Language

On the hypothesis that quantum mechanism manifests classical mechanics: Numerical approach to the correspondence in search of quantum chaos (open access)

On the hypothesis that quantum mechanism manifests classical mechanics: Numerical approach to the correspondence in search of quantum chaos

Quantum manifestation of classical chaos has been one of the extensively studied subjects for more than a decade. Yet clear understanding of its nature still remains to be an open question partly due to the lack of a canonical definition of quantum chaos. The classical definition seems to be unsuitable in quantum mechanics partly because of the Heisenberg quantum uncertainty. In this regard, quantum chaos is somewhat misleading and needs to be clarified at the very fundamental level of physics. Since it is well known that quantum mechanics is more fundamental than classical mechanics, the quantum description of classically chaotic nature should be attainable in the limit of large quantum numbers. The focus of my research, therefore, lies on the correspondence principle for classically chaotic systems. The chaotic damped driven pendulum is mainly studied numerically using the split operator method that solves the time-dependent Schroedinger equation. For classically dissipative chaotic systems in which (multi)fractal strange attractors often emerge, several quantum dissipative mechanisms are also considered. For instance, Hoover`s and Kubo-Fox-Keizer`s approaches are studied with some computational analyses. But the notion of complex energy with non-Hermiticity is extensively applied. Moreover, the Wigner and Husimi distribution functions are examined with an equivalent …
Date: September 1, 1993
Creator: Lee, Sang-Bong
System: The UNT Digital Library
Reaction and reorientation of electronically excited H{sub 2}(B) (open access)

Reaction and reorientation of electronically excited H{sub 2}(B)

The room temperature rate (TR) constants for fluorescence quenching fluorescence of H{sub 2}, HD, and D{sub 2} B {sup 1}{Sigma}{sub u}{sup +} by {sup 4}He were measured as a function of the initially excited rotational and vibrational level of the hydrogen molecule, and the RT rate constants for molecular angular momentum reorientation of H{sub 2}, HD and D{sub 2} (B {sup 1}{Sigma}{sub u}{sup +}. v{prime}=0, J{prime}=1, M{sub J}=0) in collisions with He, Ne, Ar and H{sub 2}(X {sup 1}{Sigma}{sub g}{sup +}) were also measured. Vibrational state dependence of the quenching cross sections fits a vibrationally adiabatic model of the quenching process. From the vibrational state dependence of the quenching cross section, the barrier height for the quenching reaction is found to be 250{plus_minus}40 cm{sup {minus}1}, and the difference in the H-H stretching frequencies between H{sub 2}(B) and the H{sub 2}-He complex at the barrier to reaction is 140{plus_minus}80 cm{sup {minus}1}. The effective cross sections for angular momentum reorientation in collisions of H{sub 2}, HD, D{sub 2} with He and Ne were found to be about 30 {Angstrom}{sup 2} and were nearly the same for each isotope and with He and Ne as collision partners. Cross sections forreorientation of HD and …
Date: September 1, 1992
Creator: Pibel, C. D.
System: The UNT Digital Library
Enhanced algorithms for stochastic programming (open access)

Enhanced algorithms for stochastic programming

In this dissertation, we present some of the recent advances made in solving two-stage stochastic linear programming problems of large size and complexity. Decomposition and sampling are two fundamental components of techniques to solve stochastic optimization problems. We describe improvements to the current techniques in both these areas. We studied different ways of using importance sampling techniques in the context of Stochastic programming, by varying the choice of approximation functions used in this method. We have concluded that approximating the recourse function by a computationally inexpensive piecewise-linear function is highly efficient. This reduced the problem from finding the mean of a computationally expensive functions to finding that of a computationally inexpensive function. Then we implemented various variance reduction techniques to estimate the mean of a piecewise-linear function. This method achieved similar variance reductions in orders of magnitude less time than, when we directly applied variance-reduction techniques directly on the given problem. In solving a stochastic linear program, the expected value problem is usually solved before a stochastic solution and also to speed-up the algorithm by making use of the information obtained from the solution of the expected value problem. We have devised a new decomposition scheme to improve the convergence …
Date: September 1, 1993
Creator: Krishna, A. S.
System: The UNT Digital Library
Study of the effect of humidity, particle hygroscopicity and size on the mass loading capacity of HEPA filters (open access)

Study of the effect of humidity, particle hygroscopicity and size on the mass loading capacity of HEPA filters

The effect of humidity, particle hygroscopicity and size on the mass loading capacity of glass fiber HEPA filters has been studied. At humidifies above the deliquescent point, the pressure drop across the HEPA filter increased non-linearly with the areal loading density (mass collected/filtration area) of NaCl aerosol, thus significantly reducing the mass loading capacity of the filter compared to dry hygroscopic or non-hygroscopic particle mass loadings. The specific cake resistance, K{sub 2}, has been computed for different test conditions and used as a measure of the mass loading capacity. K. was found to decrease with increasing humidity for the non-hygroscopic aluminum oxide particles and the hygroscopic NaCl particles (at humidities below the deliquescent point). It is postulated that an increase in humidity leads to the formation of a more open particulate cake which lowers the pressure drop for a given mass loading. A formula for predicting K{sub 2} for lognormally distributed aerosols (parameters obtained from impactor data) is derived. The resistance factor, R, calculated using this formula was compared to the theoretical R calculated using the Rudnick-Happel expression. For the non-hygroscopic aluminum oxide the agreement was good but for the hygroscopic sodium chloride, due to large variation in the cake …
Date: September 1, 1992
Creator: Gupta, A.
System: The UNT Digital Library
Carbon doping of III-V compound semiconductors (open access)

Carbon doping of III-V compound semiconductors

Focus of the study is C acceptor doping of GaAs, since C diffusion coefficient is at least one order of magnitude lower than that of other common p-type dopants in GaAs. C ion implantation results in a concentration of free holes in the valence band < 10% of that of the implanted C atoms for doses > 10{sup 14}/cm{sup 2}. Rutherford backscattering, electrical measurements, Raman spectroscopy, and Fourier transform infrared spectroscopy were amonth the techniques used. Ga co-implantation increased the C activation in two steps: first, the additional radiation damage creates vacant As sites that the implanted C can occupy, and second, it maintains the stoichiometry of the implanted layer, reducing the number of compensating native defects. In InP, the behavior of C was different from that in GaAs. C acts as n-type dopant in the In site; however, its incorporation by implantation was difficult to control; experiments using P co-implants were inconsistent. The lattice position of inactive C in GaAs in implanted and epitaxial layers is discussed; evidence for formation of C precipitates in GaAs and InP was found. Correlation of the results with literature on C doping in III-V semiconductors led to a phenomenological description of C in …
Date: September 1, 1994
Creator: Moll, A. J.
System: The UNT Digital Library
Laser trapping of {sup 21}Na atoms (open access)

Laser trapping of {sup 21}Na atoms

This thesis describes an experiment in which about four thousand radioactive {sup 21}Na (t{sub l/2} = 22 sec) atoms were trapped in a magneto-optical trap with laser beams. Trapped {sup 21}Na atoms can be used as a beta source in a precision measurement of the beta-asymmetry parameter of the decay of {sup 21}Na {yields} {sup 21}Ne + {Beta}{sup +} + v{sub e}, which is a promising way to search for an anomalous right-handed current coupling in charged weak interactions. Although the number o trapped atoms that we have achieved is still about two orders of magnitude lower than what is needed to conduct a measurement of the beta-asymmetry parameter at 1% of precision level, the result of this experiment proved the feasibility of trapping short-lived radioactive atoms. In this experiment, {sup 21}Na atoms were produced by bombarding {sup 24}Mg with protons of 25 MeV at the 88 in. Cyclotron of Lawrence Berkeley Laboratory. A few recently developed techniques of laser manipulation of neutral atoms were applied in this experiment. The {sup 21}Na atoms emerging from a heated oven were first transversely cooled. As a result, the on-axis atomic beam intensity was increased by a factor of 16. The atoms in …
Date: September 1, 1994
Creator: Lu, Zheng-Tian
System: The UNT Digital Library
Beam Diagnosis and Lattice Modeling of the Fermilab Booster (open access)

Beam Diagnosis and Lattice Modeling of the Fermilab Booster

A realistic lattice model is a fundamental basis for the operation of a synchrotron. In this study various beam-based measurements, including orbit response matrix (ORM) and BPM turn-by-turn data are used to verify and calibrate the lattice model of the Fermilab Booster. In the ORM study, despite the strong correlation between the gradient parameters of adjacent magnets which prevents a full determination of the model parameters, an equivalent lattice model is obtained by imposing appropriate constraints. The fitted gradient errors of the focusing magnets are within the design tolerance and the results point to the orbit offsets in the sextupole field as the source of gradient errors. A new method, the independent component analysis (ICA) is introduced to analyze multiple BPM turn-by-turn data taken simultaneously around a synchrotron. This method makes use of the redundancy of the data and the time correlation of the source signals to isolate various components, such as betatron motion and synchrotron motion, from raw BPM data. By extracting clean coherent betatron motion from noisy data and separates out the betatron normal modes when there is linear coupling, the ICA method provides a convenient means to measure the beta functions and betatron phase advances. It also …
Date: September 1, 2005
Creator: Huang, Xiaobiao
System: The UNT Digital Library
First Search for the Standard Model Higgs Boson Using the Semileptonic Decay Channel: H --> WW --> mu bar nu jj (open access)

First Search for the Standard Model Higgs Boson Using the Semileptonic Decay Channel: H --> WW --> mu bar nu jj

This dissertation presents the first search for the standard model Higgs boson (H) in decay topologies containing a muon, an imbalance in transverse momentum (E{sub T}) and jets, using p{bar p} collisions at {radical}s = 1.96 TeV with an integrated luminosity of 4.3 fb{sup -1} recorded with the D0 detector at the Fermilab Tevatron Collider. This analysis is sensitive primary to contributions from Higgs bosons produced through gluon fusion, with subsequent decay H {yields} WW {yields} {mu}{nu}jj where W represents a real or virtual W boson. In the absence of signal, limits are set at 95% confidence on the production and decay of the standard model Higgs boson for M{sub H} in the range of 115-200 GeV. For M{sub H} = 165 GeV, the observed and expected limits are factors of 11.2 larger than the standard model value. Combining this channel with e{nu}jj final states and including earlier data to increase the integrated luminosity to 5.4 fb{sup -1} produces observed(expected) limits of 5.5(3.8) times the standard model value.
Date: September 1, 2010
Creator: Zelitch, Shannon Maura & U., /Virginia
System: The UNT Digital Library
A Sterile-Neutrino Search with the MINOS Experiment (open access)

A Sterile-Neutrino Search with the MINOS Experiment

The MINOS experiment is a long-baseline neutrino oscillation experiment in the the NuMI beamline at Fermilab, USA. Using a near detector at 1 km distance from the neutrino production target, and a far detector at 735 km from the target, it is designed primarily to measure the disappearance of muon neutrinos. This thesis presents an analysis using MINOS data of the possibility of oscil- lation of the neutrinos in the NuMI beam to a hypothetical sterile flavour, which would have no Standard Model couplings. Such oscillations would result in a deficit in the neutral current interaction rate in the MINOS far detector relative to the expectation derived from the near detector data. The method used to identify neutral current and charged current events in the MINOS detectors is described and a new method of predicting and fitting the far detector spectrum presented, along with the effects of systematic uncertainties on the sterile neutrino oscillation analysis. Using this analysis, the fraction f{sub s} of the disappearing neutrinos that go to steriles is constrained to be below 0.15 at the 90% confidence level in the absence of electron neutrino appearance in the NuMI beam. With electron appearance at the CHOOZ limit, f{sub …
Date: September 1, 2010
Creator: Rodrigues, Philip
System: The UNT Digital Library
Polarized {sup 3}He(e,e'n) Asymmetries in Three Orthogonal Measurements (open access)

Polarized {sup 3}He(e,e'n) Asymmetries in Three Orthogonal Measurements

Asymmetry measurements were conducted in Jefferson Lab's experimental Hall A through electron scattering from a polarized {sup 3}He target in the quasi-elastic polarized-{sup 3}He(e,e'n) reaction. Measurements were made with the target polarized in the longitudinal direction with respect to the incoming electrons A_L, in a transverse direction that was orthogonal to the beam-line and parallel to the q-vector A_T, and in a vertical direction that was orthogonal to both the beam-line and the q-vector (A_y^0). The experiment measured $A_y^0$ at four-momentum transfer squared Q^2 of 0.127 (GeV/c)^2, 0.456 (GeV/c)^2, and 0.953 (GeV/c)^2. The A_T and A_L asymmetries were both measured at Q^2 of 0.505 (GeV/c)^2 and 0.953 (GeV/c)^2. This is the first time that three orthogonal asymmetries have been measured simultaneously. Results from this experiment are compared with the plane wave impulse approximation (PWIA) and Faddeev calculations. These results provide important tests of models that use 3He as an effective neutron target and show that the PWIA holds above Q^2 of 0.953 (GeV/c)^2.
Date: September 1, 2012
Creator: Long, Elena
System: The UNT Digital Library
Analysis and Development of FACE Automatic Apparatus for Rapid Identification of Transuranium Isotopes (open access)

Analysis and Development of FACE Automatic Apparatus for Rapid Identification of Transuranium Isotopes

A description of and operating manual for the FACE Automatic Apparatus has been written along with a documentation of the FACE machine operating program, to provide a user manual for the FACE Automatic Apparatus. In addition, FACE machine performance was investigated to improve transuranium throughput. Analysis of the causes of transuranium isotope loss was undertaken both chemical and radioactive. To lower radioactive loss, the dynamics of the most time consuming step of the FACE machine, the chromatographic column output droplet drying and flaming, in preparation of sample for alpha spectroscopy and counting, was investigated. A series of droplets were dried in an experimental apparatus demonstrating that droplets could be dried significantly faster through more intensie heating, enabling the FACE machine cycle to be shortened by 30-60 seconds. Proposals incorporating these ideas were provided for FACE machine development. The 66% chemical loss of product was analyzed and changes were proposed to reduce the radioisotopes product loss. An analysis of the chromatographic column was also provided. All operating steps in the FACE machine are described and analyzed to provide a complete guide, along with the proposals for machine improvement.
Date: September 1, 1978
Creator: Sebesta, E.H.
System: The UNT Digital Library
Study of the top quark electric charge at the CDF experiment (open access)

Study of the top quark electric charge at the CDF experiment

We report on the measurement of the top quark electric charge using the jet charge tagging method on events containing a single lepton collected by the CDF II detector at Fermilab between February 2002 and February 2010 at the center-of-mass energy {radical}s = 1.96 TeV. There are three main components to this measurement: determining the charge of the W (using the charge of the lepton), pairing the W with the b-jet to ensure that they are from the same top decay branch and finally determining the charge of the b-jet using the Jet Charge algorithm. We found, on a sample of 5.6 fb{sup -1} of data, that the p-value under the standard model hypothesis is equal to 13.4%, while the p-value under the exotic model hypothesis is equal to 0.014%. Using the a priori criteria generally accepted by the CDF collaboration, we can say that the result is consistent with the standard model, while we exclude an exotic quark hypothesis with 95% confidence. Using the Bayesian approach, we obtain for the Bayes factor (2ln(BF)) a value of 19.6, that favors very strongly the SM hypothesis over the XM one. The presented method has the highest sensitivity to the top quark …
Date: September 1, 2011
Creator: Bartos, Pavol
System: The UNT Digital Library
Cubic to tetragonal crystal lattice reconstruction during ordering or decomposition (open access)

Cubic to tetragonal crystal lattice reconstruction during ordering or decomposition

This thesis studied thermodynamic stability and morphology of product phases in diffusional phase transformations involving cubic-to-tetragonal crystal lattice reconstructions. Two different kinds of diffusional transformations were examined: L1{sub 0} ordering (fcc to fct lattice change) and decomposition of off-stoichiometric B2 ordering alloys accompanying bcc to fcc Bain transformation. In the first case, Fe-45 at.% Pd alloys were studied by TEM; in the second, the Bain strain relaxation during decomposition of hyper-eutectoid Cu-9.04 wt% Be alloy was studied. CuAu and InMg were also studied.
Date: September 1, 1992
Creator: Cheong, Byung-kl
System: The UNT Digital Library
Laser cooling of a stored ion beam: A first step towards crystalline beams (open access)

Laser cooling of a stored ion beam: A first step towards crystalline beams

This report discusses: a brief introduction to storage rings; crystalline beams; laser cooling of ion beams; description of astrid-the experimental setup; first experiments with lithium 7 ion beam; experiments with erbium 166 ion beams; further experiments with lithium 7 ion beams; beam dynamics, laser cooling,and crystalline beams in astrid; possibilities for further study in astrid.
Date: September 1, 1992
Creator: Hangst, J. S.
System: The UNT Digital Library
MINOS Sterile Neutrino Search (open access)

MINOS Sterile Neutrino Search

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.
System: The UNT Digital Library
Search for the Standard Model Higgs boson in the decay mode H-> WW-> lnulnu (open access)

Search for the Standard Model Higgs boson in the decay mode H-> WW-> lnulnu

The question of the nature and principles of the universe and our place in it is the driving force of science since Mesopotamian astronomers glanced for the first time at the starry sky and Greek atomism has been formulated. During the last hundred years modern science was able to extend its knowledge tremendously, answering many questions, opening entirely new fields but as well raising many new questions. Particularly Astronomy, Astroparticle Physics and Particle Physics lead the race to answer these fundamental and ancient questions experimentally. Today it is known that matter consists of fermions, the quarks and leptons. Four fundamental forces are acting between these particles, the electromagnetic, the strong, the weak and the gravitational force. These forces are mediated by particles called bosons. Our confirmed knowledge of particle physics is based on these particles and the theory describing their dynamics, the Standard Model of Particles. Many experimental measurements show an excellent agreement between observation and theory but the origin of the particle masses and therefore the electroweak symmetry breaking remains unexplained. The mechanism proposed to solve this issue involves the introduction of a complex doublet of scalar fields which generates the masses of elementary particles via their mutual interactions. …
Date: September 1, 2009
Creator: Penning, B.
System: The UNT Digital Library
Neutral Supersymmetric Higgs Boson Searches (open access)

Neutral Supersymmetric Higgs Boson Searches

In some Supersymmetric extensions of the Standard Model, including the Minimal Supersymmetric Standard Model (MSSM), the coupling of Higgs bosons to b-quarks is enhanced. This enhancement makes the associated production of the Higgs with b-quarks an interesting search channel for the Higgs and Supersymmetry at D0. The identification of b-quarks, both online and offline, is essential to this search effort. This thesis describes the author's involvement in the development of both types of b-tagging and in the application of these techniques to the MSSM Higgs search. Work was carried out on the Level-3 trigger b-tagging algorithms. The impact parameter (IP) b-tagger was retuned and the effects of increased instantaneous luminosity on the tagger were studied. An extension of the IP-tagger to use the z-tracking information was developed. A new b-tagger using secondary vertices was developed and commissioned. A tool was developed to allow the use of large multi-run samples for trigger studies involving b-quarks. Offline, a neural network (NN) b-tagger was trained combining the existing offline lifetime based b-tagging tools. The efficiency and fake rate of the NN b-tagger were measured in data and MC. This b-tagger was internally reviewed and certified by the Collaboration and now provides the official …
Date: September 1, 2009
Creator: Robinson, Stephen Luke
System: The UNT Digital Library
Measuring Antineutrino Oscillations with the MINOS Experiment (open access)

Measuring Antineutrino Oscillations with the MINOS Experiment

MINOS is a long baseline neutrino oscillation experiment. A manmade beam of predominantly muon neutrinos is detected both 1 km and 735 km from the production point by two functionally identical detectors. A comparison of the energy spectra measured by the two detectors shows the energy-dependent disappearance of muon neutrinos characteristic of oscillations and allows a measurement of the parameters governing the oscillations. This thesis presents work leading to measurements of disappearance in the 6% {bar {nu}}{sub {mu}} background in that beam. A calibration is developed to correct for time-dependent changes in the responses of both detectors, reducing the corresponding uncertainty on hadronic energy measurements from 1.8% to 0.4% in the near detector and from 0.8% to 0.4% in the far detector. A method of selecting charged current {bar {nu}}{sub {mu}} events is developed, with purities (efficiencies) of 96.5% (74.4%) at the near detector, and 98.8% (70.9%) at the far detector in the region below 10 GeV reconstructed antineutrino energy. A method of using the measured near detector neutrino energy spectrum to predict that expected at the far detector is discussed, and developed for use in the {bar {nu}}{sub {mu}} analysis. Sources of systematic uncertainty contributing to the oscillation measurements …
Date: September 1, 2008
Creator: Evans, Justin John
System: The UNT Digital Library
Self-Consistent Cosmological Simulations of DGP Braneworld Gravity (open access)

Self-Consistent Cosmological Simulations of DGP Braneworld Gravity

We perform cosmological N-body simulations of the Dvali-Gabadadze-Porrati braneworld model, by solving the full non-linear equations of motion for the scalar degree of freedom in this model, the brane bending mode. While coupling universally to matter, the brane-bending mode has self-interactions that become important as soon as the density field becomes non-linear. These self-interactions lead to a suppression of the field in high-density environments, and restore gravity to General Relativity. The code uses a multi-grid relaxation scheme to solve the non-linear field equation in the quasi-static approximation. We perform simulations of a flat self-accelerating DGP model without cosmological constant. However, the type of non-linear interactions of the brane-bending mode, which are the focus of this study, are generic to a wide class of braneworld cosmologies. The results of the DGP simulations are compared with standard gravity simulations assuming the same expansion history, and with DGP simulations using the linearized equation for the brane bending mode. This allows us to isolate the effects of the non-linear self-couplings of the field which are noticeable already on quasi-linear scales. We present results on the matter power spectrum and the halo mass function, and discuss the behavior of the brane bending mode within cosmological …
Date: September 1, 2009
Creator: Schmidt, Fabian & /Chicago U., Astron. Astrophys. Ctr. /KICP, Chicago
System: The UNT Digital Library
t anti-t production cross section measurement using soft electron tagging in p anti-p collisions at s**(1/2) = 1.96-TeV (open access)

t anti-t production cross section measurement using soft electron tagging in p anti-p collisions at s**(1/2) = 1.96-TeV

We measure the production cross section of t{bar t} events in p{bar p} collisions at {radical}s = 1.96 TeV. The data was collected by the CDF experiment in Run 2 of the Tevatron accelerator at the Fermi National Accelerator Laboratory between 2002 and 2007. 1.7 fb{sup -1} of data was recorded during this time period. We reconstruct t{bar t} events in the lepton+jets channel, whereby one W boson - resulting from the decay of the top quark pairs - decays leptonically and the other hadronically. The dominant background to this process is the production of W bosons in association with multiple jets. To distinguish t{bar t} from background, we identify soft electrons from the semileptonic decay of heavy flavor jets produced in t{bar t} events. We measure a cross section of {sigma}{sub p{bar p}} = 7.8 {+-} 2.4(stat) {+-} 1.6(syst) {+-} 0.5(lumi).
Date: September 1, 2008
Creator: Chou, John Paul & U., /Harvard
System: The UNT Digital Library
Observations and Measurements of Orbitally Excited L=1 B Mesons at the D0 Experiment (open access)

Observations and Measurements of Orbitally Excited L=1 B Mesons at the D0 Experiment

This thesis describes investigations of the first set of orbitally excited (L = 1) states for both the B{sub d}{sup 0} and B{sub s}{sup 0} meson systems (B**{sub d} and B**{sub s}). The data sample corresponds to 1.35 fb{sup -1} of integrated luminosity, collected in 2002-2006 by the D0 detector, during the Run IIa operation of the Tevatron p{bar p} colliding beam accelerator. The B**{sub d} states are fully reconstructed in decays to B{sup (*)+} {pi}{sup -}, with B{sup (*)+} {yields} {gamma} J/{psi}K{sup +}, J/{psi} {yields} {mu}{sup +}{mu}{sup -}, yielding 662 {+-} 91 events, and providing the first strong evidence for the resolution of two narrow resonances, B{sub 1} and B*{sub 2}. The masses are extracted from a binned {chi}{sup 2} fit to the invariant mass distribution, giving M(B{sub 1}) = 5720.7 {+-} 2.4(stat.) {+-} 1.3(syst.) {+-} 0.5 (PDG) MeV/c{sup 2} and M(B*{sub 2}) = 5746.9 {+-} 2.4(stat.) {+-} 1.0(syst.) {+-} 0.5(PDG) MeV/c{sup 2}. The production rate of narrow B**{sub d} {yields} B{pi} resonances relative to the B{sup +} meson is determined to be [13.9 {+-} 1.9(stat.) {+-} 3.2(syst.)]%. The same B{sup +} sample is also used to reconstruct the analogous states in the B{sub s}{sup 0} system, in decays …
Date: September 1, 2008
Creator: Williams, Mark Richard James
System: The UNT Digital Library
Hard photo-disintegration of proton pairs in {sup 3}He nuclei (open access)

Hard photo-disintegration of proton pairs in {sup 3}He nuclei

Extensive studies of high-energy deuteron photodisintegration over the past two decades have probed the limits of meson-baryon descriptions of nuclei and nuclear reactions. At high energies, photodisintegration cross sections have been shown to scale as a power law in s (the total cm energy squared), which suggests that quarks are the relevant degrees of freedom. In an attempt to more clearly identify the underlying dynamics at play, JLab/Hall A experiment 03-101 measured the hard photodisintegration of {sup 3}He into p-p and p-d pairs at θ{sub c.m.} = 90◦ and E{sub {gamma}} = 0.8 - 4.7 GeV. The basic idea is that the measurement should be able to test theoretical predictions for the relative size of pp versus pn disintegrations. This document presents data for the energy dependence of the high energy 90◦ c.m. photodisintegration of {sup3]He: dσ/dt(γ + {sup3}He → p + p + n{sub spectator}), and dσ/dt(γ + {sup 3}He → p + d). The cross sections were observed to scale as a function of s{sup −n} where n was found to be 11.1±0.1 and 17.4±0.5 for the two reactions respectively. The degree of scaling found for d#27;{sigma}/dt (γ + {sup 3}He → p + d) is the highest …
Date: September 1, 2011
Creator: Pomerantz, Ishay
System: The UNT Digital Library
Search for Supersymmetry in the Dilepton Final State with Taus at CDF Run II (open access)

Search for Supersymmetry in the Dilepton Final State with Taus at CDF Run II

This thesis presents the results a search for chargino and neutralino supersymmetric particles yielding same signed dilepton final states including one hadronically decaying tau lepton using 6.0 fb{sup -1} of data collected by the the CDF II detector. This signature is important in SUSY models where, at high tan {beta}, the branching ratio of charginos and neutralinos to tau leptons becomes dominant. We study event acceptance, lepton identification cuts, and efficiencies. We set limits on the production cross section as a function of SUSY particle mass for certain generic models.
Date: September 1, 2011
Creator: Forrest, Robert David
System: The UNT Digital Library
Search for Large Extra Dimensions Based on Observations of Neutron Stars with the Fermi-LAT (open access)

Search for Large Extra Dimensions Based on Observations of Neutron Stars with the Fermi-LAT

Large extra dimensions (LED) have been proposed to account for the apparent weakness of gravitation. These theories also indicate that the postulated massive Kaluza-Klein (KK) gravitons may be produced by nucleon-nucleon bremsstrahlung in the course of core collapse of supernovae. Hannestad and Raffelt have predicted energy spectra of gamma ray emission from the decay of KK gravitons trapped by the gravity of the remnant neutron stars (NS). These and other authors have used EGRET data on NS to obtain stringent limits on LED. Fermi-LAT is observing radio pulsar positions obtained from radio and x-ray catalogs. NS with certain characteristics are unlikely emitter of gamma rays, and emit in radio and perhaps x-rays. This talk will focus on the blind analysis we plan to perform, which has been developed using the 1st 2 months of all sky data and Monte Carlo simulations, to obtain limits on LED based on about 1 year of Fermi-LAT data. Preliminary limits from this analysis using these first 2 months of data will be also be discussed.
Date: September 19, 2012
Creator: Berenji, Bijan & /Stanford U., Appl. Phys. Dept. /SLAC
System: The UNT Digital Library