Estimating Filtering Errors Using the Peano Kernel Theorem (open access)

Estimating Filtering Errors Using the Peano Kernel Theorem

The Peano Kernel Theorem is introduced and a frequency domain derivation is given. It is demonstrated that the application of this theorem yields simple and accurate formulas for estimating the error introduced into a signal by filtering it to reduce noise.
Date: February 20, 2009
Creator: Blair, Jerome
Object Type: Article
System: The UNT Digital Library
Two-photon double ionization of H2 at 30 eV using Exterior Complex Scaling (open access)

Two-photon double ionization of H2 at 30 eV using Exterior Complex Scaling

Calculations of fully differential cross sections for two-photon double ionization of the hydrogen molecule with photons of 30 eV are reported. The results have been obtained by using the method of exterior complex scaling, which allows one to construct essentially exact wave functions that describe thedouble continuum on a large, but finite, volume. The calculated cross sections are compared with those previously obtained by Colgan et al., and discrepancies are found for specific molecular orientations and electron ejection directions.
Date: January 20, 2009
Creator: Morales, Felipe; Martin, Fernando; Horner, Daniel; Rescigno, Thomas N. & McCurdy, C. William
Object Type: Article
System: The UNT Digital Library
Analysis of Metabolic Pathways and Fluxes in a Newly Discovered Thermophilic and Ethanol-Tolerant Geobacillus Strain (open access)

Analysis of Metabolic Pathways and Fluxes in a Newly Discovered Thermophilic and Ethanol-Tolerant Geobacillus Strain

A recently discovered thermophilic bacterium, Geobacillus thermoglucosidasius M10EXG, ferments a range of C5 (e.g., xylose) and C6 sugars (e.g., glucose) and istolerant to high ethanol concentrations (10percent, v/v). We have investigated the central metabolism of this bacterium using both in vitro enzyme assays and 13C-based flux analysis to provide insights into the physiological properties of this extremophile and explore its metabolism for bio-ethanol or other bioprocess applications. Our findings show that glucose metabolism in G. thermoglucosidasius M10EXG proceeds via glycolysis, the pentose phosphate pathway, and the TCA cycle; the Entner?Doudoroff pathway and transhydrogenase activity were not detected. Anaplerotic reactions (including the glyoxylate shunt, pyruvate carboxylase, and phosphoenolpyruvate carboxykinase) were active, but fluxes through those pathways could not be accuratelydetermined using amino acid labeling. When growth conditions were switched from aerobic to micro-aerobic conditions, fluxes (based on a normalized glucose uptake rate of 100 units (g DCW)-1 h-1) through the TCA cycle and oxidative pentose phosphate pathway were reduced from 64+-3 to 25+-2 and from 30+-2 to 19+-2, respectively. The carbon flux under micro-aerobic growth was directed formate. Under fully anerobic conditions, G. thermoglucosidasius M10EXG used a mixed acid fermentation process and exhibited a maximum ethanol yield of 0.38+-0.07 mol mol-1 …
Date: January 20, 2009
Creator: Tang, Yinjie J.; Sapra, Rajat; Joyner, Dominique; Hazen, Terry C.; Myers, Samuel; Reichmuth, David et al.
Object Type: Article
System: The UNT Digital Library
Improving Consistency of Performance Assessments in the Doe Complex (open access)

Improving Consistency of Performance Assessments in the Doe Complex

The low-level waste (LLW) performance assessment (PA) process has been traditionally focused on disposal facilities at a few United States Department of Energy (USDOE) sites and commercial disposal facilities. In recent years, there has been a dramatic increase in the scope of the use of PA-like modeling approaches, involving multiple activities, facilities, contractors and regulators. The scope now includes, for example: (1) National Environmental Policy Act (NEPA) assessments, (2) CERCLA disposal cells, (3) Waste Determinations and High-Level Waste (HLW) Closure activities, (4) Potential on-site disposal of Transuranic (TRU) waste, and (5) In-situ decommissioning (including potential use of existing facilities for disposal). The dramatic increase in the variety of activities requiring more detailed modeling has resulted in a similar increase in the potential for inconsistency in approaches both at a site and complexwide scale. This paper includes a summary of USDOE Environmental Management (EM) sponsored initiatives and activities for improved consistency. New initiatives entitled the Performance Assessment Community of Practice and Performance Assessment Assistance Team are also introduced.
Date: January 20, 2009
Creator: Seitz, R. & Elmer Wilhite, E.
Object Type: Article
System: The UNT Digital Library
Final report SBIR Phase II. High current density,(Jc), low AC loss, low cost, Internal-Tin Superconductor (open access)

Final report SBIR Phase II. High current density,(Jc), low AC loss, low cost, Internal-Tin Superconductor

Final report of SBIR to develop an economical process that can produce the best material for high field magnets to be used in the next generation of accelerators
Date: January 20, 2009
Creator: Gregory, Eric
Object Type: Report
System: The UNT Digital Library
DOE Award No. DE-FC36-03GO13108 Novel Non-Precious Metal Catalysts for PEMFC: Catalyst Selection Through Molecular Modeling and Durability Studies Final Report (September 2003 – October 2008) (open access)

DOE Award No. DE-FC36-03GO13108 Novel Non-Precious Metal Catalysts for PEMFC: Catalyst Selection Through Molecular Modeling and Durability Studies Final Report (September 2003 – October 2008)

The objective of this project is to develop novel non-precious metal electrocatalysts for oxygen reduction reaction (ORR), and demonstrate the potential of the catalysts to perform at least as good as conventional Pt catalysts currently in use in polymer electrolyte membrane fuel cell (PEMFC) with a cost at least 50 % less than a target of 0.2 g (Pt loading)/peak kW and with durability > 2,000 h operation with less than 10 % power degradation. A novel nitrogen-modified carbon-based catalyst was obtained by modifying carbon black with nitrogen-containing organic precursor in the absence of transition metal precursor. The catalyst shows the onset potential of approximately 0.76 V (NHE) for ORR and the amount of H2O2 of approximately 3% at 0.5 V (NHE). Furthermore, a carbon composite catalyst was achieved through the high-temperature pyrolysis of the precursors of transition metal (Co and Fe) and nitrogen supported on the nitrogen-modified carbon-based catalyst, followed by chemical post-treatment. This catalyst showed an onset potential for ORR as high as 0.87 V (NHE), and generated less than 1 % of H2O2. The PEM fuel cell exhibited a current density of 2.3 A cm-2 at 0.2 V for a catalyst loading of 6.0 mg cm-2. No …
Date: February 20, 2009
Creator: Popov, Branko N.
Object Type: Report
System: The UNT Digital Library
Stochastic Boundary, Diffusion, Emittance Growth and Lifetime calculation for the RHIC e-lens (open access)

Stochastic Boundary, Diffusion, Emittance Growth and Lifetime calculation for the RHIC e-lens

To compensate the large tune shift and tune spread generated by the head-on beam-beam interactions in polarized proton operation in the Relativistic Heavy Ion Collider (RHIC), a low energy electron beam with proper Gaussian transverse profiles was proposed to collide head-on with the proton beam. In this article, using a modified version of SixTrack [1], we investigate stability of the single particle in the presence of head-on beam-beam compensation. The Lyapunov exponent and action diffusion are calculated and compared between the cases without and with beam-beam compensation for two different working points and various bunch intensities. Using the action diffusion results the emittance growth rate and lifetime of the proton beam is also estimated for the different scenarios.
Date: January 20, 2009
Creator: Abreu,N.P.; Fischer, W.; Luo, Y. & Robert-Demolaize, G.
Object Type: Report
System: The UNT Digital Library
Hanford Site Environmental Surveillance Master Sampling Schedule for Calendar Year 2009 (open access)

Hanford Site Environmental Surveillance Master Sampling Schedule for Calendar Year 2009

Environmental surveillance of the Hanford Site and surrounding areas is conducted by the Pacific Northwest National Laboratory for the U.S. Department of Energy. Sampling is conducted to evaluate levels of radioactive and nonradioactive pollutants in the Hanford environs, as required in DOE Order 450.1 and DOE Order 5400.5. This document contains the calendar year 2009 schedule for the routine collection of samples for the Surface Environmental Surveillance Project and Drinking Water Monitoring Project. Each section includes sampling locations, sampling frequencies, sample types, and analyses to be performed. In some cases, samples are scheduled on a rotating basis. If a sample will not be collected in 2009, the anticipated year for collection is provided. Maps showing approximate sampling locations are included for media scheduled for collection in 2009.
Date: January 20, 2009
Creator: Bisping, Lynn E.
Object Type: Report
System: The UNT Digital Library

Concentrating Photovoltaics

Solar is growing rapidly, and the concentrating photovoltaics industry-both high- and low-concentration cell approaches-may be ready to ramp production in 2009.
Date: January 20, 2009
Creator: Kurtz, S.
Object Type: Presentation
System: The UNT Digital Library
MEASUREMENT OF WIND SPEED FROM COOLING LAKE THERMAL IMAGERY (open access)

MEASUREMENT OF WIND SPEED FROM COOLING LAKE THERMAL IMAGERY

The Savannah River National Laboratory (SRNL) collected thermal imagery and ground truth data at two commercial power plant cooling lakes to investigate the applicability of laboratory empirical correlations between surface heat flux and wind speed, and statistics derived from thermal imagery. SRNL demonstrated in a previous paper [1] that a linear relationship exists between the standard deviation of image temperature and surface heat flux. In this paper, SRNL will show that the skewness of the temperature distribution derived from cooling lake thermal images correlates with instantaneous wind speed measured at the same location. SRNL collected thermal imagery, surface meteorology and water temperatures from helicopters and boats at the Comanche Peak and H. B. Robinson nuclear power plant cooling lakes. SRNL found that decreasing skewness correlated with increasing wind speed, as was the case for the laboratory experiments. Simple linear and orthogonal regression models both explained about 50% of the variance in the skewness - wind speed plots. A nonlinear (logistic) regression model produced a better fit to the data, apparently because the thermal convection and resulting skewness are related to wind speed in a highly nonlinear way in nearly calm and in windy conditions.
Date: January 20, 2009
Creator: Garrett, A; Robert Kurzeja, R; Eliel Villa-Aleman, E; Cary Tuckfield, C & Malcolm Pendergast, M
Object Type: Article
System: The UNT Digital Library
Prototype Testing for a Copper Rotatable Collimator for the LHC Collimation Upgrade (open access)

Prototype Testing for a Copper Rotatable Collimator for the LHC Collimation Upgrade

The Phase II upgrade to the LHC collimation system calls for complementing the robust Phase I graphite collimators with high Z Phase II collimators. The design for the collimation upgrade has not been finalized. One option is to use metallic rotatable collimators and testing of this design will be discussed here. The Phase II collimators must be robust in various operating conditions and accident scenarios. A prototype collimator jaw referred to as RC0 has been tested for both mechanical and thermal compliance with the design goals. Thermal expansion bench-top tests are compared to ANSYS simulation results. The prototype has also been tested in vacuum bake-out to confirm compliance with the LHC vacuum spec. CMM equipment has been used to verify the flatness of the jaw surface after heat tests and bake-out.
Date: January 20, 2009
Creator: Smith, Jeffrey Claiborne; Anzalone, Gene; Doyle, Eric; Keller, Lewis; Lundgren, Steven; Markiewicz, Thomas Walter et al.
Object Type: Report
System: The UNT Digital Library
Implementation Plans for a Systems Microbiology and Extremophile Research Facility (open access)

Implementation Plans for a Systems Microbiology and Extremophile Research Facility

Introduction Biological organisms long ago solved many problems for which scientists and engineers seek solutions. Microbes in particular offer an astonishingly diverse set of capabilities that can help revolutionize our approach to solving many important DOE problems. For example, photosynthetic organisms can generate hydrogen from light while simultaneously sequestering carbon. Others can produce enzymes that break down cellulose and other biomass to produce liquid fuels. Microbes in water and soil can capture carbon and store it in the earth and ocean depths. Understanding the dynamic interaction between living organisms and the environment is critical to predicting and mitigating the impacts of energy-production-related activities on the environment and human health. Collectively, microorganisms contain most of the biochemical diversity on Earth and they comprise nearly one-half of its biomass. They primary impact the planet by acting as catalysts of biogeochemical cycles; they capture light energy and fix CO2 in the worlds oceans, they degrade plant polymers and convert them to humus in soils, they weather rocks and facilitate mineral precipitation. Although the ability of selected microorganisms to participate in these processes is known, they rarely live in monoculture but rather function within communities. In spite of this, little is known about the …
Date: April 20, 2009
Creator: Wiley, H. S.
Object Type: Report
System: The UNT Digital Library
Synthesis and Characterization of Novel Preceramic Polymer for SiC (open access)

Synthesis and Characterization of Novel Preceramic Polymer for SiC

Polyphenylcarbosilane as a novel preceramic polymer for SiC was synthesized from thermal rearrangement of polymethylphenylsilane around 350 C {approx} 430 C. Characterization of synthesized polyphenylcarbosilane was performed with {sup 29}Si, {sup 13}C, {sup 1}H NMR, FT-IR, TG, XRD, and GPC analysis. From FT-IR data, the band at 1035 cm{sup -1} was very strong and assigned to CH{sub 2} bending vibration in Si-CH{sub 2}-Si group, indicating the formation of the polyphenylcarbosilane. The average of the molecular weight (M{sub w}) of the polyphenylcarbosilane synthesized was 2,500 and easily dissolves in an organic solvent. TGA data indicates that polyphenylcarbosilane is thermally stable up to 400 C. However, the rapid weight loss occurs above 400 C due to the pyrolysis of polyphenylcarbosilane, and the diffraction peak of pyrolysis residue at 1200 C corresponds to the {beta}-SiC ceramic. The ceramic yield calculated from TGA is approximately 65%.
Date: August 20, 2009
Creator: Lee, Y. J.; Lee, J. H.; Kim, S. R.; Kwon, W. T.; Oh, H.; Klepeis, J. P. et al.
Object Type: Article
System: The UNT Digital Library
Review and Analysis of Development of "Safety by Design" Requirements (open access)

Review and Analysis of Development of "Safety by Design" Requirements

This report, the deliverable for Task 4 of the NA-243 Safeguards by Design Work Plan for Fiscal Year 2009, develops the lessons to be learned for the institutionalization of Safeguards By Design (SBD) from the Department of Energy (DOE) experience developing and implementing DOE-STD-1189, Integration of Safety into the Design Process. This experience was selected for study because of the similarity of the challenges of integrating safety and safeguards into the design process. Development of DOE-STD-1189 began in January 2006 and the standard was issued for implementation in March 2008. The process was much more time consuming than originally anticipated and might not have come to fruition had senior DOE management been less committed to its success. Potentially valuable lessons can be learned from both the content and presentation of the integration approach in DOE-STD-1189 and from the DOE experience in developing and implementing DOE-STD-1189. These lessons are important because the instutionalization of SBD does not yet appear to have the level of senior management commitment afforded development and implementation of DOE-STD-1189.
Date: October 20, 2009
Creator: Vance, Scott A. & Hockert, John
Object Type: Report
System: The UNT Digital Library
Low Cost, Light Weight SOlar Modules Based on Organic Photovoltaic Technology (open access)

Low Cost, Light Weight SOlar Modules Based on Organic Photovoltaic Technology

Objectives - In order to produce solar modules for rooftop applications the performance and the lifetime must be improved to 5% - 7% and >10 year life. Task 1 Stability - (1) Flexible modules are stable to 1000 hrs at 65 C/85%RH, (2) Flexible modules in glass are stable to >2000 hrs at 85 C/85%RH (no decrease in performance); (3) Adhesive + filler helps stabilize modules; and (4) Solution coatable barriers exhibit good WVTR; work in-progress. Task 2 Performance: n-type charge carriers - (1) N-type polymers could not be synthesized; and (2) More than 30 fullerene derivatives synthesized and tested, Several deep LUMO derivatives accept charge from deep LUMO polymers, higher voltage observed, Improvement in cell efficiency not observed, morphology problem. Task 3 Performance: grid electrode - (1) Exceeded flatness and roughness goals; (2) Exceeds sheet resistance goals; (3) Achieved %T goals; and (4) Performance equivalent to ITO - 2% Efficiency ( av.); work in-progress.
Date: September 20, 2009
Creator: Gaudiana, Russell; GInley, David & Birkmeyer, Robert
Object Type: Report
System: The UNT Digital Library
Hydrogen Oxidation-Driven Hot Electron Flow Detected by Catalytic Nanodiodes (open access)

Hydrogen Oxidation-Driven Hot Electron Flow Detected by Catalytic Nanodiodes

Hydrogen oxidation on platinum is shown to be a surface catalytic chemical reaction that generates a steady state flux of hot (>1 eV) conduction electrons. These hot electrons are detected as a steady-state chemicurrent across Pt/TiO{sub 2} Schottky diodes whose Pt surface is exposed to hydrogen and oxygen. Kinetic studies establish that the chemicurrent is proportional to turnover frequency for temperatures ranging from 298 to 373 K for P{sub H2} between 1 and 8 Torr and P{sub O2} at 760 Torr. Both chemicurrent and turnover frequency exhibit a first order dependence on P{sub H2}.
Date: July 20, 2009
Creator: Hervier, Antoine; Renzas, J. Russell; Park, Jeong Y. & Somorjai, Gabor A.
Object Type: Article
System: The UNT Digital Library
VPP ANNUAL SELF-EVALUATION BY THE NUMBERS (open access)

VPP ANNUAL SELF-EVALUATION BY THE NUMBERS

None
Date: August 20, 2009
Creator: JE, GRIFFITH
Object Type: Article
System: The UNT Digital Library
Complete genome sequence of Dyadobacter fermentans type strain (NS114T) (open access)

Complete genome sequence of Dyadobacter fermentans type strain (NS114T)

Dyadobacter fermentans (Chelius MK and Triplett EW, 2000) is the type species of the genus Dyadobacter. It is of phylogenetic interest because of its location in the Cytophagaceae, a very diverse family within the order 'Sphingobacteriales'. D. fermentans has a mainly respiratory metabolism, stains Gram-negative, is non-motile and oxidase and catalase positive. It is characterized by the production of cell filaments in ageing cultures, a flexirubin-like pigment and its ability to ferment glucose, which is almost unique in the aerobically living members of this taxonomically difficult family. Here we describe the features of this organism, together with the complete genome sequence, and annotation. This is the first complete genome sequence of the 'sphingobacterial' genus Dyadobacter, and this 6,967,790 bp long single replicon genome with its 5804 protein-coding and 50 RNA genes is part of the Genomic Encyclopedia of Bacteria and Archaea project.
Date: May 20, 2009
Creator: Lang, Elke; Lapidus, Alla; Chertkov, Olga; Brettin, Thomas; Detter, John C.; Han, Cliff et al.
Object Type: Article
System: The UNT Digital Library
A Quick Guide to Wind Power Forecasting : State-Of-The-Art 2009. (open access)

A Quick Guide to Wind Power Forecasting : State-Of-The-Art 2009.

This document contains a summary of the main findings from our full report entitled 'Wind Power Forecasting: State-of-the-Art 2009'. The aims of this document are to provide guidelines and a quick overview of the current state-of-the-art in wind power forecasting (WPF) and to point out lines of research in the future development of forecasting systems.
Date: November 20, 2009
Creator: Monteiro, C.; Keko, H.; Bessa, R.; Miranda, V.; Botterud, A.; Wang, J. et al.
Object Type: Report
System: The UNT Digital Library

LCA of Parabolic Trough CSP: Materials Inventory and Embodied GHG Emissions from Two-Tank Indirect and Thermocline Thermal Storage

In the United States, concentrating solar power (CSP) is one of the most promising renewable energy (RE) technologies for reduction of electric sector greenhouse gas (GHG) emissions and for rapid capacity expansion. It is also one of the most price-competitive RE technologies, thanks in large measure to decades of field experience and consistent improvements in design. One of the key design features that makes CSP more attractive than many other RE technologies, like solar photovoltaics and wind, is the potential for including relatively low-cost and efficient thermal energy storage (TES), which can smooth the daily fluctuation of electricity production and extend its duration into the evening peak hours or longer. Because operational environmental burdens are typically small for RE technologies, life cycle assessment (LCA) is recognized as the most appropriate analytical approach for determining their environmental impacts of these technologies, including CSP. An LCA accounts for impacts from all stages in the development, operation, and decommissioning of a CSP plant, including such upstream stages as the extraction of raw materials used in system components, manufacturing of those components, and construction of the plant. The National Renewable Energy Laboratory (NREL) is undertaking an LCA of modern CSP plants, starting with those …
Date: July 20, 2009
Creator: Heath, Garvin; Burkhardt, John; Turchi, Craig; Decker, Terese & Kutscher, Chuck
Object Type: Presentation
System: The UNT Digital Library
Photoinduced Charge and Energy Transfer Processes in Molecular Aggregates (open access)

Photoinduced Charge and Energy Transfer Processes in Molecular Aggregates

This project involved the experimental probing of the electronic excited states generated by photoinduced (center-to-center) electron and energy transfer processes in several classes of transition metal donor/acceptor (D/A) complexes. Some of the general properties inferred from these studies should be useful in the design of new systems for energy conversion applications. Pursuit of the project goals has involved the determination of electron transfer efficiencies and the detailed study of variations in the electronic spectra of D/A complexes. This has resulted in the study of some very fundamental issues of photoinduced charge transfer and the identification of some of the constraints on its efficiency. The experimental studies of the competition between the degradative non-radiative unimolecular relaxation of transition metal excited states and their transfer of charge from these excited states to external acceptors have involved a range of techniques such as transient decay kinetics, photoacoustic calorimetry and transient or stationary state spectroscopy. The substrates synthesized for these studies were selected to provide model systems, or series of model systems to probe the validity of models of electronic excited states and their reactivity. The work during the last few years has focused largely, but not exclusively, on the use of emission spectral …
Date: October 20, 2009
Creator: Endicott, John F.
Object Type: Report
System: The UNT Digital Library
Thermal Analysis of SRF Cavity Couplers Using Parallel Multi physics Tool TEM3P (open access)

Thermal Analysis of SRF Cavity Couplers Using Parallel Multi physics Tool TEM3P

SLAC has developed a multi-physics simulation code TEM3P for simulating integrated effects of electromagnetic, thermal and structural loads. TEM3P shares the same software infrastructure with SLAC's parallel finite element electromagnetic codes, thus enabling all physics simulations within a single framework. The finite-element approach allows high-fidelity, high-accuracy simulations and the parallel implementation facilitates large-scale computation with fast turnaround times. In this paper, TEM3P is used to analyze thermal loading at coupler end of the JLAB SRF cavity.
Date: May 20, 2009
Creator: Akcelik, V; Lee, L. Q.; Li, Z.; Ng, C. K.; Ko, K.; Cheng, G. et al.
Object Type: Article
System: The UNT Digital Library
Lower Hybrid Heating and Current Drive on the Alcator C-Mod Tokamak (open access)

Lower Hybrid Heating and Current Drive on the Alcator C-Mod Tokamak

On the Alcator C-Mod tokamak, lower hybrid current drive (LHCD) is being used to modify the current profile with the aim of obtaining advanced tokamak (AT) performance in plasmas with parameters similar to those that would be required on ITER. To date, power levels in excess of 1 MW at a frequency of 4.6 GHz have been coupled into a variety of plasmas. Experiments have established that LHCD on C-Mod behaves globally as predicted by theory. Bulk current drive efficiencies, n20IlhR/Plh ~ 0.25, inferred from magnetics and MSE are in line with theory. Quantitative comparisons between local measurements, MSE, ECE and hard x-ray bremsstrahlung, and theory/simulation using the GENRAY, TORIC-LH CQL3D and TSC-LSC codes have been performed. These comparisons have demonstrated the off-axis localization of the current drive, its magnitude and location dependence on the launched n|| spectrum, and the use of LHCD during the current ramp to save volt-seconds and delay the peaking of the current profile. Broadening of the x-ray emission profile during ICRF heating indicates that the current drive location can be controlled by the electron temperature, as expected. In addition, an alteration in the plasma toroidal rotation profile during LHCD has been observed with a significant …
Date: November 20, 2009
Creator: R. Wilson, R. Parker, M. Bitter, P.T. Bonoli, C. Fiore, R.W. Harvey, K. Hill, A.E. Hubbard, J.W. Hughes, A. Ince-Cushman, C. Kessel, J.S. Ko, O. Meneghini, C.K. Phillips, M. Porkolab, J. Rice, A.E. Schmidt, S. Scott,S. Shiraiwa, E. Valeo, G.Wallace, J.C. Wright and the Alcator C-Mod Team
Object Type: Report
System: The UNT Digital Library
Search for Lepton Flavour Violating Decays Tau -> l Ks with the BABAR Detector (open access)

Search for Lepton Flavour Violating Decays Tau -> l Ks with the BABAR Detector

We present the search for the lepton flavour violating decay {tau} {yields} lK{sup 0}{sub s} with the BaBar experiment data. This process and many other lepton flavour violating {tau} decays, like {tau} {yields} {mu}{gamma} and {tau} {yields} lll, are one of the most promising channel to search for evidence of new physics. According to the Standard Model and the neutrino mixing parameters, branching fractions are estimated well below 10{sup -14}, but many models of new physics allow for branching fractions values close to the present experimental sensitivity. This analysis is based on a data sample of 469fb{sup -1} collected by BABAR detector at the PEP-II storage ring from 1999 to 2007, equivalent to 431 millions of {tau} pairs. the BABAR experiment, initially designed for studying CP violation in B mesons, has demonstrated to be one of the most suitable environments for studying {tau} decays. The tracking system, the calorimeter and the particle identification of BABAR, together with the knowledge of the {tau} initial energy, allow an extremely powerful rejection of background events that, for this analysis, is better than 10{sup -9}. Being {tau} {yields} lK{sup 0}{sub s} a decay mode without neutrinos, the signal {tau} decay can be fully reconstructed. …
Date: March 20, 2009
Creator: Cenci, Riccardo
Object Type: Thesis or Dissertation
System: The UNT Digital Library