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Non-Standard Physics in Leptonic and Semileptonic Decays of Charmed Mesons
Recent measurements of the branching fraction for D{sub s} {yields} {ell}v disagree with the Standard Model expectation, which relies on calculations of f{sub D{sub s}} from lattice QCD. This paper uses recent preliminary measurements from CLEO and a new preliminary lattice-QCD result from this conference to update the significance of the discrepancy. The 'f{sub D{sub s}} puzzle' stands now at 3.5{sigma}, with {sigma} predominantly from the statistical uncertainty of the experiments. New physics scenarios that could solve the puzzle would also lead to non-Standard amplitudes mediating the semileptonic decays D {yields} K{ell}v. This paper shows where the new amplitudes enter the differential rate and outlines where lattice QCD calculations are needed to confront recent and forthcoming measurements.
Date:
December 1, 2008
Creator:
Kronfeld, Andreas S.
Object Type:
Article
System:
The UNT Digital Library
Carbonyl Emissions from Gasoline and Diesel Motor Vehicles
Carbonyls from gasoline powered light-duty vehicles (LDVs) and heavy-duty diesel powered vehicles (HDDVs) operated on chassis dynamometers were measured using an annular denuder-quartz filter-polyurethane foam sampler with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine derivatization and chromatography-mass spectrometry analyses. Two internal standards were utilized based on carbonyl recovery, 4-fluorobenzaldehyde for<C8 carbonyls and 6-fluoro-4-chromanone for>_C8 compounds. Gas- and particle-phase emissions for 39 aliphatic and 20 aromatic carbonyls ranged from 0.1 ? 2000 ?g/L fuel for LDVs and 1.8 - 27000 mu g/L fuel for HDDVs. Gas-phase species accounted for 81-95percent of the total carbonyls from LDVs and 86-88percent from HDDVs. Particulate carbonyls emitted from a HDDV under realistic driving conditions were similar to concentrations measured in a diesel particulate matter (PM) standard reference material. Carbonyls accounted for 19percent of particulate organic carbon (POC) emissions from low-emission LDVs and 37percent of POC emissions from three-way catalyst equipped LDVs. This identifies carbonyls as one of the largest classes of compounds in LDV PM emissions. The carbonyl fraction of HDDV POC was lower, 3.3-3.9percent depending upon operational conditions. Partitioning analysis indicates the carbonyls had not achieved equilibrium between the gas- and particle-phase under the dilution factors of 126-584 used in the current study.
Date:
December 1, 2007
Creator:
Destaillats, Hugo; Jakober, Chris A.; Robert, Michael A.; Riddle, Sarah G.; Destaillats, Hugo; Charles, M. Judith et al.
Object Type:
Article
System:
The UNT Digital Library
Meso-scale controlled motion for a microfluidic drop ejector.
The objective of this LDRD was to develop a uniquely capable, novel droplet solution based manufacturing system built around a new MEMS drop ejector. The development all the working subsystems required was completed, leaving the integration of these subsystems into a working prototype still left to accomplish. This LDRD report will focus on the three main subsystems: (1) MEMS drop ejector--the MEMS ''sideshooter'' effectively ejected 0.25 pl drops at 10 m/s, (2) packaging--a compact ejector package based on a modified EMDIP (Electro-Microfluidic Dual In-line Package--SAND2002-1941) was fabricated, and (3) a vision/stage system allowing precise ejector package positioning in 3 dimensions above a target was developed.
Date:
December 1, 2004
Creator:
Galambos, Paul C.; Givler, Richard C.; Pohl, Kenneth Roy; Czaplewski, David A.; Luck, David L.; Braithwaite, Mark J. et al.
Object Type:
Report
System:
The UNT Digital Library
Self-organized T(sub)e Redistribution during Driven Reconnection Processes in High Temperature Plasmas
Two-dimensional (2-D) images of electron temperature fluctuations with a high temporal and spatial resolution were employed to study the sawtooth oscillation in TEXTOR tokamak plasmas. The new findings are: 1) 2-D images revealed that the reconnection is localized and permitted the determination of the physical dimensions of the reconnection zone in the poloidal and toroidal planes. 2) The combination of a pressure driven mode and a kink instability leads to an "X-point" reconnection process. 3) Reconnection can take place anywhere along the q~1 rational magnetic surface (both high and low field sides). 4) Heat flow from the core to the outside of the inversion radius during the reconnection time is highly asymmetric and the behavior is collective. These new findings are compared with the characteristics of various theoretical models and experimental results for the study of the sawtooth oscillation in tokamak plasmas.
Date:
December 1, 2005
Creator:
Park, H. K.; Mazzucato, E.; Luhmann, N. C. Jr.; Domier, C. W.; Xia, Z.; Munsat, T. et al.
Object Type:
Report
System:
The UNT Digital Library
Lipid membranes on nanostructured silicon.
A unique composite nanoscale architecture that combines the self-organization and molecular dynamics of lipid membranes with a corrugated nanotextured silicon wafer was prepared and characterized with fluorescence microscopy and scanning probe microscopy. The goal of this project was to understand how such structures can be assembled for supported membrane research and how the interfacial interactions between the solid substrate and the soft, self-assembled material create unique physical and mechanical behavior through the confinement of phases in the membrane. The nanometer scale structure of the silicon wafer was produced through interference lithography followed by anisotropic wet etching. For the present study, a line pattern with 100 nm line widths, 200 nm depth and a pitch of 360 nm pitch was fabricated. Lipid membranes were successfully adsorbed on the structured silicon surface via membrane fusion techniques. The surface topology of the bilayer-Si structure was imaged using in situ tapping mode atomic force microscopy (AFM). The membrane was observed to drape over the silicon structure producing an undulated topology with amplitude of 40 nm that matched the 360 nm pitch of the silicon structure. Fluorescence recovery after photobleaching (FRAP) experiments found that on the microscale those same structures exhibit anisotropic lipid mobility that …
Date:
December 1, 2004
Creator:
Slade, Andrea Lynn; Lopez, Gabriel P. (University of New Mexico, Albuquerque, NM); Ista, Linnea K. (University of New Mexico, Albuquerque, NM); O'Brien, Michael J. (University of New Mexico, Albuquerque, NM); Sasaki, Darryl Yoshio; Bisong, Paul (University of New Mexico, Albuquerque, NM) et al.
Object Type:
Report
System:
The UNT Digital Library
Accelerating PV Cost Effectiveness Through Systems Design, Engineering, and Quality Assurance: Final Subcontract Report, June 2007
This report describes PowerLight Corporation's significant progress toward the reduction of installed costs for commercial-scale, rooftop PV systems.
Date:
December 1, 2007
Creator:
Botkin, J.
Object Type:
Report
System:
The UNT Digital Library
Revolutionary systems for catalytic combustion and diesel catalytic particulate traps.
This report is a summary of an LDRD project completed for the development of materials and structures conducive to advancing the state of the art for catalyst supports and diesel particulate traps. An ancillary development for bio-medical bone scaffolding was also realized. Traditionally, a low-pressure drop catalyst support, such as a ceramic honeycomb monolith, is used for catalytic reactions that require high flow rates of gases at high-temperatures. A drawback to the traditional honeycomb monoliths under these operating conditions is poor mass transfer to the catalyst surface in the straight-through channels. ''Robocasting'' is a unique process developed at Sandia National Laboratories that can be used to manufacture ceramic monoliths with alternative 3-dimensional geometries, providing tortuous pathways to increase mass transfer while maintaining low-pressure drops. These alternative 3-dimensional geometries may also provide a foundation for the development of self-regenerating supports capable of trapping and combusting soot particles from a diesel engine exhaust stream. This report describes the structures developed and characterizes the improved catalytic performance that can result. The results show that, relative to honeycomb monolith supports, considerable improvement in mass transfer efficiency is observed for robocast samples synthesized using an FCC-like geometry of alternating rods. Also, there is clearly a …
Date:
December 1, 2004
Creator:
Stuecker, John Nicholas; Witze, Peter O.; Ferrizz, Robert Matthew; Cesarano, Joseph, III & Miller, James Edward
Object Type:
Report
System:
The UNT Digital Library
Regional Per Capita Solar Electric Footprint for the United States
In this report, we quantify the state-by-state per-capita 'solar electric footprint' for the United States. We use state-level data on population, electricity consumption, economic activity and solar insolation, along with solar photovoltaic (PV) array packing density data to develop a range of estimates of the solar electric footprint. We find that the solar electric footprint, defined as the land area required to supply all end-use electricity from solar photovoltaics, is about 181 m2 per person in the United States. Two key factors that influence the magnitude of the state-level solar electric footprint include how industrial energy is allocated (based on location of use vs. where goods are consumed) and the assumed distribution of PV configurations (flat rooftop vs. fixed tilt vs. tracking). The solar electric footprint is about 0.6% of the total land area of the United States with state-level estimates ranging from less than 0.1% for Wyoming to about 9% for New Jersey. We also compare the solar electric footprint to a number of other land uses. For example, we find that the solar electric footprint is equal to less than 2% of the land dedicated to cropland and grazing in the United States.
Date:
December 1, 2007
Creator:
Denholm, P. & Margolis, R.
Object Type:
Report
System:
The UNT Digital Library
Operation of a Segmented Hall Thruster with Low-sputtering Carbon-velvet Electrodes
Carbon fiber velvet material provides exceptional sputtering resistance properties exceeding those for graphite and carbon composite materials. A 2 kW Hall thruster with segmented electrodes made of this material was operated in the discharge voltage range of 200–700 V. The arcing between the floating velvet electrodes and the plasma was visually observed, especially, during the initial conditioning time, which lasted for about 1 h. The comparison of voltage versus current and plume characteristics of the Hall thruster with and without segmented electrodes indicates that the magnetic insulation of the segmented thruster improves with the discharge voltage at a fixed magnetic field. The observations reported here also extend the regimes wherein the segmented Hall thruster can have a narrower plume than that of the conventional nonsegmented thruster.
Date:
December 1, 2005
Creator:
Raitses, Y.; Staack, D.; Dunaevsky, A. & Fisch, N. J.
Object Type:
Report
System:
The UNT Digital Library
Measurement of Lifetime and Decay-Width Difference in B0s -> J/psi phi Decays
The authors measure the mean lifetime, {tau} = 2/({Lambda}{sub L} + {Lambda}{sub H}), and the decay-width difference, {Delta}{Lambda} = {Lambda}{sub L} - {Lambda}{sub H}, of the light and heavy mass eigenstates of the B{sub s}{sup 0} meson, B{sub sL}{sup 0} and B{sub sH}{sup 0}, in B{sub s}{sup 0} {yields} J/{psi}{phi} decays using 1.7 fb{sup -1} of data collected with the CDF II detector at the Fermilab Tevatron p{bar p} collider. Assuming CP conservation, a good approximation for the B{sub s}{sup 0} system in the standard model, they obtain {Delta}{Lambda} = 0.076{sub -0.063}{sup +0.059}(stat.) {+-} 0.006(syst.) ps{sup -1} and {tau} = 1.52 {+-} 0.04(stat.) {+-} 0.02(syst.) ps, the most precise measurements to date. The constraints on the weak phase and {Delta}{Lambda} are consistent with CP conservation.
Date:
December 1, 2007
Creator:
Aaltonen, : T.
Object Type:
Article
System:
The UNT Digital Library
Expanding the Limits of CdTe PV Performance: Phase I Annual Report, 7 February 2006 - 30 June 2007
First Solar made 9 CdTe PV devices; found two front- and one back-side structures that show improved Jsc and Voc, respectively, compared to base device structure; best cell efficiency was 14.13%.
Date:
December 1, 2007
Creator:
Meyers, P.
Object Type:
Report
System:
The UNT Digital Library
Global Assessment of Hydrogen Technologies – Task 5 Report Use of Fuel Cell Technology in Electric Power Generation
The purpose of this work was to assess the performance of high temperature membranes and observe the impact of different parameters, such as water-to-carbon ratio, carbon formation, hydrogen formation, efficiencies, methane formation, fuel and oxidant utilization, sulfur reduction, and the thermal efficiency/electrical efficiency relationship, on fuel cell performance. A 250 KW PEM fuel cell model was simulated [in conjunction with Argonne National Laboratory (ANL) with the help of the fuel cell computer software model (GCtool)] which would be used to produce power of 250 kW and also produce steam at 120oC that can be used for industrial applications. The performance of the system was examined by estimating the various electrical and thermal efficiencies achievable, and by assessing the effect of supply water temperature, process water temperature, and pressure on thermal performance. It was concluded that increasing the fuel utilization increases the electrical efficiency but decreases the thermal efficiency. The electrical and thermal efficiencies are optimum at ~85% fuel utilization. The low temperature membrane (70oC) is unsuitable for generating high-grade heat suitable for useful cogeneration. The high temperature fuel cells are capable of producing steam through 280oC that can be utilized for industrial applications. Increasing the supply water temperature reduces the …
Date:
December 1, 2007
Creator:
Fouad, Fouad H.; Peters, Robert W.; Sisiopiku, Virginia P.; J., Sullivan Andrew & Ahluwalia, Rajesh K.
Object Type:
Report
System:
The UNT Digital Library
Surface Specularity as an Indicator of Shock-induced Solid-liquid Phase Transitions in Tin
When highly polished metal surfaces melt upon release after shock loading, they exhibit features that suggest significant surface changes accompany the phase transition. The reflection of light from such surfaces changes from specular (pre-shock) to diffuse upon melting. Typical of this phenomenon is the loss of signal light in velocity interferometer system for any reflector (VISAR) measurements, which usually occurs at pressures high enough to melt the free surface. Unlike many other potential material phase-sensitive diagnostics (e.g., reflectometry, conductivity), that show relatively small (1%-10%) changes, the specularity of reflection provides a more sensitive and definitive (>10x) indication of the solid-liquid phase transition. Data will be presented that support the hypothesis that specularity changes indicate melt in a way that can be measured easily and unambiguously.
Date:
December 1, 2007
Creator:
G. D. Stevens, S. S. Lutz, B. R. Marshall, W.D. Turley, et al.
Object Type:
Article
System:
The UNT Digital Library
Initial Business Case Analysis of Two Integrated Heat Pump HVAC Systems for Near-Zero-Energy Homes -- Update to Include Analyses of an Economizer Option and Alternative Winter Water Heating Control Option
The long range strategic goal of the Department of Energy's Building Technologies (DOE/BT) Program is to create, by 2020, technologies and design approaches that enable the construction of net-zero energy homes at low incremental cost (DOE/BT 2005). A net zero energy home (NZEH) is a residential building with greatly reduced needs for energy through efficiency gains, with the balance of energy needs supplied by renewable technologies. While initially focused on new construction, these technologies and design approaches are intended to have application to buildings constructed before 2020 as well resulting in substantial reduction in energy use for all building types and ages. DOE/BT's Emerging Technologies (ET) team is working to support this strategic goal by identifying and developing advanced heating, ventilating, air-conditioning, and water heating (HVAC/WH) technology options applicable to NZEHs. Although the energy efficiency of heating, ventilating, and air-conditioning (HVAC) equipment has increased substantially in recent years, new approaches are needed to continue this trend. Dramatic efficiency improvements are necessary to enable progress toward the NZEH goals, and will require a radical rethinking of opportunities to improve system performance. The large reductions in HVAC energy consumption necessary to support the NZEH goals require a systems-oriented analysis approach that characterizes …
Date:
December 1, 2006
Creator:
Baxter, Van D
Object Type:
Report
System:
The UNT Digital Library
A Measurement of the muon neutrino charged current quasielastic interaction and a test of Lorentz violation with the MiniBooNE experiment
The Mini-Booster neutrino experiment (MiniBooNE) at Fermi National Accelerator Laboratory (Fermilab) is designed to search for {nu}{sub {mu}} {yields} {nu}{sub e} appearance neutrino oscillations. Muon neutrino charged-current quasi-elastic (CCQE) interactions ({nu}{sub {mu}} + n {yields} {mu} + p) make up roughly 40% of our data sample, and it is used to constrain the background and cross sections for the oscillation analysis. Using high-statistics MiniBooNE CCQE data, the muon-neutrino CCQE cross section is measured. The nuclear model is tuned precisely using the MiniBooNE data. The measured total cross section is {sigma} = (1.058 {+-} 0.003 (stat) {+-} 0.111 (syst)) x 10{sup -38} cm{sup 2} at the MiniBooNE muon neutrino beam energy (700-800 MeV). {nu}{sub e} appearance candidate data is also used to search for Lorentz violation. Lorentz symmetry is one of the most fundamental symmetries in modern physics. Neutrino oscillations offer a new method to test it. We found that the MiniBooNE result is not well-described using Lorentz violation, however further investigation is required for a more conclusive result.
Date:
December 1, 2008
Creator:
Katori, Teppei
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Measurements of CP asymmetries and branching fractions of two-body charmless decays of B^0 and B^0_s mesons
The thesis is organized as follows: Chapter 1 describes the theoretical framework of non-leptonic B{sub (s)}{sup 0} {yields} H{sup +}h{prime}{sup -} decays, with a simple overview of the CP violation mechanism within the Standard Model and of the most used phenomenological approaches in the evaluation of strong interaction contributions. The chapter contains also a review of the theoretical expectations and the current experimental measurements along with a discussion about the importance of studying such decays. Chapter 2 contains a general description of the Tevatron collider and of the CDF II detector. Chapter 3 is devoted to the description of the data sample used for the measurement and the method used in extracting the signal from the background. Particular attention is dedicated to the on-line trigger selection, which is crucial to collect a sample enriched in B{sub (s)}{sup 0} {yields} h{sup +}h{prime}{sup -} decays. Chapter 4 shows how the information from kinematics and particle identification was used to achieve a statistical discrimination amongst modes to extract individual measurements. The available resolutions in mass or in particle identification are separately insufficient for an event-by-event separation of B{sub (s)}{sup 0} {yields} h{sup +}h{prime}{sup -} modes. The choice of observables and the technique used …
Date:
December 1, 2007
Creator:
Morello, Michael Joseph & /Pisa, Scuola Normale Superiore
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
HyPro: A Financial Tool for Simulating Hydrogen Infrastructure Development, Final Report
This report summarizes a multi-year Directed Technologies Inc. (DTI) project to study the build-out of hydrogen production facilities during the transition from gasoline internal combustion engine vehicle to hydrogen fuel cell vehicles. The primary objectives of the project are to develop an enhanced understanding of hydrogen production issues during the transition period (out to 2050) and to develop recommendations for the DOE on areas of further study. These objectives are achieved by conducting economic and scenario analysis to predict how industry would provide the hydrogen production, delivery and dispensing capabilities necessary to satisfy increased hydrogen demand. The primary tool used for the analysis is a custom created MatLab simulation tool entitled HyPro (short for Hydrogen Production). This report describes the calculation methodology used in HyPro, the baseline assumptions, the results of the baseline analysis and several corollary studies. The appendices of this report included a complete listing of model assumptions (capital costs, efficiencies, feedstock prices, delivery distances, etc.) and a step-by-step manual on the specific operation of the HyPro program. This study was made possible with funding from the U.S. Department of Energy (DOE).
Date:
December 1, 2008
Creator:
Brian D. James, Peter O. Schmidt, Julie Perez
Object Type:
Report
System:
The UNT Digital Library
Accuracy of Analog Fiber-Optic Links in Pulsed Radiation Environments
Interferometric fiber-optic links used in pulsed-power experiments are evaluated for accuracy in the presence of radiation fields which alter fiber transmission. Amplitude-modulated format (e.g., Mach-Zehnder) and phase-modulated formats are compared. Historically, studies of radiation effects on optical fibers have focused on degradation and recovery of the fibers transmission properties; such work is either in the context of survivability of fibers in catastrophic conditions or suitability of fibers installed for command and control systems within an experimental facility [1], [2]. In this work, we consider links used to transmit realtime diagnostic data, and we analyze the error introduced by radiation effects during the drive pulse. The result is increased uncertainties in key parameters required to unfold the sinusoidal transfer function. Two types of modulation are considered: amplitude modulation typical of a Mach-Zehnder (M-Z) modulator [3], and phase modulation, which offers more flexible demodulation options but relies on the spatiotemporal coherence of the light in the fiber. The M-Z link is shown schematically in Fig. 1, and the phase-modulated link is shown in Fig. 2. We present data from two experimental environments: one with intense, controlled radiation fields to simulate conditions expected at the next generation of pulsed-power facilities, and the second …
Date:
December 1, 2007
Creator:
E. K. Miller, G. S. Macrum, I. J. McKenna, et al.
Object Type:
Article
System:
The UNT Digital Library
Historical Analysis of Investment in Solar Energy Technologies (2000-2007)
The solar energy industry experienced unprecedented growth in the eight years from 2000 to 2007, with explosive growth occurring in the latter half of this period. From 2004 to 2007, global private sector investment in solar energy increased by almost twenty-fold, marking a dramatic increase in the short span of four years. This paper examines the timing, magnitude, focus and location of various forms of investment in the solar energy sector. It analyzes their trends to provide an understanding of the growth of the solar industry during the past eight years and to identify emerging themes in this rapidly evolving industry.
Date:
December 1, 2008
Creator:
Jennings, C. E.; Margolis, R. M. & Bartlett, J. E.
Object Type:
Report
System:
The UNT Digital Library
A digital accelerometer array utilizing suprathreshold stochastic resonance for detection of sub-Brownian noise floor accelerations.
The goal of this LDRD project was to evaluate the possibilities of utilizing Stochastic resonance in micromechanical sensor systems as a means for increasing signal to noise for physical sensors. A careful study of this field reveals that in the case of a single sensing element, stochastic resonance offers no real advantage. We have, however, identified a system that can utilize very similar concepts to stochastic resonance in order to achieve an arrayed sensor system that could be superior to existing technologies in the field of inertial sensors, and could offer a very low power technique for achieving navigation grade inertial measurement units.
Date:
December 1, 2004
Creator:
Carr, Dustin Wade & Olsson, Roy H.
Object Type:
Report
System:
The UNT Digital Library
Parametric Gasification of Oak and Pine Feedstocks Using the TCPDU and Slipstream Water-Gas Shift Catalysis
With oak and pine feedstocks, the Gasification of Biomass to Hydrogen project maximizes hydrogen production using the Full Stream Reformer during water-gas shift fixed-bed reactor testing. Results indicate that higher steam-to-biomass ratio and higher thermal cracker temperature yield higher hydrogen concentration. NREL's techno-economic models and analyses indicate hydrogen production from biomass may be viable at an estimated cost of $1.77/kg (current) and $1.47/kg (advanced in 2015). To verify these estimates, NREL used the Thermochemical Process Development Unit (TCPDU), an integrated system of unit operations that investigates biomass thermochemical conversion to gaseous and liquid fuels and chemicals.
Date:
December 1, 2008
Creator:
Hrdlicka, J.; Feik, C.; Carpenter, D. & Pomeroy, M.
Object Type:
Report
System:
The UNT Digital Library
MEMS solar energy harvesting.
None
Date:
December 1, 2007
Creator:
Nielson, Gregory N.; Resnick, Paul James; Epp, David S.; Gupta, Vipin P.; Wittwer, Jonathan W.; Phinney, Leslie Mary et al.
Object Type:
Report
System:
The UNT Digital Library
Battery Technology Life Verification Testing and Analysis
A critical component to the successful commercialization of batteries for automotive applications is accurate life prediction. The Technology Life Verification Test (TLVT) Manual was developed to project battery life with a high level of statistical confidence within only one or two years of accelerated aging. The validation effort that is presently underway has led to several improvements to the original methodology. For example, a newly developed reference performance test revealed a voltage path dependence effect on resistance for lithium-ion cells. The resistance growth seems to depend on how a target condition is reached (i.e., by a charge or a discharge). Second, the methodology for assessing the level of measurement uncertainty was improved using a propagation of errors in the fundamental measurements to the derived response (e.g., resistance). This new approach provides a more realistic assessment of measurement uncertainty. Third, the methodology for allocating batteries to the test matrix has been improved. The new methodology was developed to assign batteries to the matrix such that the average of each test group would be representative of the overall population. These changes to the TLVT methodology will help to more accurately predict a battery technology’s life capability with a high degree of confidence.
Date:
December 1, 2007
Creator:
Christophersen, Jon P.; Hunt, Gary L.; Bloom, Ira; Thomas, Ed & Battaglia, Vince
Object Type:
Article
System:
The UNT Digital Library
Upper limit on the diffuse flux of UHE tau neutrinos from the Pierre Auger Observatory
The surface detector array of the Pierre Auger Observatory is sensitive to Earth-skimming tau-neutrinos {nu}{sub {tau}} that interact in the Earth's crust. Tau leptons from {tau}{sub {tau}} charged-current interactions can emerge and decay in the atmosphere to produce a nearly horizontal shower with a significant electromagnetic component. The data collected between 1 January 2004 and 31 August 2007 is used to place an upper limit on the diffuse flux of {nu}{sub {tau}} at EeV energies. Assuming an E{sub {nu}}{sup -2} differential energy spectrum the limit set at 90 % C.L. is E{sub {nu}}{sup 2} dN{sub {nu}{sub {tau}}}/dE{sub {nu}} < 1.3 x 10{sup -7} GeV cm{sup -2} s{sup -1} sr{sup -1} in the energy range 2 x 10{sup 17} eV < E{sub {nu}} < 2 x 10{sup 19} eV.
Date:
December 1, 2007
Creator:
Collaboration, The Pierre Auger
Object Type:
Article
System:
The UNT Digital Library