Near Threshold electroproduction of the Omega Meson at Momentum Transfer Q2=0.5 (GeV/c)2 (open access)

Near Threshold electroproduction of the Omega Meson at Momentum Transfer Q2=0.5 (GeV/c)2

Jefferson Lab kaon experiments E91016/E93018 produced data on both strangeness and vector meson electroproduction. The latter part of the experiments was focused on the electroproduction of the omega meson for momentum transfer Q 2 near 0.5 (GeV/c) 2. This reaction was selected from the inelastic ep channel, H-1 (e, e' p)X, by performing involved signal background separation. Tagging the omega meson production only on electron and proton not only introduced appreciable statistical error but also a sizeable systematic uncertainty due to the background removal. Nevertheless, the analysis yielded angular distributions of the differential cross section in the threshold regime extracted with an unprecedented granularity and relatively small errors.
Date: January 1, 2002
Creator: Ambrosewicz, P.
System: The UNT Digital Library
Large-Eddy Simulation of the Evolving Stable Boundary Layer Over Flat Terrain (open access)

Large-Eddy Simulation of the Evolving Stable Boundary Layer Over Flat Terrain

The stable boundary layer (SBL) in the atmosphere is of considerable interest because it is often the worse case scenario for air pollution studies and health effect assessments associated with the accidental release of toxic material. Traditional modeling approaches used in such studies do not simulate the non-steady character of the velocity field, and hence often overpredict concentrations while underpredicting spatial coverage of potentially harmful concentrations of airborne material. The challenge for LES is to be able to resolve the rather small energy-containing eddies of the SBL while still maintaining an adequate domain size. This requires that the subgrid-scale (SGS) parameterization of turbulence incorporate an adequate representation of turbulent energy transfer. Recent studies have shown that both upscale and downscale energy transfer can occur simultaneously, but that overall the net transfer is downscale. Including the upscale transfer of turbulent energy (energy backscatter) is particularly important near the ground and under stably-stratified conditions. The goal of this research is to improve the ability to realistically simulate the SBL. The large-eddy simulation (LES) approach with its subgrid-scale (SGS) turbulence model does a better job of capturing the temporally and spatially varying features of the SBL than do Reynolds-averaging models. The scientific objectives …
Date: January 2, 2002
Creator: Townsend, Richard Townsend
System: The UNT Digital Library
A study of B(s)0 to J/psi phi in the D0 experiment and an example of HEP technology transfer (open access)

A study of B(s)0 to J/psi phi in the D0 experiment and an example of HEP technology transfer

After years of preparation, data taking with the upgraded D0 detector at the Tevatron proton-antiproton collider has begun. The large amount of data produced in a p{bar p}-collider requires sophisticated triggers to filter out the interesting events. Described in this thesis is the development of trigger software for the newly implemented Silicon Microstrip Tracker. D0 is a multi-purpose detector with a broad physics program. one area being studied at D0 is B mesons. An algorithm for reconstructing the B{sub s}{sup 0} and B{sub d}{sup 0} mesons and for measuring their lifetimes has been developed and is described in this thesis. The results suggest that an improvement of the current lifetime measurements can be achieved within the next two years. The reconstruction of a J/{psi} meson forms the basis for a wide range of b-physics. Data taken with the muon system during the commissioning period of the detector has been analyzed and a signal for the J/{psi} meson has been found. Systematic transfer of HEP technologies into other areas and their commercial exploitation plays an important role in the future of particle physics. An area of particular interest is DNA sequencing as shown by the recent completion of the sequencing of …
Date: January 1, 2002
Creator: Bauer, Daniela Ursula
System: The UNT Digital Library
Development of trigger software for the silicon and fibre trackers and a study of B meson lifetimes for the D0 experiment (open access)

Development of trigger software for the silicon and fibre trackers and a study of B meson lifetimes for the D0 experiment

The D0 detector has recently undergone a major upgrade to maximize its potential to fully exploit Run II at the Tevatron 2 TeV proton-antiproton collider. The upgrade includes a completely new central tracking system with an outer scintillating fiber tracker and an inner silicon vertex detector. This thesis describes the development of the software to ''unpack'' the raw data from the central tracking detectors into a useful form, and the development of the Level 3 trigger algorithms to cluster the hit information from these detectors. One of the many areas of physics that is being studied by the D0 experiment is the physics of B mesons, particularly that involving CP violation. The second part of the thesis details a constrained mass fitting tool written to aid the reconstruction of B particles, and a Monte Carlo study into measuring the lifetime of B{sup +} and B{sup 0} mesons. This thesis lays the foundations for the means by which physics is extracted from the vast amount of Tevatron data--the trigger--and illustrates how analyses will proceed through the key reconstruction of heavy quarks.
Date: January 1, 2002
Creator: Illingworth, Robert Arthur
System: The UNT Digital Library