This Thesis presents measurements of the decays B{sup -} {yields} {Xi}{sub c}{sup 0}{bar {Lambda}}{sub c}{sup -}, {bar B}{sup 0} {yields} {Xi}{sub c}{sup +}{bar {Lambda}}{sub c}{sup -}, B{sup -} {yields} {Lambda}{sub c}{sup +}{bar {Lambda}}{sub c}{sup -} K{sup -}, and {bar B}{sup 0} {yields} {Lambda}{sub c}{sup +}{bar {Lambda}}{sub c}{sup -} K{sub s}{sup 0} based on 228 million {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the SLAC PEP-II asymmetric-energy B factory.

One of the central questions arising from human curiosity has always been what matter is ultimately made of, with the idea of some kind of elementary building-block dating back to the ancient greek philosophers. Scientific activities of multiple generations have contributed to the current best knowledge about this question, the Standard Model of particle physics. According to it, the world around us is composed of a small number of stable elementary particles: Electrons and two different kinds of quarks, called up and down quarks. Quarks are never observed as free particles, but only as bound states of a quark-antiquark pair (mesons) or of three quarks (baryons), summarized as hadrons. Protons and Neutrons, the constituents forming the nuclei of all chemical elements, are baryons made of up and down quarks. The electron and the electron neutrino - a nearly massless particle without electric charge - belong to a group called leptons. These two quarks and two leptons represent the first generation of elementary particles. There are two other generations of particles, which seem to have similar properties as the first generation except for higher masses, so there are six quarks and six leptons altogether. They were around in large amounts shortly …

In this paper I argue for the need for a strong Science and Technology program in the Nuclear Weapons Complex as the basis for maintaining a credible deterrence capability. The current Nuclear Posture Review establishes a New Triad as the basis for the United States deterrence strategy in a changing security environment. A predictive science capability is at the core of a credible National Nuclear Weapons program in the 21st Century. In absence of nuclear testing, the certification of our current Nuclear Weapons relies on predictive simulations and quantification of the associated simulation uncertainties. In addition, a robust nuclear infrastructure needs an active research and development program that considers all the required nuclear scenarios, including new configurations for which there is no nuclear test data. This paper also considers alternative positions to the need for a Science and Technology program in the Nuclear Weapons complex.

This dissertation focuses on the development of facile and rapid quantitative Raman spectroscopy measurements for the determination of conversion products in producing bioethanol from corn stover. Raman spectroscopy was chosen to determine glucose, xylose and ethanol in complex hydrolysis and fermentation matrices. Chapter 1 describes the motives and main goals of this work, and includes an introduction to biomass, commonly used pretreatment methods, hydrolysis and fermentation reactions. The principles of Raman spectroscopy, its advantages and applications related to biomass analysis are also illustrated. Chapter 2 and 3 comprise two published or submitted manuscripts, and the thesis concludes with an appendix. In Chapter 2, a Raman spectroscopic protocol is described to study the efficiency of enzymatic hydrolysis of cellulose by measuring the main product in hydrolysate, glucose. Two commonly utilized pretreatment methods were investigated in order to understand their effect on glucose measurements by Raman spectroscopy. Second, a similar method was set up to determine the concentration of ethanol in fermentation broth. Both of these measurements are challenged by the presence of complex matrices. In Chapter 3, a quantitative comparison of pretreatment protocols and the effect of enzyme composition are studied using systematic methods. A multipeak fitting algorithm was developed to …

In this Dissertation I present a detailed study of p$\bar{p}$ → WZ production using fully leptonic decays of W and Z bosons with electrons and muons in the final state. Data used for the study were collected by the DØ detector at the Fermilab p$\bar{p}$ collider with a center-of-mass energy of √s = 1.96 TeV and correspond to 4.1 fb^-1 of integrated luminosity. The most precise measurement of the WZ production cross section is obtained and found to be in a good agreement with the standard model prediction. I also present a search for new phenomena in the WZ production by investigating the coupling between W and Z bosons and by searching for new charged particles that can decay into WZ boson pair. No evidence for new physics is found, and the most stringent limits are set on the anomalous WWZ coupling parameters and masses of charged resonances. This result also sets the stringest limit on one of the possible sources of electroweak symmetry breaking, a low-scale Technicolor with a typical heavy techni-pion hypothesis.

Continually rising energy prices have inspired increased interest in weight reduction in the automotive and aerospace industries, opening the door for the widespread use and development of lightweight structural materials. Chief among these materials are cast Al-Si and magnesium-based alloys. Utilization of Al-Si alloys depends on obtaining a modified fibrous microstructure in lieu of the intrinsic flake structure, a process which is incompletely understood. The local solidification conditions, mechanisms, and tensile properties associated with the flake to fiber growth mode transition in Al-Si eutectic alloys are investigated here using bridgman type gradient-zone directional solidification. Resulting microstructures are examined through quantitative image analysis of two-dimensional sections and observation of deep-etched sections showing three-dimensional microstructural features. The transition was found to occur in two stages: an initial stage dominated by in-plane plate breakup and rod formation within the plane of the plate, and a second stage where the onset of out-of-plane silicon rod growth leads to the formation of an irregular fibrous structure. Several microstructural parameters were investigated in an attempt to quantify this transition, and it was found that the particle aspect ratio is effective in objectively identifying the onset and completion velocity of the flake to fiber transition. The appearance …

We present here the search for Standard Model V H → VWW → lll + E_T (missing energy due to neutrinos) production, where V is a W or Z weak vector boson, which uses up to 5.9 fb^-1 of integrated luminosity. This analysis has recently added to the CDF high-mass Higgs group three new signal topologies characterized by a tri-lepton signature, which are chosen to isolate the V H → VWW associated production signals in the three-lepton signature. As such, we define three new regions for a WH analysis, a ZH 1-jet analysis, and a ZH ≥ 2-jet analysis with which we expect to contribute an additional 5.8% (for mH = 165 GeV) acceptance to the current H → WW dilepton analysis. The ZH trilepton regions are defined by events passing a Z-boson selection: events having at least one lepton pairing (among three possible pairings) with opposite sign, same flavor, and a dilepton invariant mass within [76.0, 106.0] GeV–a ± 15 GeV window around the Z-boson mass. TheWH trilepton region is then defined as the set of trilepton events that are complement to those chosen by the Z-boson selection. These three new event topologies make a substantial contribution to the …

Quantum mechanical (QM) calculations have the advantage of attaining high-level accuracy, however QM calculations become computationally inefficient as the size of the system grows. Solving complex molecular problems on large systems and ensembles by using quantum mechanics still poses a challenge in terms of the computational cost. Methods that are based on classical mechanics are an inexpensive alternative, but they lack accuracy. A good trade off between accuracy and efficiency is achieved by combining QM methods with molecular mechanics (MM) methods to use the robustness of the QM methods in terms of accuracy and the MM methods to minimize the computational cost. Two types of QM combined with MM (QM/MM) methods are the main focus of the present dissertation: the application and development of QM/MM methods for solvation studies and reactions on the Si(100) surface. The solvation studies were performed using a discreet solvation model that is largely based on first principles called the effective fragment potential method (EFP). The main idea of combining the EFP method with quantum mechanics is to accurately treat the solute-solvent and solvent-solvent interactions, such as electrostatic, polarization, dispersion and charge transfer, that are important in correctly calculating solvent effects on systems of interest. A …

Oxide compounds containing the transition metal vanadium (V) have attracted a lot of attention in the field of condensed matter physics owing to their exhibition of interesting properties including metal-insulator transitons, structural transitions, ferromagnetic and an- tiferromagnetic orderings, and heavy fermion behavior. Binary vanadium oxides VnO_2n-1 where 2 ≤ n ≤ 9 have triclinic structures and exhibit metal-insulator and antiferromagnetic transitions.[1–6] The only exception is V₇O₁₃ which remains metallic down to 4 K.[7] The ternary vanadium oxide LiV₂O₄ has the normal spinel structure, is metallic, does not un- dergo magnetic ordering and exhibits heavy fermion behavior below 10 K.[8] CaV₂O₄ has an orthorhombic structure[9, 10] with the vanadium spins forming zigzag chains and has been suggested to be a model system to study the gapless chiral phase.[11, 12] These provide great motivation for further investigation of some known vanadium compounds as well as to ex- plore new vanadium compounds in search of new physics. This thesis consists, in part, of experimental studies involving sample preparation and magnetic, transport, thermal, and x- ray measurements on some strongly correlated eletron systems containing the transition metal vanadium. The compounds studied are LiV₂O₄, YV₄O₈, and YbV₄O₈. The recent discovery of superconductivity in RFeAsO_1-xF_x (R …

In summary, there are two major research works presented in this dissertation. The first research project (Chapter 4) is spectrally narrowed edge emission from Organic Light Emitting Diodes. The second project (Chapter 5) is about transient electroluminescent dynamics in OLEDs. Chapter 1 is a general introduction of OLEDs. Chapter 2 is a general introduction of organic semiconductor lasers. Chapter 3 is a description of the thermal evaporation method for OLED fabrication. The detail of the first project was presented in Chapter 4. Extremely narrowed spectrum was observed from the edge of OLED devices. A threshold thickness exists, above which the spectrum is narrow, and below which the spectrum is broad. The FWHM of spectrum depends on the material of the organic thin films, the thickness of the organic layers, and length of the OLED device. A superlinear relationship between the output intensity of the edge emission and the length of the device was observed, which is probably due to the misalignment of the device edge and the optical fiber detector. The original motivation of this research is for organic semiconductor laser that hasn't been realized due to the extremely high photon absorption in OLED devices. Although we didn't succeed in …

The search for the production of the Standard Model Z boson in association with a W boson is motivated and discussed. This is performed using 4.3 fb^-1 of Tevatron Run II data collected with the CDF detector in √s = 1.96 TeV proton anti-proton collisions. This is a signature-based analysis where the W boson decays semileptonically into a high-P_T electron or muon plus a neutrino, and where the Z boson decays into two b quark jets (b-jets). We increase the signal-to-background ratio by identifying the b-quarks in the jets with a new neural network-based algorithm. Another neural network then uses kinematic information to distinguish WZ to further increase the signal-to-background ratio. Since our sensitivity is still not enough to achieve an observation, we set a 95% Confidence Level upper limit on the product of the WZ production cross section and its branching fraction to the decay products specified above, and express it as a ratio to the theoretical Standard Model prediction. The resulting limit is 3.9 x SM (3.9 x SM expected).

The thesis is divided into two parts. In the first part a global optimization method is developed for the interface and surface structures optimization. Two prototype systems are chosen to be studied. One is Si[001] symmetric tilted grain boundaries and the other is Ag/Au induced Si(111) surface. It is found that Genetic Algorithm is very efficient in finding lowest energy structures in both cases. Not only existing structures in the experiments can be reproduced, but also many new structures can be predicted using Genetic Algorithm. Thus it is shown that Genetic Algorithm is a extremely powerful tool for the material structures predictions. The second part of the thesis is devoted to the explanation of an experimental observation of thermal radiation from three-dimensional tungsten photonic crystal structures. The experimental results seems astounding and confusing, yet the theoretical models in the paper revealed the physics insight behind the phenomena and can well reproduced the experimental results.

The cross-section times branching ratio of the Higgs boson decaying to τ⁺τ^- final state in the Standard Model (SM) is too small to play any role in the SM Higgs boson searches. This, however, is different in the Minimal Supersymmetric Standard Model (MSSM), which predicts two Higgs doublets leading to five Higgs bosons: a pair of charged Higgs boson (H^±); two neutral CP-even Higgs bosons (h,H) and a CP-odd Higgs boson (A). A search for the production of neutral Higgs bosons decaying into τ⁺τ^- final states in p{bar p} collisions at a centre-of-mass energy of √s = 1.96 TeV is presented in this thesis. One of the two τ leptons is required to decay into a muon while the other decays hadronically. The integrated luminosity is L = 1.0-5.36 fb ^-1, collected by the D0 experiment at the Fermilab Tevatron Collider from 2002 to 2009 in the Run II.

An inductively coupled plasma-mass spectrometer (ICP-MS) is an elemental analytical instrument capable of determining nearly all elements in the periodic table at limits of detection in the parts per quadrillion and with a linear analytical range over 8-10 orders of magnitude. Three concentric quartz tubes make up the plasma torch. Argon gas is spiraled through the outer tube and generates the plasma powered by a looped load coil operating at 27.1 or 40.6 MHz. The argon flow of the middle channel is used to keep the plasma above the innermost tube through which solid or aqueous sample is carried in a third argon stream. A sample is progressively desolvated, atomized and ionized. The torch is operated at atmospheric pressure. To reach the reduced pressures of mass spectrometers, ions are extracted through a series of two, approximately one millimeter wide, circular apertures set in water cooled metal cones. The space between the cones is evacuated to approximately one torr. The space behind the second cone is pumped down to, or near to, the pressure needed for the mass spectrometer (MS). The first cone, called the sampler, is placed directly in the plasma plume and its position is adjusted to the point …

Early measurements of a large forward-background asymmetry at the CDF and D0 experiments at Fermilab have generated much recent interest, but were hampered by large uncertainties. We present here a new measurement of the parton level forward-backward asymmetry of pair-produced top quarks, using a high-statistics sample with much improved precision. We study the rapidity, y_top, of the top quark production angle with respect to the incoming parton momentum in both the lab and t$\bar{t}$ rest frames. We find the parton-level forward-backward asymmetries to be A_fb^p$\bar{t}$ = 0.150 ± 0.050^stat ± 0.024^syst A_fb^t$\bar{t}$ = 0.158 ± 0.072{sup stat} ± 0.024^syst. These results should be compared with the small p$\bar{p}$ frame charge asymmetry expected in QCD at NLO, A_fb = 0.050 ± 0.015. Additionally, we introduce a measurement of the A_fb rapidity dependence dA_fb/d(Δy). We find this to be A_fb^p$\bar{t}$(|Δy| < 1.0) = 0.026 ± 0.104^stat ± 0.012 ^syst A_fb^p$\bar{t}$(|Δy| > 1.0) = 0.611 ± 0.210^stat ± 0.246^syst which we compare with model predictions 0.039 ± 0.006 and 0.123 ± 0.018 for the inner and outer rapidities, respectively.

Gamma ray detectors are important in national security applications, medicine, and astronomy. Semiconductor materials with high density and atomic number, such as Cadmium Telluride (CdTe), offer a small device footprint, but their performance is limited by noise at room temperature; however, improved device design can decrease detector noise by reducing leakage current. This thesis characterizes and models two unique Schottky devices: one with an argon ion sputter etch before Schottky contact deposition and one without. Analysis of current versus voltage characteristics shows that thermionic emission alone does not describe these devices. This analysis points to reverse bias generation current or leakage through an inhomogeneous barrier. Modeling the devices in reverse bias with thermionic field emission and a leaky Schottky barrier yields good agreement with measurements. Also numerical modeling with a finite-element physics-based simulator suggests that reverse bias current is a combination of thermionic emission and generation. This thesis proposes further experiments to determine the correct model for reverse bias conduction. Understanding conduction mechanisms in these devices will help develop more reproducible contacts, reduce leakage current, and ultimately improve detector performance.

There is now substantial evidence that the proper description of neutrino involves two representations related by the 3 x 3 PMNS matrix characterized by either distinct mass or flavor. The parameters of this mixing matrix, three angles and a phase, as well as the mass differences between the three mass eigenstates must be determined experimentally. The Main Injector Neutrino Oscillation Search experiment is designed to study the flavor composition of a beam of muon neutrinos as it travels between the Near Detector at Fermi National Accelerator Laboratory at 1 km from the target, and the Far Detector in the Soudan iron mine in Minnesota at 735 km from the target. From the comparison of reconstructed neutrino energy spectra at the near and far location, precise measurements of neutrino oscillation parameters from muon neutrino disappearance and electron neutrino appearance are expected. It is very important to know the neutrino flux coming from the source in order to achieve the main goal of the MINOS experiment: precise measurements of the atmospheric mass splitting |Δm₂₃²|, sin² θ₂₃. The goal of my thesis is to accurately predict the neutrino flux for the MINOS experiment and measure the neutrino mixing angle and atmospheric mass splitting.

The motivation of this dissertation was to advance the study of Yb-based heavy fermion (HF) compounds especially ones related to quantum phase transitions. One of the topics of this work was the investigation of the interaction between the Kondo and crystalline electric field (CEF) energy scales in Yb-based HF systems by means of thermoelectric power (TEP) measurements. In these systems, the Kondo interaction and CEF excitations generally give rise to large anomalies such as maxima in ρ(T) and as minima in S(T). The TEP data were use to determine the evolution of Kondo and CEF energy scales upon varying transition metals for YbT₂Zn₂₀ (T = Fe, Ru, Os, Ir, Rh, and Co) compounds and applying magnetic fields for YbAgGe and YbPtBi. For YbT₂Zn₂₀ and YbPtBi, the Kondo and CEF energy scales could not be well separated in S(T), presumably because of small CEF level splittings. A similar effect was observed for the magnetic contribution to the resistivity. For YbAgGe, S(T) has been successfully applied to determine the Kondo and CEF energy scales due to the clear separation between the ground state and thermally excited CEF states. The Kondo temperature, T_K, inferred from the local maximum in S(T), remains finite as …

General introduction to OLED basics and OLED-based structurally integrated sensors was provided in chapter 1 and chapter 2. As discussed in chapter 3, OLEDs were developed or improved using novel engineering methods for better charge injection (increased by over 1 order of magnitude) and efficiency. As the excitation sources, these OLEDs have preferred characteristics for sensor applications, including narrowed emission, emission at desired wavelength, and enhanced output for reduced EL background, higher absorption and improved device lifetime. In addition to OLEDs with desired performance, sensor integration requires oxidase immobilization with the sensor film for O₂-based biological and chemical sensing. Nanoparticles such as ZnO have large surface area and high isoelectric point (~9.5), which favors enzyme immobilization via physical adsorption as well as Coulombic bonding. In chapter 4, it was demonstrated that ZnO could be used for this purpose, although future work is needed to further bond the ZnO to the sensor film. In chapter 5, single unit sensor was extended to multianalyte parallel sensing based on an OLED platform, which is compact and integrated with silicon photodiodes and electronics. Lactate and glucose were simultaneously monitored with a low limit of detection 0.02 mM, fast response time (~1 minute) and dynamic …

The complicated physical phenomena in complex transition-metal oxides (TMO), such as high T_c superconductivity, colossal magnetoresistivity, metal-insulator transitions, etc., have long been the focus of intense inquiry and debate in condensed matter science, since they are related to strong electronic correlations and cannot be explained within the 'standard model' of solid state physics. These novel functionalities of the correlated electron systems have a wide range of potential for applications in industry, such as information storage, energy transportation, and so on. The charge-ordering (CO) transition is very common in TMO and there is a specific CO transition temperature, TCO. Above TCO, the charge is not ordered, which means that the electrons in a compound are itinerant and the positions of the electrons are not fixed. Below TCO, the charge is ordered, which means that the electrons are localized and the positions of the electrons are settled. Hence, the electrical conductivity of a material is changed at TCO and this transition is classified as metal-insulator transition. Usually the CO with commensurate hole doping in TMO is thought to play an important role in various cases, including the superconducting cuprates, where the spin/charge stripe formation competes with superconducting states, colossal magnetoresistive manganites, where …