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Fabrication and characterization of submicron polymer waveguides by micro-transfer molding

Description: Various methods exist for fabrication of micron and submicron sized waveguide structures. However, most of them include expensive and time consuming semiconductor fabrication techniques. An economical method for fabricating waveguide structures is introduced and demonstrated in this thesis. This method is established based on previously well-developed photonic crystal fabrication method called two-polymer microtransfer molding. The waveguide in this work functions by a coupler structure that diffracts the incident light into submicron polymer rods. The light is then guided through the rods. Characterization is done by collecting the light that has been guided through the waveguide and exits the end of these submicron polymer bars. The coupling and waveguiding capabilities are demonstrated using two light sources, a laser and white light.
Date: December 15, 2009
Creator: Wu, Te-Wei
Partner: UNT Libraries Government Documents Department

CROSS SECTION MEASUREMENTS IN THE MAIN INJECTOR PARTICLE PRODUCTION (FNAL-E907) EXPERIMENT AT 58 GEV ENERGY

Description: Cross-sections are presented for 58 GeV {pi}, K, and p on a wide range of nuclear targets. These cross-sections are essential for determining the neutrino flux in measurements of neutrino cross-sections and oscillations. The E907 Main Injector Particle Production (MIPP) experiment at Fermilab is a fixed target experiment for measuring hadronic particle production using primary 120 GeV/c protons and secondary {pi}, K, and p beams. The particle identification is made by dE/dx in a time projection chamber, and by time-of-flight, differential Cherenkov and ring imaging Cherenkov detectors, which together cover a wide range of momentum from 0.1 GeV/c up to 120 GeV/c. MIPP targets span the periodic table, from hydrogen to uranium, including beryllium and carbon. The MIPP has collected {approx} 0.26 x 10{sup 6} events of 58 GeV/c secondary particles produced by protons from the main injector striking a carbon target.
Date: December 1, 2009
Creator: Gunaydin, Yusuf Oguzhan & U., /Iowa
Partner: UNT Libraries Government Documents Department

Observation of Electroweak Single Top-Quark Production with the CDF II Experiment

Description: The standard model of elementary particle physics (SM) predicts, besides the top-quark pair production via the strong interaction, also the electroweak production of single top-quarks [19]. Up to now, the Fermilab Tevatron proton-antiproton-collider is the only place to produce and study top quarks emerging from hadron-hadron-collisions. Top quarks were directly observed in 1995 during the Tevatron Run I at a center-of-mass energy of {radical}s = 1.8 TeV simultaneously by the CDF and D0 Collaborations via the strong production of top-quark pairs. Run II of the Tevatron data taking period started 2001 at {radical}s = 1.96 TeV after a five year upgrade of the Tevatron accelerator complex and of both experiments. One main component of its physics program is the determination of the properties of the top quark including its electroweak production. Even though Run II is still ongoing, the study of the top quark is already a successful endeavor, confirmed by dozens of publications from both Tevatron experiments. A comprehensive review of top-quark physics can be found in reference. The reasons for searching for single top-quark production are compelling. As the electroweak top-quark production proceeds via a Wtb vertex, it provides the unique opportunity of the direct measurement of the CKM matrix element |V{sub tb}|, which is expected to be |V{sub tb}| {approx} 1 in the SM. Significant deviations from unity could be an indication of a fourth quark generation, a production mode via flavor-changing neutral currents, and other new phenomena, respectively. There are two dominating electroweak top-quark production modes at the Fermilab Tevatron: the t-channel exchange of a virtual W boson striking a b quark and the s-channel production of a timelike W boson via the fusion of two quarks. In proton-antiproton-collisions the third electroweak production mode, the associated Wt production of an on-shell W boson in conjunction with ...
Date: July 1, 2009
Creator: Lueck, Jan & /KARLSRUHE U., EKP
Partner: UNT Libraries Government Documents Department

IMPROVING THE PHYSICS IMPACT OF NEXT-GENERATION 76GE NEUTRINOLESS DOUBLE-BETA DECAY EXPERIMENTS

Description: Summary and Conclusions - It was shown that segmentation and pulse-shape discrimination can improve the discovery sensitivity of a next-gen 0vBB-decay experiment by 90%. - However, when practical aspects are considered (such as instrumenting each segment with front-end electronics), the discovery sensitivity is decreased by 19%. - This has extremely important consequences to proposed next-gen experiments since the two active collaborations have strongly advocated the use of segmented detectors for all or part of the experiment. - New germanium detector technology, currently under development, has demonstrated excellent multi-site background rejection capabilities without the complexity of segmentation or complicated PSD algorithms. - The physically-segmented p-type germanium detector technology has proven to be a useful and practical tool in modern nuclear physics. The PSEG technology deserves further development as it has the potential for use in a variety of applications.
Date: June 2009
Creator: Hossbach, Todd W.
Partner: UNT Libraries Government Documents Department

First evidence for WW and WZ diboson production with semi-leptonic decays at a Hadron Collider

Description: Presented is a measurement of the simultaneous production of a W{sup {+-}} boson in association with a second weak boson (W{sup {+-}} or Z{sup 0}) in p{bar p} collisions at {radical}s = 1.96 TeV. Events are consider with one electron or one muon, missing transverse energy, and at least two hadronic jets. The data were collected by the D0 detector in Run IIa of the Tevatron accelerator and correspond to 1.07 fb{sup -1} of integrated luminosity for each of the two channels (WW/WZ {yields} e{nu}q{bar q} and WW/WZ {yields} {mu}{nu}q{bar q}). The cross section for WW + WZ production is measured to be 20.2 {+-} 2.5(stat) {+-} 3.6(sys) {+-} 1.2(lum) pb with a Gaussian significance of 4.4 standard deviations above the background-only scenario. This measurement is consistent with the Standard Model prediction and represents the first direct evidence for WW and WZ production with semi-leptonic decays at a hadron collider.
Date: March 1, 2009
Creator: Haley, Joseph Glenn Biddle & U., /Princeton
Partner: UNT Libraries Government Documents Department

Di-J/psi Studies, Level 3 Tracking and the D0 Run IIb Upgrade

Description: 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 0, has led to improvements in vertex resolution of {approx}4.5 {micro}m. A previous search in the di-J/{psi} channel revealed a unpredicted resonance at {approx}13.7 GeV/c{sup 2}. A confirmation analysis is presented using 2.8 fb{sup -1} of data and two different approaches to cuts. No significant excess is seen in the di-J/{psi} mass spectrum.
Date: October 1, 2009
Creator: Vint, Philip John & /Imperial Coll., London
Partner: UNT Libraries Government Documents Department

GAiN: Distributed Array Computation with Python

Description: Scientific computing makes use of very large, multidimensional numerical arrays - typically, gigabytes to terabytes in size - much larger than can fit on even the largest single compute node. Such arrays must be distributed across a "cluster" of nodes. Global Arrays is a cluster-based software system from Battelle Pacific Northwest National Laboratory that enables an efficient, portable, and parallel shared-memory programming interface to manipulate these arrays. Written in and for the C and FORTRAN programming languages, it takes advantage of high-performance cluster interconnections to allow any node in the cluster to access data on any other node very rapidly. The "numpy" module is the de facto standard for numerical calculation in the Python programming language, a language whose use is growing rapidly in the scientific and engineering communities. numpy provides a powerful N-dimensional array class as well as other scientific computing capabilities. However, like the majority of the core Python modules, numpy is inherently serial. Our system, GAiN (Global Arrays in NumPy), is a parallel extension to Python that accesses Global Arrays through numpy. This allows parallel processing and/or larger problem sizes to be harnessed almost transparently within new or existing numpy programs.
Date: April 24, 2009
Creator: Daily, Jeffrey A.
Partner: UNT Libraries Government Documents Department

From ZZ to ZH : How Low Can These Cross Sections Go or Everybody, Let's Cross Section Limbo!

Description: We report on two searches performed at the D0 detector at the Fermi National Laboratory. The first is a search for Z di-boson production with a theoretical cross section of 1.4 pb. The search was performed on 2.6 fb{sup -1} of data and contributed to the first observation of ZZ production at a hadron collider. The second is a search for a low mass Standard Model Higgs in 4.2 fb{sup -1} of data. The Higgs boson is produced in association with a Z boson where the Higgs decays hadronically and the Z decays to two leptons. The ZZ search was performed in both the di-electron and di-muon channels. For the ZH search, we will focus on the muonic decays where we expanded the traditional coverage by considering events in which one of the two muons fails the selection requirement, and is instead reconstructed as an isolated track. We consider Higgs masses between 100 and 150 GeV, with theoretical cross sections ranging from 0.17 to 0.042 pb, and set upper limits on the ZH production cross-section at 95% confidence level.
Date: August 1, 2009
Creator: Strauss, Emanuel Alexandre & /SUNY, Stony Brook
Partner: UNT Libraries Government Documents Department

Measurement of Differential Cross-Sections in the ttbar -> l+jets Channel

Description: The analysis presented in this thesis focuses on kinematic distributions in the t{bar t} system and studies in detail selected differential cross sections of top quarks as well as the reconstructed t{bar t} pair, namely the top quark transverse momentum and the t{bar t} system mass. The structure of the thesis is organized as follows: first the Standard Model of the particle physics is briefly introduced in Chapter 1, with relevant aspects of electroweak and strong interactions discussed. The physics of the top quark and its properties are then outlined in Chapter 2, together with the motivation for measuring the transverse top quark momentum and other kinematic-related variables of the t{bar t} system. The concepts of present-day high energy physics collider experiments and the explicit example of Fermilab Tevatron collider and the D0 detector in Chapters 3 and 4 are followed by the description of basic detector-level objects, i.e. tracks, leptons and jets, in Chapter 5; their identification and calibration following in next chapter with the emphasis on the jet energy scale in Chapter 6 and jet identification at the D0. The analysis itself is outlined in Chapter 7 and is structured so that first the data and simulation samples and the basic preselection are described in Chapter 8 and 9, followed by the kinematic reconstruction part in Chapter 10. Chapter 11 on background normalization and Chapter 12 with raw reconstructed spectra results (at the detector-smeared level) are followed by the purity-based background subtraction method and examples of signal-level corrected spectra in Chapter 13. Next, the procedure of correcting measured spectra for detector effects (unfolding) is described in Chapters 14-15, including migration matrix studies, acceptance correction determination as well as the regularized unfolding procedure itself. Final differential cross sections are presented in Chapter 16 with the main results in Figures ...
Date: April 1, 2009
Creator: Kvita, J. & U., /Charles
Partner: UNT Libraries Government Documents Department

Measurement of Neutrino-Nucleon Neutral-Current Elastic Scattering Cross-section at SciBooNE

Description: In this thesis, results of neutrino-nucleon neutral current (NC) elastic scattering analysis are presented. Neutrinos interact with other particles only with weak force. Measurement of cross-section for neutrino-nucleon reactions at various neutrino energy are important for the study of nucleon structure. It also provides data to be used for beam flux monitor in neutrino oscillation experiments. The cross-section for neutrino-nucleon NC elastic scattering contains the axial vector form factor G{sub A}(Q{sup 2}) as well as electromagnetic form factors unlike electromagnetic interaction. G{sub A} is propotional to strange part of nucleon spin ({Delta}s) in Q{sup 2} {yields} 0 limit. Measurement of NC elastic cross-section with smaller Q{sup 2} enables us to access {Delta}s. NC elastic cross-sections of neutrino-nucleon and antineutrino-nucleon were measured earlier by E734 experiment at Brookheaven National Laboratory (BNL) in 1987. In this experiment, cross-sections were measured in Q{sup 2} > 0.4 GeV{sup 2} region. Result from this experiment was the only published data for NC elastic scattering cross-section published before our experiment. SciBooNE is an experiment for the measurement of neutrino-nucleon scattering cross-secitons using Booster Neutrino Beam (BNB) at FNAL. BNB has energy peak at 0.7 GeV. In this energy region, NC elastic scattering, charged current elastic scattering, charged current pion production, and neutral current pion production are the major reaction branches. SciBar, electromagnetic calorimeter, and Muon Range Detector are the detectors for SciBooNE. The SciBar consists of finely segmented scintillators and 14336 channels of PMTs. It has a capability to reconstruct particle track longer than 8 cm and separate proton from muons and pions using energy deposit information. Signal of NC elastic scattering is a single proton track. In {nu}p {yields} {nu}p process, the recoil proton is detected. On the other hand, most of {nu}n {yields} {nu}n is invisible because there are only neutral particles in final ...
Date: February 1, 2009
Creator: Takei, Hideyuki & Tech., /Tokyo Inst.
Partner: UNT Libraries Government Documents Department

Measurement of the inclusive isolated prompt photon production cross section at the Tevatron using the CDF detector

Description: In this thesis we present the measurement of the inclusive isolated prompt photon cross section with a total integrated luminosity of 2.5 fb{sup -1} of data collected with the CDF Run II detector at the Fermilab Tevatron Collider. The prompt photon cross section is a classic measurement to test perturbative QCD (pQCD) with potential to provide information on the parton distribution function (PDF), and sensitive to the presence of new physics at large photon transverse momentum. Prompt photons also constitute an irreducible background for important searches such as H {yields} {gamma}{gamma}, or SUSY and extra-dimensions with energetic photons in the final state. The Tevatron at Fermilab (Batavia, U.S.A.) is currently the hadron collider that operates at the highest energies in the world. It collides protons and antiprotons with a center-of-mass energy of 1.96 TeV. The CDF and the D0 experiments are located in two of its four interaction regions. In Run I at the Tevatron, the direct photon production cross section was measured by both CDF and DO, and first results in Run II have been presented by the DO Collaboration based on 380 pb{sup -1}. Both Run I and Run II results show agreement with the theoretical predictions except for the low p{sub T}{sup {gamma}} region, where the observed and predicted shapes are different. Prompt photon production has been also extensively measured at fixed-target experiments in lower p{sub T}{sup {gamma}} ranges, showing excess of data compared to the theory, particularly at high x{sub T}. From an experimental point of view, the study of the direct photon production has several advantages compared to QCD studies using jets. Electromagnetic calorimeters have better energy resolution than hadronic calorimeters, and the systematic uncertainty on the photon absolute energy scale is smaller. Furthermore, the determination of the photon kinematics does not require the use ...
Date: April 1, 2009
Creator: Deluca Silberberg, Carolina & /Barcelona, IFAE
Partner: UNT Libraries Government Documents Department

Measurement of the top quark pair production cross section in proton-antiproton collisions at a center of mass energy of 1.96 TeV, hadronic top decays with the D0 detector

Description: Of the six quarks in the standard model the top quark is by far the heaviest: 35 times more massive than its partner the bottom quark and more than 130 times heavier than the average of the other five quarks. Its correspondingly small decay width means it tends to decay before forming a bound state. Of all quarks, therefore, the top is the least affected by quark confinement, behaving almost as a free quark. Its large mass also makes the top quark a key player in the realm of the postulated Higgs boson, whose coupling strengths to particles are proportional to their masses. Precision measurements of particle masses for e.g. the top quark and the W boson can hereby provide indirect constraints on the Higgs boson mass. Since in the standard model top quarks couple almost exclusively to bottom quarks (t {yields} Wb), top quark decays provide a window on the standard model through the direct measurement of the Cabibbo-Kobayashi-Maskawa quark mixing matrix element V{sub tb}. In the same way any lack of top quark decays into W bosons could imply the existence of decay channels beyond the standard model, for example charged Higgs bosons as expected in two-doublet Higgs models: t {yields} H{sup +}b. Within the standard model top quark decays can be classified by the (lepton or quark) W boson decay products. Depending on the decay of each of the W bosons, t{bar t} pair decays can involve either no leptons at all, or one or two isolated leptons from direct W {yields} e{bar {nu}}{sub e} and W {yields} {mu}{bar {nu}}{sub {mu}} decays. Cascade decays like b {yields} Wc {yields} e{bar {nu}}{sub e}c can lead to additional non-isolated leptons. The fully hadronic decay channel, in which both Ws decay into a quark-antiquark pair, has the largest branching fraction ...
Date: January 16, 2009
Creator: Hegeman, Jeroen Guido & /Twente U. Tech., Enschede
Partner: UNT Libraries Government Documents Department

MINOS Sterile Neutrino Search

Description: The Main Injector Neutrino Oscillation Search (MINOS) is a long-baseline accelerator neutrino experiment designed to measure properties of neutrino oscillation. Using a high intensity muon neutrino beam, produced by the Neutrinos at Main Injector (NuMI) complex at Fermilab, MINOS makes two measurements of neutrino interactions. The first measurement is made using the Near Detector situated at Fermilab and the second is made using the Far Detector located in the Soudan Underground laboratory in northern Minnesota. The primary goal of MINOS is to verify, and measure the properties of, neutrino oscillation between the two detectors using the {nu}{sub {mu}} {yields} V{sub {tau}} transition. A complementary measurement can be made to search for the existence of sterile neutrinos; an oft theorized, but experimentally unvalidated particle. The following thesis will show the results of a sterile neutrino search using MINOS RunI and RunII data totaling {approx}2.5 x 10{sup 20} protons on target. Due to the theoretical nature of sterile neutrinos, complete formalism that covers transition probabilities for the three known active states with the addition of a sterile state is also presented.
Date: September 1, 2009
Creator: Koskinen, David Jason & London, /University Coll.
Partner: UNT Libraries Government Documents Department

Measurement of the branching fraction Bs->Ds(*)Ds(*) using the D0 detector at Fermilab

Description: This thesis describes a measurement of the branching fraction Br(B{sup 0}{sub s} {yields} D{sup (*)}{sub s} D{sup (*)}{sub s}) made using a data sample collected from proton-antiproton collisions at a centre-of-mass energy of 1.96 TeV, corresponding to approximately 1.3 fb{sup -1} of integrated luminosity collected in 2002--2006 by the D0 detector at the Fermilab Tevatron Collider. One D{sup (*)}{sub s} meson was partially reconstructed in the decay D{sub s} {yields} {phi}{mu}{nu}, and the other D{sup (*)}{sub s} meson was identified using the decay D{sub s} {yields} {phi}{pi} where no attempt was made to distinguish D{sub s} and D{sup *}{sub s} states. The resulting measurement is Br(B{sup 0}{sub s} {yields} D{sup (*)}{sub s} D{sup (*)}{sub s}) = 0.039{sup +0.019}{sub -0.017}(stat){sup +0.016}{sub -0.015}(syst). This was subsequently used to estimate the width difference {Delta}{Gamma}{sup CP}{sub s} in the B{sup 0}{sub s}-{anti B}{sup 0}{sub s} system: {Delta}{Gamma}{sup CP}{sub s}/{Gamma}{sub s} = 0.079{sup +0.038}{sub -0.035}(stat){sup +0.031}{sub 0.030}(syst), and is currently one of the most precise estimates of this quantity and consistent with the Standard Model.
Date: February 1, 2009
Creator: Walder, James William & U., /Lancaster
Partner: UNT Libraries Government Documents Department

Measurements of Time-Dependent CP-Asymmetry Parameters in B Meson Decays to \eta^{\prime} K^0 and of Branching Fractions of SU(3) Related Modes with BaBar Experiment at SLAC

Description: In this thesis work we have measured the following upper limits at 90% of confidence level, for B meson decays (in units of 10{sup -6}), using a statistics of 465.0 x 10{sup 6} B{bar B} pairs: {Beta}(B{sup 0} {yields} {eta}K{sup 0}) < 1.6 {Beta}(B{sup 0} {yields} {eta}{eta}) < 1.4 {Beta}(B{sup 0} {yields} {eta}{prime}{eta}{prime}) < 2.1 {Beta}(B{sup 0} {yields} {eta}{phi}) < 0.52 {Beta}(B{sup 0} {yields} {eta}{omega}) < 1.6 {Beta}(B{sup 0} {yields} {eta}{prime}{phi}) < 1.2 {Beta}(B{sup 0} {yields} {eta}{prime}{omega}) < 1.7 We have no observation of any decay mode, statistical significance for our measurements is in the range 1.3-3.5 standard deviation. We have a 3.5{sigma} evidence for B {yields} {eta}{omega} and a 3.1 {sigma} evidence for B {yields} {eta}{prime}{omega}. The absence of observation of the B{sup 0} {yields} {eta}K{sup 0} open an issue related to the large difference compared to the charged mode B{sup +} {yields} {eta}K{sup +} branching fraction, which is measured to be 3.7 {+-} 0.4 {+-} 0.1 [118]. Our results represent substantial improvements of the previous ones [109, 110, 111] and are consistent with theoretical predictions. All these results were presented at Flavor Physics and CP Violation (FPCP) 2008 Conference, that took place in Taipei, Taiwan. They will be soon included into a paper to be submitted to Physical Review D. For time-dependent analysis, we have reconstructed 1820 {+-} 48 flavor-tagged B{sup 0} {yields} {eta}{prime}K{sup 0} events, using the final BABAR statistic of 467.4 x 10{sup 6} B{bar B} pairs. We use these events to measure the time-dependent asymmetry parameters S and C. We find S = 0.59 {+-} 0.08 {+-} 0.02, and C = -0.06 {+-} 0.06 {+-} 0.02. A non-zero value of C would represent a directly CP non-conserving component in B{sup 0} {yields} {eta}{prime}K{sup 0}, while S would be equal to sin2{beta} measured in B{sup 0} ...
Date: January 22, 2009
Creator: Biassoni, Pietro & U., /Milan
Partner: UNT Libraries Government Documents Department

Measurements of top quark pair production cross section in proton anti-proton collisions at s**(1/2) = 1.96 TeV in the tau + jets final state using 1 inv fb of data

Description: This dissertation presents a new measurement of p{bar p} {yields} t{bar t}X production at {radical}s = 1.96 TeV using 974.2 pb{sup -1} of data collected with the D0 detector between 2002 and 2006. We focus on the final state where the W boson from one of the top quarks decays into a {tau} lepton and its associated neutrino, while the other W boson decays into a quark-antiquark pair. We aim to select those events in which the {tau} lepton subsequently decays hadronically, meaning to one or three charged hadrons, zero or more neutral hadrons and a tau neutrino (the charge conjugate processes are implied in all of the above). The observable signature thus consists of a narrow calorimeter shower with associated track(s) characteristic of a hadronic tau decay, four or more jets, of which two are initiated by b quarks accompanying the W's in the top quark decays, and a large net missing momentum in the transverse plane due to the energetic neutrino-antineutrino pair that leave no trace in the detector media. The preliminary result for the measured cross section is: {sigma}(t{bar t}) = 6.9{sub -1.2}{sup +1.2}(stat){sub -0.7}{sup +0.8}(syst) {+-} 0.4 (lumi) pb. This indicates that our finding is consistent with the Standard Model prediction.
Date: December 1, 2009
Creator: Hossain, Sohrab & U., /Oklahoma
Partner: UNT Libraries Government Documents Department

Measurement of the W boson mass and width using a novel recoil model

Description: This dissertation presents a direct measurement of the W boson mass (M{sub W}) and decay width ({Lambda}{sub W}) in 1 fb{sup -1} of W {yields} e{nu} collider data at D0 using a novel method to model the hadronic recoil. The mass is extracted from fits to the transverse mass M{sub T}, p{sub T}(e), and E{sub T} distributions. The width is extracted from fits to the tail of the M{sub T} distribution. The electron energy measurement is simulated using a parameterized model, and the recoil is modeled using a new technique by which Z recoils are chosen from a data library to match the p{sub T} and direction of each generated W boson. We measure the the W boson mass to be M{sub W} = 80.4035 {+-} 0.024(stat) {+-} 0.039(syst) from the M{sub T}, M{sub W} = 80.4165 {+-} 0.027(stat) {+-} 0.038(syst) from the pT(e), and MW = 80.4025 {+-} 0.023(stat) {+-} 0.043(syst) from the E{sub T} distributions. {Lambda}{sub W} is measured to be {Lambda}{sub W} = 2.025 {+-} 0.038(stat) {+-} 0.061(syst) GeV.
Date: January 1, 2009
Creator: Wetstein, Matthew J. & U., /Maryland
Partner: UNT Libraries Government Documents Department

Measurements of the Differential Cross Sections for the Inclusive Production of a Photon and Heavy Flavor Jet

Description: This thesis presents the first measurement of the differential production cross section of a heavy flavor (bottom or charm) jet and direct photon at the Fermilab Tevatron. These measurements were performed using data recorded with the D0 detector from proton-antiproton collisions at a center of mass energy of {radical}s = 1.96 TeV. These results probe a kinematic range for the photon transverse momentum of 30 < p{sub T}{sup {gamma}} < 150 GeV and rapidity of |y{sup {gamma}}| < 1.0 and for jet transverse momentum p{sub T}{sup jet} > 15 GeV and rapidity of |y{sup jet}| < 0.8. These results are compared to next-to-leading-order theoretical calculations.
Date: April 1, 2009
Creator: Duggan, Daniel & U., /Florida State
Partner: UNT Libraries Government Documents Department

SAMPLING AND MASS SPECTROMETRY APPROACHES FOR THE DETECTION OF DRUGS AND FOREIGN CONTAMINANTS IN BREATH FOR HOMELAND SECURITY APPLICATIONS

Description: Homeland security relies heavily on analytical chemistry to identify suspicious materials and persons. Traditionally this role has focused on attribution, determining the type and origin of an explosive, for example. But as technology advances, analytical chemistry can and will play an important role in the prevention and preemption of terrorist attacks. More sensitive and selective detection techniques can allow suspicious materials and persons to be identified even before a final destructive product is made. The work presented herein focuses on the use of commercial and novel detection techniques for application to the prevention of terrorist activities. Although drugs are not commonly thought of when discussing terrorism, narcoterrorism has become a significant threat in the 21st century. The role of the drug trade in the funding of terrorist groups is prevalent; thus, reducing the trafficking of illegal drugs can play a role in the prevention of terrorism by cutting off much needed funding. To do so, sensitive, specific, and robust analytical equipment is needed to quickly identify a suspected drug sample no matter what matrix it is in. Single Particle Aerosol Mass Spectrometry (SPAMS) is a novel technique that has previously been applied to biological and chemical detection. The current work applies SPAMS to drug analysis, identifying the active ingredients in single component, multi-component, and multi-tablet drug samples in a relatively non-destructive manner. In order to do so, a sampling apparatus was created to allow particle generation from drug tablets with on-line introduction to the SPAMS instrument. Rules trees were developed to automate the identification of drug samples on a single particle basis. A novel analytical scheme was also developed to identify suspect individuals based on chemical signatures in human breath. Human breath was sampled using an RTube{trademark} and the trace volatile organic compounds (VOCs) were preconcentrated using solid phase microextraction ...
Date: January 27, 2009
Creator: Martin, A N
Partner: UNT Libraries Government Documents Department

Search for the Higgs boson produced in association with a W boson at CDF Run II

Description: We present a search for standard model Higgs boson production in association with a W boson in proton-antiproton collisions (p{bar p} {yields} W{sup {+-}}H {yields} {ell}{nu}b{bar b}) at a center of mass energy of 1.96 TeV. WH candidate events have a signature of a single lepton (E{sup {+-}}/{mu}{sup {+-}}), missing transverse energy, and two jets. The search looks for candidate events in approximately 2.7 fb{sup -1} of data recorded with the CDF II detector. The high-p{sub T} lepton (e,{mu}) in the events provides a distinct signature for triggering and most of the events in the dataset come from high-p{sub t} lepton triggers. Our analysis improves on prior searches by including events recorded on the E{sub T} + 2 Jets trigger with a lepton reconstructed as an isolated high-p{sub T} charged particle. We increase the sample purity by identifying ('tagging') long-lived b-hadrons in jets. A neural network combines distinguishing kinematic information into a function optimized for WH sensitivity. The neural network output distributions are consistent with the standard model background expectations and we set limits upper limits on the rate of Higgs production. We set 95% confidence level upper limits on the WH production cross section times branching ratio for Higgs masses from 100 to 150 GeV/c{sup 2} and express our results as a ratio of the experimental limit to the theoretical Standard Model production rate. Our limits range from 3.6 (4.3 expected) to 61.1 (43.2 expected) for Higgs masses from 100 to 150 GeV/c{sup 2}, respectively.
Date: January 1, 2009
Creator: Slaunwhite, Jason Michael & U., /Ohio State
Partner: UNT Libraries Government Documents Department

Neutrino-nucleus neutral current elastic interactions measurement in MiniBooNE

Description: The MiniBooNE experiment at the Fermi National Accelerator Laboratory (Fermilab) was designed to search for {nu}{sub {mu}} {yields} {nu}{sub e} neutrino oscillations at {Delta}m{sup 2} {approx} 1 eV{sup 2} using an intense neutrino flux with an average energy E{sub {nu}} {approx} 700 MeV. From 2002 to 2009 MiniBooNE has accumulated more than 1.0 x 10{sup 21} protons on target (POT) in both neutrino and antineutrino modes. MiniBooNE provides a perfect platform for detailed measurements of exclusive and semiinclusive neutrino cross-sections, for which MiniBooNE has the largest samples of events up to date, such as neutral current elastic (NCE), neutral current {pi}{sup 0}, charged current quasi-elastic (CCQE), charged current {pi}{sup +}, and other channels. These measured cross-sections, in turn, allow to improve the knowledge of nucleon structure. This thesis is devoted to the study of NCE interactions. Neutrino-nucleus neutral current elastic scattering ({nu}N {yields} {nu}N) accounts for about 18% of all neutrino interactions in MiniBooNE. Using a high-statistics, high purity sample of NCE interactions in MiniBooNE, the flux-averaged NCE differential cross-section has been measured and is being reported here. Further study of the NCE cross-section allowed for probing the structure of nuclei. The main interest in the NCE cross-section is that it may be sensitive to the strange quark contribution to the nucleon spin, {Delta}s, this however requires a separation of NCE proton ({nu}p {yields} {nu}p) from NCE neutron ({nu}n {yields} {nu}n) events, which in general is a challenging task. MiniBooNE uses a Cherenkov detector, which imposes restrictions on the measured nucleon kinematic variables, mainly due to the impossibility to reconstruct the nucleon direction below the Cherenkov threshold. However, at kinetic energies above this threshold MiniBooNE is able to identify NCE proton events that do not experience final state interactions (FSI). These events were used for the {Delta}s measurement. In this ...
Date: December 1, 2009
Creator: Perevalov, Denis & U., /Alabama
Partner: UNT Libraries Government Documents Department

Radiative B Meson Decay as a Probe of Physics Beyond the Standard Model: Time-Dependent CP Violation in B0 --> KS pi0 gamma and the B --> phi K gamma Branching Fraction

Description: The author presents measurements of radiative B meson decays to the final states K{sub s}{sup 0}{pi}{sup 0}{gamma} and K{phi}{gamma} based on data collected at the {Upsilon}(4S) resonance with the BABAR detector at the PEP-II e{sup +}e{sup -} collider at SLAC. In a data sample of 467 million B{bar B} pairs, the time-dependent CP asymmetry in B{sup 0} {yields} K{sub s}{sup 0}{pi}{sup 0}{gamma} decays is measured in two regions of K{sub s}{sup 0}-{pi}{sup 0} invariant mass. In the K* region, 0.8 < m(K{sub s}{sup 0}{pi}{sup 0}) < 1.0 GeV/c{sup 2}, we find S{sub K*{gamma}} = -0.03 {+-} 0.29 {+-} 0.03 and C{sub K*{gamma}} = -0.14 {+-} 0.16 {+-} 0.03; in the range 1.1 < m(K{sub s}{sup 0}{pi}{sup 0}) < 1.8 GeV/c{sup 2}, they find S{sub K{sub s}{sup 0}{pi}{sup 0}{gamma}} = -0.78 {+-} 0.59 {+-} 0.09 and C{sub K{sub s}{sup 0}{pi}{sup 0}{gamma}} = -0.36 {+-} 0.33 {+-} 0.04. With a sample of 228 million B{bar B} pairs they measure the branching fraction {Beta}(B{sup +} {yields} K{sup +}{phi}{gamma}) = (3.5 {+-} 0.6 {+-} 0.4) x 10{sup -6} and set the limit {Beta}(B{sup 0} {yields} K{sup 0}{phi}{gamma}) < 2.7 x 10{sup -6} at 90% confidence level. The direct CP asymmetry in B{sup +} {yields} K{sup +}{phi}{gamma} is found to be A{sub CP} = (-26 {+-} 14 {+-} 5)%. In each case the uncertainties are statistical and systematic, respectively.
Date: January 22, 2009
Creator: Tuggle, Joseph Marion, IV & U., /Maryland
Partner: UNT Libraries Government Documents Department

A search for muon neutrino and antineutrino disappearance in the Booster Neutrino Beam

Description: This dissertation presents a search for {mu}{sub {nu}} and {bar {mu}{sub {nu}}} disappearance with the MiniBooNE experiment in the {Delta}m{sup 2} region of a few eV{sup 2}. Disappearance measurements in this oscillation region constrain sterile neutrino models and CPT violation in the lepton sector. Fits to the shape of the {mu}{sub {nu}} and {bar {mu}{sub {nu}}} energy spectra reveal no evidence for disappearance in either mode. This is the first test of {bar {mu}{sub {nu}}} disappearance between {Delta}m{sup 2} = 0:1 -- 10 eV2. In addition, prospects for performing a joint analysis using the SciBooNE detector in conjunction with MiniBooNE are discussed.
Date: April 1, 2009
Creator: Mahn, Kendall Brianna McConnel & U., /Columbia
Partner: UNT Libraries Government Documents Department

A search for muon neutrino to electron neutrino oscillations in the MINOS Experiment

Description: 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.
Date: October 1, 2009
Creator: Ochoa Ricoux, Juan Pedro & /Caltech
Partner: UNT Libraries Government Documents Department