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A search for neutral supersymmetric Higgs bosons and work relating to the improvement of the b-tagging and trigger capabilities at the D0 detector during Run II of the Fermilab Tevatron collider is presented. The search for evidence of the Higgs sector in the Standard Model (SM) and supersymmetric extensions of the SM are a high priority for the D0 collaboration, and b-tagging and good triggers are a vital component of these searches. The development and commissioning of the first triggers at D0 which use b-tagging is outlined, along with the development of a new secondary vertex b-tagging tool for use in the Level 3 trigger. Upgrades to the Level 3 trigger hit finding code, which have led to significant improvements in the quality and efficiency of the tracking code, and by extension the b-tagging tools, are also presented. An offline Neural Network (NN) b-tagging tool was developed, trained on Monte Carlo and extensively tested and measured on data. The new b-tagging tool significantly improves the b-tagging performance at D0, for a fixed fake rate relative improvements in signal efficiency range from {approx} 40% to {approx} 15%. Fake rates, for a fixed signal efficiency, are typically reduced to between a quarter …

The renaissance of Extreme Ultraviolet (EUV) and soft x-ray (SXR) optics in recent years is mainly driven by the desire of printing and observing ever smaller features, as in lithography and microscopy. This attribute is complemented by the unique opportunity for element specific identification presented by the large number of atomic resonances, essentially for all materials in this range of photon energies. Together, these have driven the need for new short-wavelength radiation sources (e.g. third generation synchrotron radiation facilities), and novel optical components, that in turn permit new research in areas that have not yet been fully explored. This dissertation is directed towards advancing this new field by contributing to the characterization of spatial coherence properties of undulator radiation and, for the first time, introducing Fourier optical elements to this short-wavelength spectral region. The first experiment in this dissertation uses the Thompson-Wolf two-pinhole method to characterize the spatial coherence properties of the undulator radiation at Beamline 12 of the Advanced Light Source. High spatial coherence EUV radiation is demonstrated with appropriate spatial filtering. The effects of small vertical source size and beamline apertures are observed. The difference in the measured horizontal and vertical coherence profile evokes further theoretical studies on …

An analysis of completed decommissioning projects is used to construct predictive estimates for worker exposure to radioactivity during decommissioning activities. The preferred organizational method for the completed decommissioning project data is to divide the data by type of facility, whether decommissioning was performed on part of the facility or the complete facility, and the level of radiation within the facility prior to decommissioning (low, medium, or high). Additional data analysis shows that there is not a downward trend in worker exposure data over time. Also, the use of a standard estimate for worker exposure to radioactivity may be a best estimate for low complete storage, high partial storage, and medium reactor facilities; a conservative estimate for some low level of facility radiation facilities (reactor complete, research complete, pits/ponds, other), medium partial process facilities, and high complete research facilities; and an underestimate for the remaining facilities. Limited data are available to compare different decommissioning alternatives, so the available data are reported and no conclusions can been drawn. It is recommended that all DOE sites and the NRC use a similar method to document worker hours, worker exposure to radiation (person-rem), and standard industrial accidents, injuries, and deaths for all completed decommissioning …

The D0 detector underwent an upgrade to its silicon vertex detector and triggering systems during the transition from Run IIa to Run IIb to maximize its ability to fully exploit Run II at the Fermilab Tevatron. This thesis describes improvements made to the tracking and vertexing algorithms used by the high level trigger in both Run IIa and Run IIb, as well as a search for resonant di-J/{psi} states using both Run IIa and Run IIb data. Improvements made to the tracking and vertexing algorithms during Run IIa included the optimization of the existing tracking software to reduce overall processing time and the certification and testing of a new software release. Upgrades made to the high level trigger for Run IIb included the development of a new tracking algorithm and the inclusion of the new Layer 0 silicon detector into the existing software. The integration of Layer 0 into the high level trigger has led to an improvement in the overall impact parameter resolution for tracks of {approx}50%. The development of a new parameterization method for finding the error associated to the impact parameter of tracks returned by the high level tracking algorithm, in association with the inclusion of Layer …

This dissertation describes a direct measurement of the W boson total decay width, {Lambda}{sub W}, using the D0 detector at the Fermilab Tevatron Collider. The measurement uses an integrated luminosity of 177.3 pb{sup -1} data, collected during the 2002-2003 run. The width is determined from the shape of the transverse mass distribution, M{sub T}, by fitting the data in the tail region 100 < M{sub T} < 200 GeV. The result if {Lambda}{sub W} = 2.011 {+-} 0.093(stat) {+-} 0.107(syst) GeV.

Magnetic monopoles are highly ionizing and curve in the direction of the magnetic field. A new dedicated magnetic monopole trigger at CDF, which requires large light pulses in the scintillators of the time-of-flight system, remains highly efficient to monopoles while consuming a tiny fraction of the available trigger bandwidth. A specialized offline reconstruction checks the central drift chamber for large dE/dx tracks which do not curve in the plane perpendicular to the magnetic field. We observed zero monopole candidate events in 35.7 pb{sup -1} of proton-antiproton collisions at {radical}s = 1.96 TeV. This implies a monopole production cross section limit {sigma} < 0.2 pb for monopoles with mass between 100 and 700 GeV, and, for a Drell-Yan like pair production mechanism, a mass limit m > 360 GeV.

In May 2000, the Cerro Grande Fire burned approximately 17,200 ha in north-central New Mexico as the result of an escaped prescribed burn initiated by Bandelier National Monument. The interaction of large-scale fires, vegetation, and elk is an important management issue, but few studies have addressed the ecological implications of vegetative succession and landscape heterogeneity on ungulate populations following large-scale disturbance events. Primary objectives of this research were to identify elk movement pathways on local and landscape scales, to determine environmental factors that influence elk movement, and to evaluate movement and distribution patterns in relation to spatial and temporal aspects of the Cerro Grande Fire. Data collection and assimilation reflect the collaborative efforts of National Park Service, U.S. Forest Service, and Department of Energy (Los Alamos National Laboratory) personnel. Geographic positioning system (GPS) collars were used to track 54 elk over a period of 3+ years and locational data were incorporated into a multi-layered geographic information system (GIS) for analysis. Preliminary tests of GPS collar accuracy indicated a strong effect of 2D fixes on position acquisition rates (PARs) depending on time of day and season of year. Slope, aspect, elevation, and land cover type affected dilution of precision (DOP) values …

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This thesis describes a first measurement of the W Boson mass through the decay into a muon and a neutrino in Run 2 of the Tevatron. The W Bosons are produced in proton-antiproton collisions at a center of mass energy of 1.96 TeV. The data sample used for this analysis corresponds to 200 pb{sup -1} recorded by the upgraded Collider Detector at Fermilab. The most important quantity in this measurement is the momentum of the muon measured in a magnetic spectrometer which is calibrated using the two quarkonium resonances J/{Psi} and {Upsilon}(1S). Systematic uncertainties arise from the modeling of the recoil when the W Boson is produced, the momentum calibration, the modeling of W Boson production and decay dynamics and backgrounds. The result is: M{sub W} = 80408 {+-} 50(stat.) {+-} 57(syst.) MeV/c{sup 2}.

This thesis centers on the use of spectral modeling techniques on data from the Sloan Digital Sky Survey (SDSS) to gain new insights into current questions in galaxy evolution. The SDSS provides a large, uniform, high quality data set which can be exploited in a number of ways. One avenue pursued here is to use the large sample size to measure precisely the mean properties of galaxies of increasingly narrow parameter ranges. The other route taken is to look for rare objects which open up for exploration new areas in galaxy parameter space. The crux of this thesis is revisiting the classical Kennicutt method for inferring the stellar initial mass function (IMF) from the integrated light properties of galaxies. A large data set ({approx} 10{sup 5} galaxies) from the SDSS DR4 is combined with more in-depth modeling and quantitative statistical analysis to search for systematic IMF variations as a function of galaxy luminosity. Galaxy H{alpha} equivalent widths are compared to a broadband color index to constrain the IMF. It is found that for the sample as a whole the best fitting IMF power law slope above 0.5 M{sub {circle_dot}} is {Lambda} = 1.5 {+-} 0.1 with the error dominated by …

The measurement of the top-antitop pair production cross section in p{bar p} collisions at {radical}s = 1.96 TeV in the dielectron decay channel using 384 pb{sup -1} of D0 data yields a t{bar t} production cross-section of {sigma}{sub t{bar t}} = 7.9{sub -3.8}{sup +5.2}(stat){sub -1.0}{sup +1.3}(syst) {+-} 0.5 (lumi) pb. This measurement [98] is based on 5 observed events with a prediction of 1.04 background events. The cross-section corresponds to the top mass of 175 GeV, and is in good agreement with the Standard Model expectation of 6.77 {+-} 0.42 pb based on next-to-next-leading-order (NNLO) perturbative QCD calculations [78]. This analysis shows significant improvement from our previous cross-section measurement in this channel [93] with 230 pb{sup -1} dataset in terms of significantly better signal to background ratio and uncertainties on the measured cross-section. Combination of all the dilepton final states [98] yields a yields a t{bar t} cross-section of {sigma}{sub t{bar t}} = 8.6{sub -2.0}{sup +2.3}(stat){sub -1.0}{sup +1.2}(syst) {+-} 0.6(lumi) pb, which again is in good agreement with theoretical predictions and with measurements in other final states. Hence, these results show no discernible deviation from the Standard Model. Fig. 6.1 shows the summary of cross-section measurements in different final states …

This thesis presents evidence for the decay mode B{sup {+-}} {yields} {phi}K{sup {+-}} in p{bar p} collisions at {radical}s = 1.96 TeV using (120 {+-} 7)pb{sup -1} of data collected by the Collider Detector at Fermilab (CDF). This signal is then used to measure the branching ratio relative to the decay mode B{sup {+-}} {yields} J/{psi}K{sup {+-}}. The measurement starts from reconstructing the two decay modes: B{sup {+-}} {yields} {phi}K{sup {+-}}, where {phi} {yields} K{sup +}K{sup -} and B{sup {+-}} {yields} J/{psi}K{sup {+-}}, where J/{psi} {yields} {mu}{sup +}{mu}{sup -}. The measurement yielded 23 {+-} 7 B{sup {+-}} {yields} {phi}K{sup {+-}} events, and 406 {+-} 26 B{sup {+-}} {yields} J/{psi}K{sup {+-}} events. The fraction of B{sup {+-}} {yields} J/{psi}K{sup {+-}} events where the J/{psi} subsequently decayed to two muons (as opposed to two electrons) was found to be f{sub {mu}{mu}} = 0.839 {+-} 0.066. The relative branching ratio of the two decays is then calculated based on the equation: BR(B{sup {+-}} {yields} {phi}K{sup {+-}})/BR(B{sup {+-}} {yields} J/{psi}K{sup {+-}}) = N{sub {phi}K}/N{sub {psi}K} {center_dot}f{sub {mu}{mu}} BR(J/{psi} {yields} {mu}{sup +}{mu}{sup -})/BR({phi} {yields} K{sup +}K{sup -}) {epsilon}{sub {mu}{mu}}K/{epsilon}KKK R({epsilon}{sub iso}). The measurement finds BR(B{sup {+-}} {yields} {phi}K{sup {+-}})/BR(B{sup {+-}} {yields} J/{psi}K{sup {+-}}) = 0.0068 …

In this thesis we present a measurement of the relative fraction of t{bar t} events produced via gluon-fusion to the total number of t{bar t} events. Using the kinematics of the production and decay of the top and antitop quark pair, we trained a Neural Network to discriminate the gluon-fusion events. The Neural Network was then used as a template to fit for the gluon-fusion fraction in data. Using a total integrated luminosity of 955 pb{sup -1} we find {sigma}(gg{yields}t{bar t})/{sigma}(p{bar p}{yields}t{bar t}) < 0.33 at 68% confidence level and {sigma}(gg{yields}t{bar t})/{sigma}(p{bar p}{yields}t{bar t}) < 0.61 at 95% confidence level.

I present a measurement of the t{bar t} differential cross section, d{sigma}/dM{sub t{bar t}}, in p{bar p} collisions at {radical}s = 1.96 TeV using 2.7 fb{sup -1} of CDF II data. I find that d{sigma}/dM{sub t{bar t}} is consistent with the Standard Model expectation, as modeled by PYTHIA with CTEQ5L parton distribution functions. I set limits on the ratio {kappa}/M{sub Pl} in the Randall-Sundrum model by looking for Kaluza Klein gravitons which decay to top quarks. I find {kappa}/M{sub Pl} > 0.16 at the 95% confidence level.

The authors present a measurement of the {bar p}p {yields} W{gamma} + X {yields} e{nu}{gamma} + X production cross section using data form the Collider Detector at Fermilab. The p{bar p} collisions were provided by the Tevatron Collider at a center of mass energy of 1.96 TeV. Electroweak theory includes the trilinear vector boson coupling, WW{gamma}, which contributes to the e{nu}{gamma} final state. The electron decay channel of the W provides a clean sample to study the production of diboson pairs. The measurement of the production cross section tests the structure of the non-Abelian character of Electroweak theory.

In 1995 the last missing member of the known families of quarks, the top quark, was discovered by the CDF and D0 experiments at the Tevatron, a proton-antiproton collider at Fermilab near Chicago. Until today, the Tevatron is the only place where top quarks can be produced. The determination of top quark production and properties is crucial to understand the Standard Model of particle physics and beyond. The most striking property of the top quark is its mass--of the order of the mass of a gold atom and close to the electroweak scale--making the top quark not only interesting in itself but also as a window to new physics. Due to the high mass, much higher than of any other known fermion, it is expected that the top quark plays an important role in electroweak symmetry breaking, which is the most prominent candidate to explain the mass of particles. In the Standard Model, electroweak symmetry breaking is induced by one Higgs field, producing one additional physical particle, the Higgs boson. Although various searches have been performed, for example at the Large Electron Positron Collider (LEP), no evidence for the Higgs boson could yet be found in any experiment. At the …

Performance-driven interface contract enforcement research aims to improve the quality of programs built from plug-and-play scientific components. Interface contracts make the obligations on the caller and all implementations of the specified methods explicit. Runtime contract enforcement is a well-known technique for enhancing testing and debugging. However, checking all of the associated constraints during deployment is generally considered too costly from a performance stand point. Previous solutions enforced subsets of constraints without explicit consideration of their performance implications. Hence, this research measures the impacts of different interface contract sampling strategies and compares results with new techniques driven by execution time estimates. Results from three studies indicate automatically adjusting the level of checking based on performance constraints improves the likelihood of detecting contract violations under certain circumstances. Specifically, performance-driven enforcement is better suited to programs exercising constraints whose costs are at most moderately expensive relative to normal program execution.

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This dissertation reports the results of a search for charged Higgs bosons in the decays of t{bar t} pairs produced in p{bar p} collisions at a center-of-mass energy of 1.96 TeV. The search is performed on a data sample recorded by the upgraded Collider Detector at Fermilab and corresponding to an integrated luminosity of 193 pb{sup -1}. The search is based on the relative rates of events in the different t{bar t} decay channels. Results are obtained in the context of different models. In the context of the minimal supersymmetric extension of the Standard Model (MSSM), for which they fully account for radiative and Yukawa coupling corrections, regions in the (m{sub H{sup {+-}}}, tan ({beta})) plane are excluded. In the Tauonic Higgs Model in which the charged Higgs is assumed to decay exclusively to {bar {tau}}, the BR(t {yields} H{sup +}b) is constrained to be less than 0.4 at 95% C.L. If no assumption is made on the charged Higgs decay, the BR(t {yields} H{sup +}b) is constrained to be less than 0.90 at 95% C.L. No evidence for charged Higgs production is found.

We present a search for high-mass resonances decaying into two leptons of different flavor: e{mu}, e{tau}, and {mu}{tau}. These resonances are predicted by several models beyond the standard model, such as the R-parity-violating MSSM. The search is based on 1 fb{sup -1} of data collected at the Collider Detector at Fermilab (CDF II) in proton anti-proton collisions. Our observations are consistent with the standard model expectations. The results are interpreted to set 95% C.L. upper limits on {sigma} x BR of {tilde {nu}}{sub {tau}} {yields} e{mu}, e{tau}, {mu}{tau}.

We perform a search for {nu}{sub {mu}} {yields} {nu}{sub e} oscillations, a process which would manifest a nonzero value of the {theta}{sub 13} mixing angle, in the MINOS long-baseline neutrino oscillation experiment. The analysis consists of searching for an excess of {nu}{sub e} charged-current candidate events over the predicted backgrounds, made mostly of neutral-current events with high electromagnetic content. A novel technique to select electron neutrino events is developed, which achieves an improved separation between the signal and the backgrounds, and which consequently yields a better reach in {theta}{sub 13}. The backgrounds are predicted in the Far Detector from Near Detector measurements. An excess is observed in the Far Detector data over the predicted backgrounds, which is consistent with the background-only hypothesis at 1.2 standard deviations.

This dissertation describes a search for the associated production of the supersymmetric particles, the chargino and the neutralino, through their R-parity conserving decays to three leptons and missing energy. This search is carried out using the data collected at the CDF experiment at the Tevatron {radical}s = 1.96 TeV p{bar p} collider at Fermilab. The results are obtained by combining five independent channels with varying signal to background ratio. Overall, a total of 6.4 {+-} 1.1 background events from standard model processes and 11.4 {+-} 1.1 signal events for a particular choice of mSUGRA model parameters are expected. The observation of 7 events in data is consistent with the standard model background expectation, and the mSUGRA model is constrained. Limits are set on the cross section of Chargino-Neutralino pair production, and a limit on the mass of the chargino is extracted. A method of obtaining model-independent results is also discussed.

This dissertation describes a search for Z/{gamma}* boson pair production decaying into {mu}{mu}{mu}{mu}, {mu}{mu}ee, and eeee final states with approximately 1 fb{sup -1} of data at the Fermilab Tevatron Collider at {radical}s = 1.96 TeV. The small cross section times branching ratio for each channel mandated a thorough study of the acceptance and efficiencies. After optimization, 1.7 {+-} 0.1 events are expected for Standard Model production with a background of 0.13 {+-} 0.03 events. One event was found in the {mu}{mu}ee channel. A cross section limit of 4.4 pb is determined at a 95% confidence level for Standard Model production. Additionally, one parameter and two parameter 95% C.L. limits are found for the anomalous neutral trilinear gauge couplings ZZZ* and ZZ{gamma}*. The one parameter 95% C.L. coupling limits with a form factor scale of 1.2 TeV are: -0.28 < f{sub 40}{sup Z} < 0.28, -0.31 < f{sub 50}{sup Z} < 0.29, -0.26 < f{sub 40}{gamma} < 0.26, and -0.30 < f{sub 50}{sup {gamma}} < 0.28.