Digital Commons Network^™

Search For Excited And Exotic Electrons In The E Γ Decay Channel In Pp̅ Collisions At √S =1.96 Tev, Darin Acosta, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We present a search for excited and exotic electrons (e*) decaying to an electron and a photon, both with high transverse momentum. We use 202 pb^-1 of data collected in pp̅ collisions at √s =1.96 TeV with the Collider Detector at Fermilab II detector. No signal above standard model expectation is seen for associated ee* production. We discuss the e* sensitivity in the parameter space of the excited electron mass M_e^* and the compositeness energy scale Λ. In the contact interaction model, we exclude 132 GeV/c²e^*/c² for Λ =M_e^* at …

Measurement Of The Moments Of The Hadronic Invariant Mass Distribution In Semileptonic B Decays, Darin Acosta, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

Using 180 pb^-1 of data collected with the CDF II detector at the Tevatron, we measure the first two moments of the hadronic invariant mass-squared distribution in charmed semileptonic B decays. From these we determine the nonperturbative Heavy Quark Effective Theory parameters Λ and λ₁ used to relate the B meson semileptonic branching ratio to the CKM matrix element |V_cb|. For a minimum lepton momentum of 0.7 GeV/c in the B rest frame we measure the first two moments of the D^**→D^(*) π component to be D^**2>=(5.83±0.16stat±0.08syst) GeV …

Search For WBb̅ And Wh Production In Pp̅ Collisions At √S = 1.96 Tev, V. M. Abazov, Gregory R. Snow, D0 Collaboration

Gregory Snow Publications

We present a search for Wbb̅ production in pp̅ collisions at √s = 1.96 TeV in events containing one electron, an imbalance in transverse momentum, and two b-tagged jets. Using 174 pb^-1 of integrated luminosity accumulated by the D0 experiment at the Fermilab Tevatron collider, and the standard-model description of such events, we set a 95% C.L. upper limit on Wbb̅ production of 6.6 pb for b quarks with transverse momenta p_T^b > 20 GeV and bb̅ separation in pseudorapidity-azimuth space ΔR_bb > 0.75. Restricting the search to optimized bb̅ mass intervals provides …

First Measurements Of Inclusive W And Z Cross Sections From Run Ii Of The Fermilab Tevatron Collider, Darin Acosta, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We report the first measurements of inclusive W and Z cross sections times leptonic branching ratios for pp̅ collisions at √s =1.96 TeV, based on their decays to electrons and muons. The data correspond to an integrated luminosity of 72 pb^-1 recorded with the CDF detector at the Fermilab Tevatron. We test e-µ universality in W decays, and we measure the ratio of leptonic W and Z rates from which the leptonic branching fraction B (W→ ℓν) can be extracted as well as an indirect value for the total width of the W and the Cabibbo-Kobayashi-Maskawa matrix …

Measurement Of The Α Asymmetry Parameter For The Ω-→Λk- Decay, Y. C. Chen, Timothy Holmstrom, Hypercp Collaboration

Chemistry & Physics Faculty Publications

We have measured the α parameter of the Ω^-→ΛK^- decay using data collected with the HyperCP spectrometer during the 1997 fixed-target run at Fermilab. Analyzing a sample of 0.96×10⁶ Ω^-→ΛK^-, Λ→pπ^- decays, we obtain α_Ωα_Λ=[1.33±0.33(stat)±0.52(syst)]×10^-2. With the accepted value ofα_Λ, α_Ω is found to be [2.07±0.51(stat)±0.81(syst)]×10^-2.

Theoretical He I Emissivities In The Case B Approximation, R. L. Porter, R. P. Bauman, Gary J. Ferland, K. B. Macadam

Physics and Astronomy Faculty Publications

We calculate the He I case B recombination cascade spectrum using improved radiative and collisional data. We present new emissivities over a range of electron temperatures and densities. The differences between our results and the current standard are large enough to have a significant effect not only on the interpretation of observed spectra of a wide variety of objects, but also on determinations of the primordial helium abundance.

Using Liquid Crystal Spatial Light Modulators For Closed Loop Tracking And Beam Steering With Phase Holography, Michael J. Perry

Theses and Dissertations

Optical Phased Array (OPA) technology offers advantages in the reduction of size, weight, and power of optical steering devices. Nematic liquid crystal (LC) spatial light modulators (SLMs) have been studied as a potential candidate for building non-mechanical OPAs. They can steer a laser beam and split the beam into multiple beams. This thesis builds upon the prior research showing each split beam can be individually controlled, including variation in intensity. A closed loop tracking scenario shows the flexibility of the SLM by tracking and stabilizing an incoming beam. Results show that applying a phase grating to the SLM has limitations …

Angular Momentum Partitioning And The Subshell Multipole Moments In Impulsively Excited Argon Ions, H. M. Al-Khateeb, B. G. Birdsey, Timothy J. Gay

Timothy J. Gay Publications

We have investigated collisions between transversely polarized electrons and Ar, in which the Ar is simultaneously ionized and excited to the Ar⁺*[3p⁴(⁺D)4p] states. The Stokes parameters of the fluorescence emitted in the following transitions was measured: (⁺D)4s ²D/2−(¹D)4p ²F7/2 (461.0 nm), (¹D)4s ²D5/2 −(¹D)4p ²F5/2 (463.7 nm), (¹P)3d ²D5/2−(¹D)4p ²D5/2 (448.2 nm), and ( …

Computation Of Electron-Impact K-Shell Ionization Cross Sections Of Atoms, M A. Uddin, Abul Kalam Fazlul Haque, M Masum Billah, A K. Basak, Khondkar R. Karim, B C. Saha

Faculty publications – Physics

The total cross sections of electron impact single K-shell ionization of atomic targets, with a wide range of atomic numbers from Z=6-50, are evaluated in the energy range up to about 10 MeV employing the recently proposed modified version of the improved binary-encounter dipole (RQIBED) model [Uddin , Phys. Rev. A 70, 032706 (2004)], which incorporates the ionic and relativistic effects. The experimental cross sections for all targets are reproduced satisfactorily even in the relativistic energies using fixed generic values of the two parameters in the RQIBED model. The relativistic effect is found to be significant in all targets except …

Angular Momentum Partitioning And The Subshell Multipole Moments In Impulsively Excited Argon Ions, H. M. Al-Khateeb, B. G. Birdsey, Timothy J. Gay

Timothy J. Gay Publications

We have investigated collisions between transversely polarized electrons and Ar, in which the Ar is simultaneously ionized and excited to the Ar⁺*[3p⁴(⁺D)4p] states. The Stokes parameters of the fluorescence emitted in the following transitions was measured: (⁺D)4s ²D_5/2−(¹D)4p ²F_7/2 (461.0 nm), (¹D)4s ²D_5/2 −(¹D)4p ²F_5/2 (463.7 nm), (¹P)3d ²D5_5/2−(¹D)4p ²D_5/2 (448.2 …

Self-Consistent Dynamic Models Of Steady Ionization Fronts. I. Weak-D And Weak-R Fronts, W. J. Henney, S. J. Arthur, R. J. R. Williams, Gary J. Ferland

Physics and Astronomy Faculty Publications

We present a method for including steady state gas flows in the plasma physics code Cloudy, which was previously restricted to modeling static configurations. The numerical algorithms are described in detail, together with an example application to plane-parallel ionization-bounded H II regions. As well as providing the foundation for future applications to more complex flows, we find the following specific results regarding the effect of advection on ionization fronts in H II regions: (1) Significant direct effects of advection on the global emission properties occur only when the ionization parameter is lower than is typical for H II regions. For …

Afci Quarterly Input – Unlv January Through March, 2005, Harry Reid Center For Environmental Studies. Nuclear Science And Technology Division

Transmutation Research Program Reports (TRP)

Quarterly report highlighting research projects and activities of the Transmutation Research Program at the Nuclear Science & Technology Division, Harry Reid Research Center.

The University of Nevada, Las Vegas supports the AFCI through research and development of technologies for economic and environmentally sound refinement of spent nuclear fuel. The UNLV program has four components: infrastructure, international collaboration, student-based research, and management and program support.

Dissolution, Reactor, And Environmental Behavior Of Zro2-Mgo Inert Fuel Matrix: Quarterly Report, January 2005 To March 2005, Earl Wolfram, Thomas Hartmann, Kenneth Czerwinski

Fuels Campaign (TRP)

This project will examine inert matrix fuels containing ZrO₂ and MgO as the inert matrix, with the relative amount of MgO varied from 30% to 70% in ZrO₂. Reactor physics calculations will be used to examine suitable quantities of burnable poisons from the candidate elements Gd, Er, or Hf with reactor grade Pu providing the fissile component, with up to 10% of ²³⁹Pu. Ceramics will be synthesized and characterized based on the reactor physics results. The solubility the fuel ceramics, in reactor conditions, reprocessing conditions, and repository conditions, will be investigated in a manner to provide …

Angular Momentum Partitioning And The Subshell Multipole Moments In Impulsively Excited Argon Ions, H. M. Al-Khateeb, B. G. Birdsey, Timothy J. Gay

Timothy J. Gay Publications

We have investigated collisions between transversely polarized electrons and Ar, in which the Ar is simultaneously ionized and excited to the Ar⁺*[3p⁴(⁺D)4p] states. The Stokes parameters of the fluorescence emitted in the following transitions was measured: (⁺D)4s ²D_5/2−(¹D)4p ²F_7/2 (461.0 nm), (¹D)4s ²D_5/2 −(¹D)4p ²F_5/2 (463.7 nm), (¹P)3d ²D_5/2−(¹D)4p ²D_5/2 (448.2 nm), …

Daytime Detection Of Space Objects, Alistair D. Funge

Theses and Dissertations

Space Situational Awareness (SSA) requires repeated object updates for orbit accuracy. Detection of unknown objects is critical. A daytime model was developed that evaluated sun flares and assessed thermal emissions from space objects. Iridium satellites generate predictable sun glints. These were used as a model baseline for daytime detections. Flares and space object thermal emissions were examined for daytime detection. A variety of geometric, material and atmospheric characteristics affected this daytime detection capability. In a photon noise limited mode, simulated Iridium flares were detected. The peak Signal-to- Noise Ratios (SNR) were 6.05e18, 9.63e5, and 1.65e7 for the nighttime, daytime and …

Detection Of Bacillus Spores By Aptamer Selectivity Using Atomic Force Microscopy, Nina M. Houtkooper

Theses and Dissertations

The anthrax attack of Oct 2001 demonstrates the need for a rapid detector for spores of Bacillus anthracis (BA). Current technology requires cultures of BA to be grown for 24 hours. Using aptamers, a type of nucleic acid ligand selective for a target molecule, to select BA spores for measurement without culturing is a possible solution for quicker detection. An aptamer having a specially selected structure is expected to selectively bind to the surface of its target spore, separating it from other material. An atomic force microscopy (AFM) method was developed to test this selectivity. Aptamers having structure selected to …

Optical Investigation Of Transition Metal Implanted Wide Band Gap Semiconductors, Brian P. Feller

Theses and Dissertations

Thin films of GaN, Al_0.1Ga_0.9N, and ZnO were implanted with Cr, Mn, and nickel Ni to produce dilute magnetic semiconductors. Optical and magnetic techniques were used to evaluate crystal structure restoration and coercive field strength as a function of implant species and annealing temperature. Maximum crystal restoration was obtained for Al_0.1Ga_0.9N after annealing at 675 °C; for Cr implanted p-GaN after annealing at 750 °C; for Mn or Ni implanted p-GaN after annealing at 675 °C; for Cr implanted ZnO after annealing at 700 °C; for Mn implanted ZnO after annealing at …

Lethality Of Bacillus Anthracis Spores Due To Short Duration Heating Measured Using Infrared Spectroscopy, Kristina M. Goetz

Theses and Dissertations

There are a number of analytical and semi-empirical models that describe the behavior of particulate matter in the atmosphere. Many of these require modification for all types of weather, dry versus wet deposition, and overall effects can be quite non-linear. Rainfall (rate, drop size, etc.), snowfall (rate, flake size, etc.), humidity, pressure, temperature, and combination of these greatly affect particle settling and washout rates. To that end, a method for tracking released constituents using the Regional Atmospheric Modeling System (RAMS) microphysics package is developed by modifying one of the hydrometeor categories (hail) in the microphysics package. The RAMS microphysics package …

Classification Of Battlespace Detonations From Temporally Resolved Mutli-Band Imagery And Mid-Infrared Spectra, Anthony N. Dills

Theses and Dissertations

The classification of battlespace detonations, specifically the determination of munitions type and size using temporal and spectral features, has been studied using near-infrared (NIR) and multi-color visible wavelength imagers. Key features from the time dependence of fireball size are identified for discriminating various types and sizes of detonation flashes. The five classes include three weights of trinitrotoluene (TNT) and two weights of an enhanced mixture, all of which are uncased and detonated with 10% C4. Using Fisher linear discriminant techniques, features are projected onto a line such that the projected points are maximally clustered for the different classes of detonations. …

Deep Level Defects In Electron-Irradiated Aluminum Gallium Nitride Grown By Molecular Beam Epitaxy, Michael R. Hogsed

Theses and Dissertations

Aluminum gallium nitride (AlGaN)-based devices are attractive candidates for integration into future Air Force communication and sensor platforms, including those that must operate in harsh radiation environments. In this study, the electrical and optical properties of 1.0 MeV electron irradiated n-Al_xGa_1-xN are characterized for aluminum mole fraction x = 0.0 to 0.3 using deep level transient spectroscopy (DLTS), temperature-dependent Hall, and cathodoluminescence (CL) measurements. Following irradiation of the AlGaN, it is found that four different electron traps are created, having energy levels within 0.4 eV below the conduction band edge. Three of these traps correspond to …

Positronium Formation In Positron-Li And Positron-Na Collisions At Low Energies, Anh-Thu Le, M. W. J. Bromley, C. D. Lin

Physics Faculty Research & Creative Works

We present the positronium formation cross sections for a positron colliding with lithium and sodium for the collision energies from 0.01 eV up to 20 eV by the hyperspherical close-coupling method. For Li, our results agree with the experimental data and with other calculations. Our results for Na remain in agreement with previous close-coupling calculations, but do not support the latest experimental data for Na below 1 eV. To validate our model potentials and method in the low-energy regime, the binding energies of positronic lithium and positronic sodium as well as the s-wave scattering lengths for positronium scattering from Li⁺ …

Doubly Differential Cross Sections For Single And Multiple Ionization Of Ne By Electron Impact, Antonio C. Santos, Ahmad Hasan, Robert D. Dubois

Physics Faculty Research & Creative Works

We present doubly differential cross sections for single and multiple ionization of the outer shell of neon by 750 eV electron impact. The distinction between single and multiple ionization was achieved by performing a charge state analysis of the recoil ions in coincidence with forward scattered, energy analyzed electrons. By a comparison to photon impact data, the contribution of the second-order double ionization mechanism is estimated and found to be neglible at this impact energy. Following a similar procedure adopted by J. A. R. Samson [Phys. Rev. Lett. 65, 2861 (1990)], the importance of the first-order TS-1 double ionization mechanism …

The Electronic Structure Of Oriented Poly [2-Methoxy-5-(2’-Ethyl-Hexyloxy)-1,4-Phenylene-Vinylene], D.K. Chambers, S. Karanam, D. Qi, Sandra Zivanovic Selmic, Yaroslav B. Losovyj, Luis G. Rosa, Peter A. Dowben

Peter Dowben Publications

Poly[2-methoxy-5-(2’-ethyl-hexyloxy)-1,4-phenylene-vinylene] (MEH-PPV) adopts a preferential orientation on indium tin oxide. Although the basic building block of this polymer provides a negligible overall point-group symmetry, the polymer MEH-PPV packs with sufficient order to exhibit band structure. The polymer is fragile with bond cleavage evident following both argon-ion impact and ultraviolet radiation, but annealing leads to the restoration of much of the bond order.

Modeling The Infrared Intensity Of A Large Commercial Aircraft, Ruben Martinez

Theses and Dissertations

Measuring the infrared signature of large civilian aircraft has become increasingly important due to the proliferation of man-portable air defense systems (MANPADS) and the increasing threat of their use by terrorists. Because of the range of these shoulder-fired weapons, most aircraft flying over 20,000 feet are safe from the threat; however, aircraft taking-off or landing are extremely vulnerable. A radiometric model was developed to simulate a large commercial aircraft’s infrared intensity during these two critical phases of flight. The radiometric model was largely based on the dimensions of a Boeing 747-400 aircraft. It is capable of simulating elevation angles between …

Search For The Flavor-Changing Neutral Current Decay BS0 → Μ+Μ- In Pp̅ Collisions At √S = 1.96 Tev With The D0 Detector, V. M. Abazov, Gregory R. Snow, D0 Collaboration

Gregory Snow Publications

We present the results of a search for the flavor-changing neutral current decay B_s⁰ → μ⁺μ^- using a data set with integrated luminosity of 240 pb^-1 of pp̅ collisions at √s = 1.96 TeV collected with the D0 detector in run II of the Fermilab Tevatron collider.We find the upper limit on the branching fraction to be Ɓ(B_s⁰ → μ⁺μ^-) ≤ 5.0 x 10^-7 at the 95% C.L. assuming no contributions from the decay B_d⁰ → μ⁺μ^- in the signal …

Measurement Of The W Boson Polarization In Top Decay At Cdf At Sqrt(S)=1.8 Tev, Darin Acosta, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

The polarization of the W boson in t→Wb decay is unambiguously predicted by the standard model of electroweak interactions and is a powerful test of our understanding of the tWb vertex. We measure this polarization from the invariant mass of the b quark from t→Wb and the lepton from W→lν whose momenta measure the W decay angle and direction of motion, respectively. In this paper we present a measurement of the decay rate (f_v+A) of the W produced from the decay of the top quark in the hypothesis of V+A structure of the tWb vertex. …

Γ-Ray Spectroscopy Of 166Hf: X(5) In N > 90?, E. A. Mccutchan, N. V. Zamfir, R. F. Casten, M. A. Caprio, H. Ai, H. Amro, C. W. Beausang, A. A. Hecht, D. A. Meyer, J. J. Ressler

Physics Faculty Publications

Excited states in ¹⁶⁶Hf were populated in the β+/∈ decay of ¹⁶⁶Ta and studied through off-beam γ –ray spectroscopy at the Yale moving tape collector. New coincidence data found no support for two previously reported excited 0⁺ states and led to a substantially revised level scheme. Similarities between the revised level scheme of ¹⁶⁶Hf and the X(5) critical point symmetry are discussed, and the extent of X(5) behavior in this mass region is explored through the W and Os isotopes. Among X(5) candidates with N > 90, good agreement is observed for most energies and …

Linking Physics And Algorithms In The Random-Field Ising Model, Alan Middleton, Jan H. Meinke

Physics - All Scholarship

The energy landscape for the random-field Ising model (RFIM) is complex, yet algorithms such as the push-relabel algorithm exist for computing the exact ground state of an RFIM sample in time polynomial in the sample volume. Simulations were carried out to investigate the scaling properties of the push-relabel algorithm. The time evolution of the algorithm was studied along with the statistics of an auxiliary potential field. At very small random fields, the algorithm dynamics are closely related to the dynamics of two-species annihilation, consistent with fractal statistics for the distribution of minima in the potential (``height''). For $d=1,2$, a correlation …

Search For Anomalous Production Of Diphoton Events With Missing Transverse Energy At Cdf And Limits On Gauge-Mediated Supersymmetry-Breaking Models, Darin Acosta, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We present the results of a search for anomalous production of diphoton events with large missing transverse energy using the Collider Detector at Fermilab. In 202 pb^-1 of pp̅ collisions at √s =1.96 TeV we observe no candidate events, with an expected standard model background of 0.27±0.07(stat)±0.10(syst) events. The results exclude a lightest chargino of mass less than 167 GeV/c², and lightest neutralino of mass less than 93 GeV/c² at 95% C.L. in a gauge-mediated supersymmetry-breaking model with a light gravitino.

Open Charm Yields In D+Au Collisions At √SNn = 200 Gev, Star Collaboration, T.D. Gutierrez

Physics

Midrapidity open charm spectra from direct reconstruction of D⁰(D⁰)→K^∓π^± in d+Au collisions and indirect electron-positron measurements via charm semileptonic decays in p+p and d+Au collisions at √s_NN=200  GeV are reported. The D⁰(D⁰) spectrum covers a transverse momentum (p_T) range of 0.1T<3  GeV/c, whereas the electron spectra cover a range of 1T<4  GeV/c. The electron spectra show approximate binary collision scaling between p+p and d+Au collisions. From these two independent analyses, the differential cross section per nucleon-nucleon binary interaction at midrapidity for open charm production from d+Au collisions at BNL RHIC is dσ^NN_c¯c/dy=0.30±0.04(stat)±0.09(syst)   mb. The results are compared to theoretical calculations. Implications for charmonium results in A+A collisions are discussed.