}(K{pi}){sub S-wave}{sup 0} decays with the final sample of about 465 million B{bar B} pairs recorded with the BABAR detector. Overall, twelve parameters are measured for the vector-vector decay, nine parameters for the vector-tensor decay, and three parameters for the vector-scalar decay, including the branching fractions, CP-violation parameters, and parameters sensitive to final state interaction. We use the dependence on the K{pi} invariant mass of the interference between the scalar and vector or tensor components to resolve discrete ambiguities of the strong and weak phases. We use the time-evolution of the B {yields} {psi}K{sub S}{sup 0}{pi}{sup 0} channel to extract the CP-violation phase difference {Delta}{phi}{sub 00} = 0.28 {+-} 0.42 {+-} 0.04 between the B and {bar B} decay amplitudes. When the B {yields} {psi}K{sup {+-}}{pi}{sup {-+}} channel is included, the fractions of longitudinal polarization f{sub L} of the vector-vector and vector-tensor decay modes are measured to be 0.494 {+-} 0.034 {+-} 0.013 and 0.901{sub -0.058}{sup +0.046} {+-} 0.037, respectively. This polarization pattern requires the presence of a helicity-plus amplitude in the vector-vector decay from a presently unknown source.
Date: August 4, 2008
Creator: Aubert, B.; Bona, M.; Karyotakis, Y; Lees, J.P. & Poireau, V.
Object Type: Article
System: The UNT Digital Library
Measuring Regional Changes in the Diastolic Deformation of the Left Ventricle of SHR Rats Using microPET Technology and Hyperelastic Warping (open access)

Measuring Regional Changes in the Diastolic Deformation of the Left Ventricle of SHR Rats Using microPET Technology and Hyperelastic Warping

The objective of this research was to assess applicability of a technique known as hyperelastic warping for the measurement of local strains in the left ventricle (LV) directly from microPET image data sets. The technique uses differences in image intensities between template (reference) and target (loaded) image data sets to generate a body force that deforms a finite element (FE) representation of the template so that it registers with the target images. For validation, the template image was defined as the end-systolic microPET image data set from a Wistar Kyoto (WKY) rat. The target image was created by mapping the template image using the deformation results obtained from a FE model of diastolic filling. Regression analysis revealed highly significant correlations between the simulated forward FE solution and image derived warping predictions for fiber stretch (R2 = 0.96), circumferential strain (R2 = 0.96), radial strain (R2 = 0.93), and longitudinal strain (R2 = 0.76) (p<0.001for all cases). The technology was applied to microPET image data of two spontaneously hypertensive rats (SHR) and a WKY control. Regional analysis revealed that, the lateral freewall in the SHR subjects showed the greatest deformation compared with the other wall segments. This work indicates that warping …
Date: April 4, 2008
Creator: Gullberg, Grant T; Veress , Alexander I.; Weiss, Jeffrey A.; Huesman, Ronald H.; Reutter, Bryan W.; Taylor , Scott E. et al.
Object Type: Article
System: The UNT Digital Library
Direct Observation of the Kinetically Relevant Site of CO Hydrogenation on Supported Ru Catalyst at 700 K by Time-Resolved FT-IR Spectroscopy (open access)

Direct Observation of the Kinetically Relevant Site of CO Hydrogenation on Supported Ru Catalyst at 700 K by Time-Resolved FT-IR Spectroscopy

Time-resolved FT-IR spectra of carbon monoxide hydrogenation over alumina-supported ruthenium particles were recorded on themillisecond time scale at 700 K using pulsed release of CO and a continuous flow of H2/N2 (ratio 0.067 or 0.15, 1 atm total pressure). Adsorbed carbon monoxide was detected along with gas phase products methane (3016 and 1306 cm-1), water (1900 +- 1300 cm-1), and carbon dioxide (2348 cm-1). Aside from adsorbed CO, no other surface species were observed. The rate of formation of methane is 2.5 +- 0.4 s-1 and coincides with the rate of carbon dioxide growth (3.4 +- 0.6 s-1), thus indicating that CH4 and CO2 originate from a common intermediate. The broad band of adsorbed carbon monoxide has a maximum at 2010 cm-1 at early times (36 ms) that shifts gradually to 1960 cm-1 over a period of 3 s as a result of the decreasing surface concentration of CO. Kinetic analysis of the adsorbed carbon monoxide reveals that surface sites absorbing at the high frequency end of the infrared band are temporally linked to gas phase product growth. Specifically, a (linear) CO site at 2026 cm-1 decays with a rate constant of 2.9 +- 0.1 s-1, which coincides with the …
Date: June 4, 2008
Creator: Frei, Heinz; Wasylenko, Walter & Frei, Heinz
Object Type: Article
System: The UNT Digital Library
Pyrrole Hydrogenation over Rh(111) and Pt(111) Single-Crystal Surfaces and Hydrogenation Promotion Mediated by 1-Methylpyrrole: A Kinetic and Sum-Frequency Generation Vibrational Spectroscopy Study (open access)

Pyrrole Hydrogenation over Rh(111) and Pt(111) Single-Crystal Surfaces and Hydrogenation Promotion Mediated by 1-Methylpyrrole: A Kinetic and Sum-Frequency Generation Vibrational Spectroscopy Study

Sum-frequency generation (SFG) surface vibrational spectroscopy and kinetic measurements using gas chromatography have been used to study the adsorption and hydrogenation of pyrrole over both Pt(111) and Rh(111) single-crystal surfaces at Torr pressures (3 Torr pyrrole, 30 Torr H{sub 2}) to form pyrrolidine and the minor product butylamine. Over Pt(111) at 298 K it was found that pyrrole adsorbs in an upright geometry cleaving the N-H bond to bind through the nitrogen evidenced by SFG data. Over Rh(111) at 298 K pyrrole adsorbs in a tilted geometry relative to the surface through the p-aromatic system. A pyrroline surface reaction intermediate, which was not detected in the gas phase, was seen by SFG during the hydrogenation over both surfaces. Significant enhancement of the reaction rate was achieved over both metal surfaces by adsorbing 1-methylpyrrole before reaction. SFG vibrational spectroscopic results indicate that reaction promotion is achieved by weakening the bonding between the N-containing products and the metal surface because of lateral interactions on the surface between 1-methylpyrrole and the reaction species, reducing the desorption energy of the products. It was found that the ring-opening product butylamine was a reaction poison over both surfaces, but this effect can be minimized by treating …
Date: March 4, 2008
Creator: Kliewer, Christopher J.; Bieri, Marco & Somorjai, Gabor A.
Object Type: Article
System: The UNT Digital Library
Integrated Optical Probes (open access)

Integrated Optical Probes

Optical probes used in velocimetry measurements have typically been individual probes that collect data for a single diagnostic at a single point. These probes have been used in diagnostics such as VISAR, PDV, and radiometry, which measure surface velocity, temperature, and other characteristics. When separate probes are used for these measurements, the different diagnostic points measured must be significantly separated. We have developed integrated probes that collect data for multiple optical diagnostics; these probes measure points in close proximity.
Date: September 4, 2008
Creator: Brent Frogget, Douglas DeVore, Vincent Romero, David Esquibel, and David Holtkamp
Object Type: Article
System: The UNT Digital Library
Miscellaneous: Uruguay Energy Supply Options Study Assessing the Market for Natural Gas - Executive Summary. (open access)

Miscellaneous: Uruguay Energy Supply Options Study Assessing the Market for Natural Gas - Executive Summary.

Uruguay is in the midst of making critical decisions affecting the design of its future energy supply system. Momentum for change is expected to come from several directions, including recent and foreseeable upgrades and modifications to energy conversion facilities, the importation of natural gas from Argentina, the possibility for a stronger interconnection of regional electricity systems, the country's membership in MERCOSUR, and the potential for energy sector reforms by the Government of Uruguay. The objective of this study is to analyze the effects of several fuel diversification strategies on Uruguay's energy supply system. The analysis pays special attention to fuel substitution trends due to potential imports of natural gas via a gas pipeline from Argentina and increasing electricity ties with neighboring countries. The Government of Uruguay has contracted with Argonne National Laboratory (ANL) to study several energy development scenarios with the support of several Uruguayan institutions. Specifically, ANL was asked to conduct a detailed energy supply and demand analysis, develop energy demand projections based on an analysis of past energy demand patterns with support from local institutions, evaluate the effects of potential natural gas imports and electricity exchanges, and determine the market penetration of natural gas under various scenarios.
Date: March 4, 2008
Creator: Conzelmann, G.; Veselka, T. & Sciences, Decision and Information
Object Type: Report
System: The UNT Digital Library
April 2008 Monitoring Report for Morrill, Kansas. (open access)

April 2008 Monitoring Report for Morrill, Kansas.

In September 2005, the Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) initiated periodic sampling of groundwater in the vicinity of a grain storage facility formerly operated by the CCC/USDA at Morrill, Kansas. The sampling at Morrill is being performed on behalf of the CCC/USDA by Argonne National Laboratory, in accord with a monitoring program approved by the Kansas Department of Health and Environment (KDHE), to monitor levels of carbon tetrachloride contamination identified in the groundwater at this site (Argonne 2004, 2005a). This report provides results for the most recent monitoring event, in April 2008. Under the KDHE-approved monitoring plan (Argonne 2005b), groundwater was initially sampled twice yearly for a recommended period of two years (in fall 2005, in spring and fall 2006, and in spring and fall 2007). The samples were analyzed for volatile organic compounds (VOCs), as well as for selected geochemical parameters to aid in the evaluation of possible natural contaminant degradation (reductive dechlorination) processes in the subsurface environment. During the recommended two-year period, the originally approved scope of the monitoring was expanded to include vegetation sampling (initiated in October 2006) and surface water and stream bed sediment sampling (initiated in March 2007, after a …
Date: November 4, 2008
Creator: LaFreniere, L. M.
Object Type: Report
System: The UNT Digital Library
Status of the Fast Focusing DIRC (fDIRC) (open access)

Status of the Fast Focusing DIRC (fDIRC)

We have built and successfully tested a novel particle identification detector concept, the Fast Focusing DIRC (fDIRC). The prototype's concept is based on the BaBar DIRC with several important improvements: (a) much faster pixelated photon detectors based on Burle MCP-PMTs and Hamamatsu MaPMTs, (b) a focusing mirror allowing a smaller photon detector, reducing the sensitivity to backgrounds in future applications, (c) electronics capable of measuring the single photon resolution to better than {sigma} {approx} 100-200ps. The fDIRC is the first RICH detector to successfully correct the chromatic error by timing.
Date: February 4, 2008
Creator: Benitez, J.; Leith, D. W. G. S.; Mazaheri, G.; Ratcliff, B. N.; Schwiening, J.; Vavra, J. et al.
Object Type: Article
System: The UNT Digital Library
CO2 Separation Using Thermally Optimized Membranes: A Comprehensive Project Report (2000 - 2007) (open access)

CO2 Separation Using Thermally Optimized Membranes: A Comprehensive Project Report (2000 - 2007)

This is a complete (Fiscal Years 2000–2006) collection of the Idaho National Laboratory’s (INL) research and development contributions to the project, “CO2 Separation Using Thermally Optimized Membranes.” The INL scientific contribution to the project has varied due to the fluctuations in funding from year to year. The focus of the project was polybenzimidazole (PBI) membranes and developing PBI compounds (both substitution and blends) that provide good film formation and gas separation membranes. The underlying problem with PBI is its poor solubility in common solvents. Typically, PBI is dissolved in “aggressive” solvents, like N,N-dimethylacetamide (DMAc) and N methylpyrrolidone (NMP). The INL FY-03 research was directed toward making soluble N-substituted PBI polymers, where INL was very successful. Many different types of modified PBI polymers were synthesized; however, film formation proved to be a big problem with both unsubstituted and N-substituted PBIs. Therefore, INL researchers directed their attention to using plasticizers or additives to make the membranes more stable and workable. During the course of these studies, other high-performance polymers (like polyamides and polyimides) were found to be better materials, which could be used either by themselves or blends with PBI. These alternative high-performance polymers provided the best pathway forward for soluble high-temperature …
Date: March 4, 2008
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Ultrafast high strain rate acoustic wave measurements at high static pressure in a diamond anvil cell (open access)

Ultrafast high strain rate acoustic wave measurements at high static pressure in a diamond anvil cell

We have used sub-picosecond laser pulses to launch ultra-high strain rate ({approx} 10{sup 9} s{sup -1}) nonlinear acoustic waves into a 4:1 methanol-ethanol pressure medium which has been precompressed in a standard diamond anvil cell. Using ultrafast interferometry, we have characterized acoustic wave propagation into the pressure medium at static compression up to 24 GPa. We find that the velocity is dependent on the incident laser fluence, demonstrating a nonlinear acoustic response which may result in shock wave behavior. We compare our results with low strain, low strain-rate acoustic data. This technique provides controlled access to regions of thermodynamic phase space that are otherwise difficult to obtain.
Date: February 4, 2008
Creator: Armstrong, M; Crowhurst, J; Reed, E & Zaug, J
Object Type: Article
System: The UNT Digital Library
Parallel 3D Finite Element Numerical Modelling of DC Electron Guns (open access)

Parallel 3D Finite Element Numerical Modelling of DC Electron Guns

In this paper we present Gun3P, a parallel 3D finite element application that the Advanced Computations Department at the Stanford Linear Accelerator Center is developing for the analysis of beam formation in DC guns and beam transport in klystrons. Gun3P is targeted specially to complex geometries that cannot be described by 2D models and cannot be easily handled by finite difference discretizations. Its parallel capability allows simulations with more accuracy and less processing time than packages currently available. We present simulation results for the L-band Sheet Beam Klystron DC gun, in which case Gun3P is able to reduce simulation time from days to some hours.
Date: February 4, 2008
Creator: Prudencio, E.; Candel, A.; Ge, L.; Kabel, A.; Ko, K.; Lee, L. et al.
Object Type: Report
System: The UNT Digital Library
AdS/CFT and Light-Front QCD (open access)

AdS/CFT and Light-Front QCD

The AdS/CFT correspondence between string theory in AdS space and conformal field theories in physical space-time leads to an analytic, semi-classical model for strongly-coupled QCD which has scale invariance and dimensional counting at short distances and color confinement at large distances. The AdS/CFT correspondence also provides insights into the inherently nonperturbative aspects of QCD such as the orbital and radial spectra of hadrons and the form of hadronic wavefunctions. In particular, we show that there is an exact correspondence between the fifth-dimensional coordinate of AdS space z and a specific impact variable {zeta} which measures the separation of the quark and gluonic constituents within the hadron in ordinary space-time. This connection leads to AdS/CFT predictions for the analytic form of the frame-independent light-front wavefunctions (LFWFs) of mesons and baryons, the fundamental entities which encode hadron properties. The LFWFs in turn predict decay constants and spin correlations, as well as dynamical quantities such as form factors, structure functions, generalized parton distributions, and exclusive scattering amplitudes. Relativistic light-front equations in ordinary space-time are found which reproduce the results obtained using the fifth-dimensional theory and have remarkable algebraic structures and integrability properties. As specific examples we describe the behavior of the pion form …
Date: February 4, 2008
Creator: Brodsky, Stanley J. & de Teramond, Guy F.
Object Type: Article
System: The UNT Digital Library
Prototype performance of novel muon telescope detector at STAR (open access)

Prototype performance of novel muon telescope detector at STAR

Research on a large-area, cost-effective Muon Telescope Detector has been carried out for RHIC and for next generation detectors at future QCD Lab. We utilize state-of-the-art multi-gap resistive plate chambers with large modules and long readout strips in detector design [l]. The results from cosmic ray and beam test will be presented to address intrinsic timing and spatial resolution for a Long-MRF'C. The prototype performance of a novel muon telescope detector at STAR will be reported, including muon identification capability, timing and spatial resolution.
Date: February 4, 2008
Creator: Ruan,L. & Ames, V.
Object Type: Article
System: The UNT Digital Library
Song of the Electroweak Penguin (open access)

Song of the Electroweak Penguin

None
Date: April 4, 2008
Creator: Peskin, Michael E.
Object Type: Article
System: The UNT Digital Library