Digital Commons Network^™

Double Diffraction Dissociation At The Fermilab Tevatron Collider, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We present results from a measurement of double diffraction dissociation in p̅p collisions at the Fermilab Tevatron collider. The production cross section for events with a central pseudorapidity gap of width Δη⁰ > 3 (overlapping η=0) is found to be 4.43±0.02(stat) ± 1.18(syst) mb [3.42 ± 0.01(stat) ± 1.09(syst) mb] at √s=1800[630] GeV. Our results are compared with previous measurements and with predictions based on Regge theory and factorization.

Observation Of Orbitally Excited B Mesons In Pp̅ Collisions At √S =1.8  Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We measure the relative rate of production of orbitally excited (L=1) states of B mesons (B**) by observing their decays into B π ^±. We reconstruct B mesons through semileptonic decay channels using data collected in pp̅ collisions at √s =1.8 TeV. The fraction of light B mesons that are produced as L=1B** states is measured to be 0.28±0.06(stat) ±0.03(syst). We also measure the collective mass of the B** states, and quantify the result by quoting the (model-dependent) mass of the lowest B** state to be m (B₁)=5.71 ±0.02 GeV/ …

A Statistical Study Of Transient Event Motion At Geosynchronous Orbit, Jeff Sanny, David Berube, D. G. Sibeck

Physics Faculty Works

The geosynchronous GOES 5 and GOES 6 satellites frequently observe transient events marked by magnetic field strength increases and bipolar magnetic field signatures lasting several minutes. In this study we report a survey of 87 events observed simultaneously by both GOES spacecraft (for a total of 174 individual observations) from August to December 1984. Events detected in the prenoon sector outnumbered those in the postnoon sector by about a 3 to 1 ratio. The distribution of the events versus local time exhibited a significant prenoon peak like the distribution of magnetic impulse events observed in high-latitude ground magnetometers. A cross-correlation …

Monte Carlo Studies Of Mott Scattering Asymmetries From Gold Foils, M. A. Khakoo, D. Roundy, C. Hicks, N. Margolis, E. Yeung, A. W. Ross, Timothy J. Gay

Timothy J. Gay Publications

We present the results of a series of model Monte Carlo calculations of the scattering of spin-polarized electrons from gold foil targets. Our calculations examine the behavior of the left-right scattering asymmetry A as a function of various parameters conventionally used in extrapolation of the left-right asymmetry to single atom and/or elastic scattering conditions. These parameters include target thickness, scattered count rate, and the maximum energy that an electron can have lost in the target and still be detected. Data are obtained at incident electron energies of 10–120 keV, with detector-subtended half-cone angles of 5°, 10°, and 20°, and gold …

Computational Fluid Dynamic Study Of A Nascar Winston Cup Series Race Car, Terry L. Meek Jr.

Mechanical & Aerospace Engineering Theses & Dissertations

Since the goal of NASCAR racing is to win and since drag is a force the vehicle must overcome, a thorough understanding of the drag generating airflow around and through the automobile is greatly desired. The external airflow contributes to most of the drag that a car experiences and most of the downforce the vehicle produces. Therefore, an estimate of the vehicle's performance may be evaluated using a computational aerodynamics model. This thesis presents a computational fluid dynamic (CFD) analysis of a NASCAR Winston Cup series race car to investigate the salient flow characteristics.

Before a computational analysis could be …

Poynting's Theorem And Luminal Total Energy Transport In Passive Dielectric Media, Scott Glasgow, Michael Ware, Justin Peatross

Faculty Publications

Without approximation the energy density in Poynting's theorem for the generally dispersive and passive dielectric medium is demonstrated to be a system total dynamical energy density. Thus the density in Poynting's theorem is a conserved form that by virtue of its positive definiteness prescribes important qualitative and quantitative features of the medium-field dynamics by rendering the system dynamically closed. This fully three-dimensional result, applicable to anisotropic and inhomogeneous media, is model independent, relying solely on the complex-analytic consequences of causality and passivity. As direct applications of this result, we show 1 that a causal medium responds to a virtual, instantaneous …

Threshold Effects On Angular Distributions For Multiphoton Detachment By Intense Elliptically Polarized Light, Bogdan Borca, M.V. Frolov, N. L. Manakov, Anthony F. Starace

Anthony F. Starace Publications

Unusual threshold effects are found theoretically in the frequency and intensity dependence of angular distributions produced by an elliptically polarized laser as well as in the elliptic dichroism parameter, which measures the asymmetry of the angular distribution.

Measurement Of DΣ/Dm And Forward-Backward Charge Asymmetry For High-Mass Drell-Yan E+E- Pairs From Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We report on a measurement of the mass dependence of the forward-backward charge asymmetry, A_FB, and production cross section dσ /dM for e⁺e^- pairs with mass M_ee> 40 GeV/c². The data sample consists of 108 pb^-1 of pp̅ collisions at √s= 1.8 TeV taken by the Collider Detector at Fermilab during 1992–1995. The measured asymmetry and dσ/dM are compared with the predictions of the standard model and a model with an extra Z′ gauge boson.

Three-Jet Production In Diffractive Deep Inelastic Scattering At Hera, S. Chekanov, M. Derrick, D. Krakauer, S. Magill, B. Musgrave, A. Pellegrino, J. Repond, R. Yoshida, Margarita C. K. Mattingly, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, P. Giusti, G. Iacobucci, G. Levi, A. Margotti, T. Massam, R. Nania, F. Palmonari, A. Pesci, G. Sartorelli

Faculty Publications

Three-jet production in the reaction ep → eXp has been studied with the ZEUS detector at HERA using an integrated luminosity of 42.74 pb-1.The data were measured in the kinematic region 5 < Q2 < 100 GeV2, 200 < W < 250 GeV and 23 < MX < 40 GeV. The diffractive signal was selected by requiring a large rapidity gap in the outgoing proton direction. Jets were reconstructed in the centre-of-mass system of X using the exclusive kT-algorithm. A sample of three-jet events in diffraction has been identified. Differential cross sections were measured as a function of the jet pseudorapidity and jet transverse momentum with respect to the virtual photon-pomeron axis. The jets going in the pomeron direction are broader than those going in the virtual-photon direction. This is consistent with models predicting that gluons are predominantly produced in the pomeron direction and quarks in the virtual-photon direction. © 2001 Elsevier Science B.V. All rights reserved.

Measurement Of The Top Quark PT Distribution, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We have measured the p_T distribution of top quarks that are pair produced in pp̅ collisions at √s=1.8 TeV using a sample of tt̅ decays in which we observe a single high-p_T charged lepton, a neutrino, and four or more jets. We use a likelihood technique that corrects for the experimental bias introduced due to event reconstruction and detector resolution effects. The observed distribution is consistent with the standard model prediction. We use these data to place limits on the production of high-p_T top quarks suggested in some models of anomalous top quark pair production.

Mev Magnetosheath Ions Energized At The Bow Shock, S. Chang, J. D. Scudder, K. Kudela, Harlan E. Spence, J. F. Fennell, R. P. Lepping, R. P. Lin, C. T. Russell

Physics & Astronomy

A causal relationship between midlatitude magnetosheath energetic ions and bow shock magnetic geometry was previously established for ion energy up to 200 keV e−1 for the May 4, 1998, storm event. This study demonstrates that magnetosheath ions with energies above 200 keV up to 1 MeV simply extend the ion spectrum to form a power law tail. Results of cross-correlation analysis suggest that these ions also come directly from the quasi-parallel bow shock, not the magnetosphere. This is confirmed by a comparison of energetic ion fluxes simultaneously measured in the magnetosheath and at the quasi-parallel bow shock when both regions …

On Misorientation Distribution Evolution During Anisotropic Grain Growth, Elizabeth A. Holm, Gregory N. Hassold, Mark A. Miodownik

Physics Publications

In order to study the development of texture and boundary character during annealing, three-dimensional grain crystallography and crystallographically mediated grain boundary properties were incorporated into a finite temperature Monte Carlo model for grain growth. Randomly textured microstructures evolve normally, with growth exponent n=0.96. While texture remains random, the steady-state boundary misorientation distribution favors low-angle boundaries. To first order, low-angle boundaries increase by lengthening, not by proliferating. In contrast, microstructures with a strong single-component texture develop four-grain junctions and highly curved grain boundaries, which alter evolution. The boundary misorientation distribution narrows and shifts to low angles, and no steady state …

Comment On “Photodetachment In Combined Static And Dynamic Electric Fields”`, Ilya I. Fabrikant, M.V. Frolov, N. L. Manakov, Anthony F. Starace

Anthony F. Starace Publications

The theoretical analysis of C. Rangan and A. R. P. Rau [Phys. Rev. A 61, 033405 (2000)] on the process of photodetachment of H^- in a strong static electric field, which calls into question the predictions of B. Gao and A. F. Starace [Phys. Rev. A 42, 5580 (1990)] and also of M. Q. Bao et al. [Phys. Rev. A 58, 411 (1998)], is shown in this Comment to be incorrect. First, we point out that a number of assumptions of Rangan and Rau’s analysis rest on tenuous theoretical grounds. Second, we adduce two completely independent and different …

Thermal Activation Between Landau Levels In The Organic Superconductor Β″-(Bedt-Ttf)2sf5ch2cf2so3, Gary L. Gard, M. S. Nam, A. Ardavan, J. A. Symington, J. Singleton, N. Harrison, C. H. Mielke, J. A. Schlueter, Rolf Walter Winter

Chemistry Faculty Publications and Presentations

We show that Shubnikov–de Haas oscillations in the interlayer resistivity of the organic superconductor β″-(BEDT-TTF)₂SF₅CH₂CF₂SO₃ become very pronounced in magnetic fields ~60T. The conductivity minima exhibit thermally activated behavior that can be explained simply by the presence of a Landau gap, with the quasi-one-dimensional Fermi surface sheets contributing negligibly to the conductivity. This observation, together with complete suppression of chemical potential oscillations, is consistent with an incommensurate nesting instability of the quasi-one-dimensional sheets.

The Blazhko Effect Of The Rr Lyrae Star Dr Andromedae, Kevin M. Lee, Edward G. Schmidt

Edward Schmidt Publications

We have obtained 551 new V and R observations of the RR Lyrae star DR Andromedae. Our data set is consistent with a primary period of 0.563118 days; however, the light curve of DR And cannot be well described by a single period. We conclude that DR And demonstrates the Blazhko effect with a Blazhko period of approximately 57.5 days.

Measurement Of The W Boson Mass With The Collider Detector At Fermilab, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We present a measurement of the W boson mass using data collected with the CDF detector during the 1994–1995 collider run at the Fermilab Tevatron. A fit to the transverse mass spectrum of a sample of 30115 W→eν events recorded in an integrated luminosity of 84 pb^-1 gives a mass M_w=80.473±0.065(stat) ±0.092(syst) GeVc². A fit to the transverse mass spectrum of a sample of 14740 W→μν events from 80 pb^-1 gives a mass M_w=80.465±0.100(stat) ±0.103(syst) GeV/c². The dominant contributions to the systematic uncertainties are the …

Structural, Transport And Magnetic Studies Of Perovskite Bi1-X Cax Mn O3, Hyungje Woo

Dissertations

This dissertation presents an investigation of the fundamental physics of the perovskite system Bi_1-xCa_xMn0₃. This material belongs to a group of simple perovskites called the manganites which are of technological importance for magnetic device applications as read-head sensors.

The Bi_1-xCa_xMnO₃ system is known to exhibit charge ordering (and high sensitivity to magnetic fields) for a much broader range of x than the well-characterized La_1-xCa_xMnO₃ system. However, the properties of Bi_1-xCa_xMnO₃ over the entire doping range are not well understood. …

Detection Of Vapor Phase Mercury Species By Laser Fluorescence Methods, Xiaomei Tong

Dissertations

Elemental and compound mercury are often both volatile and air stable. Several mercury species emissions have been identified in off-gases from industrial processes. The high toxicity of mercury species and the presence of mercury species in municipal waste and coal have prompted a demand for a cost-effective, accurate, and rugged technique for real-time, continuous detection of mercury species vapors. Real-time, continuous emission measurements are important for process control, monitoring, and remediation. At present, there is no commercial continuous emission monitoring (CEM) technique or instrumentation to reliably monitor volatile mercury species emissions from industrial stacks. Conventional measurement methods, such as cold …

Renormalization Of The Inverse Square Potential, Horacio E. Camblong

Physics and Astronomy

The quantum-mechanical D-dimensional inverse square potential is analyzed using field-theoretic renormalization techniques. A solution is presented for both the bound-state and scattering sectors of the theory using cutoff and dimensional regularization. In the renormalized version of the theory, there is a strong-coupling regime where quantum-mechanical breaking of scale symmetry takes place through dimensional transmutation, with the creation of a single bound state and of an energy-dependent s-wave scattering matrix element.

Static-Electric-Field Behavior In Negative Ion Detachment By An Intense, High-Frequency Laser Field, M. V. Frolov, N. L. Manakov, B. Borca, Anthony F. Starace

Anthony F. Starace Publications

Based upon the exact numerical solution of the complex quasienergy problem for a 3-dimensional short-range potential as well as upon analytical evaluations, we demonstrate for any finite frequency ω that the action of an ultra-intense laser field (with electric vector F(ωt)) on a weakly bound atomic system may be described by the cycle-averaging of results for an instantaneous static electric field of strength |F(ωt)|.

Electric Field Autocorrelation Functions For Beginning Multiple Rayleigh Scattering, James A. Lock

Physics Faculty Publications

The polarization-resolved electric field autocorrelation function for p-order scattering was derived from the order-of-scattering solution of the exact equations for electromagnetic multiple Rayleigh scattering and was calculated for 2 less than or equal to p less than or equal to 6 for particles undergoing diffusive motion in an idealized sample cell. It was found that the polarization-channel and the scattering-angle dependence of the p-order autocorrelation function approximately decoupled from the delay-time dependence for p greater than or similar to 3. The polarization-channel and the scattering-angle dependence were analytically calculated, and the delay-time dependence was analytically approximated. The resulting analytical model …

Charge Transfer And X-Ray Emission Reactions Involving Highly Charged Ions And Neutral Hydrogen, J. A. Perez, Ronald E. Olson, P. Beiersdorfer

Physics Faculty Research & Creative Works

The electron capture from hydrogen by highly charged-bare ions was studied using a three-body classical trajectory Monte Carlo (CTMC) method. The state-selective capture cross sections, calculated for a wide range of collision energies, were used to estimate x-ray emission cross sections. The capture process produced excited hydrogen-like ions and captured majority of electrons into one or two dopant states at low collision energies. The calculations predicted a large increase in the fraction of prompt x-rays produced with the lowering of the collision energy. The analysis suggested that ionization potential change for each collision and multiple capture played significant role in …

Measurement Of The Inclusive Jet Cross Section In Pp̅ Collisions At √S =1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We present results from the measurement of the inclusive jet cross section for jet transverse energies from 40 to 465 GeV in the pseudorapidity range 0.1<|η|-1 of data collected by the CDF Collaboration at the Fermilab Tevatron collider. The data are consistent with previously published results. The data are also consistent with QCD predictions given the flexibility allowed from current knowledge of the proton parton distributions. We develop a new procedure for ranking the agreement of the parton distributions with data and find that the data are best described by QCD predictions using the parton distribution functions which have a large gluon contribution at high E_T (CTEQ4HJ).

Statistics And Supermetallicity: The Metallicity Of Ngc 6791, B. J. Taylor

Faculty Publications

For the old galactic cluster NGC 6791, Peterson & Green (1998a) and Chaboyer et al. (1999) have found that [Fe/H] approximately + 0.4 dex. A second look at that conclusion is taken in this paper. Zero-point problems are reviewed for a high-dispersion analysis done by Peterson & Green, and it is found that accidental errors have not been determined rigorously for the results of that analysis. It is also noted that in a color-magnitude analysis performed by Chaboyer et al., the important metallicity range between 0.0 and + 0.3 dex is not explored and hence is not ruled out. Moreover, …

Search For Heavy Particles Decaying Into Electron-Positron Pairs In Pp̅ Collisions, V. M. Abazov, Gregory R. Snow, D0 Collaboration

Gregory Snow Publications

We present results of searches for technirho (ρ_T), techniomega (ω_T), and Z ′ particles, using the decay channels ρ_T, ω_T, Z ′ → ℯ⁺ℯ^-. The search is based on 124.8 pb^-1 of data collected by the D0 detector at the Fermilab Tevatron during 1992–1996. In the absence of a signal, we set 95% C.L. upper limits on the cross sections for the processes pp̅ → ρ_T, ω_T, Z ′ → ℯ⁺ℯ^- as a function of the mass of the decaying …

Yang-Lee Edge Singularities From Experimental High Field Magnetization Data, Christian Binek

Christian Binek Publications

The isothermal magnetization m(H) of the metamagnet FeCl2 is measured in axial magnetic fields 0≤µ0Ha≤12 T at temperatures 34≤T≤53 K above the Néel temperature, where the system is essentially a two-dimensional Ising ferromagnet. The analysis of the data indicates experimental accessibility of the critical exponent µ of the Yang-Lee edge singularities. They manifest themselves in divergences of the density functions g(θ), which quantify the distribution of the zeros of the partition function on the Lee-Yang unit circle in the complex plane. In accordance with the hypothesis of universality, a critical exponent close to the theoretical prediction for the two-dimensional Ising …

X-Ray Photoelectron Spectroscopy (Xps) And Magnetization Studies Of Iron–Vanadium Phosphate Glasses, M. A. Salim, G. D. Khattak, Petru S. Fodor, Lowell E. Wenger

Physics Faculty Publications

Vanadium phosphate glasses containing Fe2O3 with the chemical composition [(Fe2O3)x(V2O5)0.6−x(P2O5)0.4], where x=0.00, 0.10, 0.20, 0.25 and 0.30, have been prepared and investigated by X-ray photoelectron spectroscopy (XPS) and magnetic susceptibility measurements. The core level binding energies of V 2p, Fe 2p, P 2p and P 2s in the Fe2O3–vanadium phosphate glasses have been measured and shifts from the corresponding binding energies measured for V2O5, Fe2O3 and P2O5 powders are accounted for by changes in the next-nearest neighbor environment of these atoms in the P4O10 local structure. The O 1s spectra for the glasses are single, symmetric peaks arising from nearly …

Yang-Lee Edge Singularities Determined From Experimental High-Field Magnetization Data, Christian Binek, Wolfgang Kleemann, H. Aruga Katori

Christian Binek Publications

The isothermal magnetization m (H) of the metamagnet FeCl₂ is measured in axial magnetic fields 0 ≤ μ₀H_a ≤ 12 T at temperatures 34 ≤ T ≤ 53 K above the Néel temperature, where the system is essentially a two-dimensional Ising ferromagnet. The analysis of the data indicates experimental accessibility of the critical exponent μ of the Yang-Lee edge singularities. They manifest themselves in divergences of the density functions g(θ), which quantify the distribution of the zeros of the partition function on the Lee-Yang unit circle in the complex plane. In accordance with …

Critique Of The Wigner Tunneling Speed And A Proposed Alternative, P Krekora, Q Su, Rainer Grobe

Faculty publications – Physics

In the context of superluminal propagation of wave packets through potential barriers, the tunneling speed is usually characterized by the Wigner velocity. We propose an alternative speed that takes into account the interference between the incoming and the reflected waves and leads to a better estimation of arrival time for a wave packet entering the tunneling region. This arrival time is derived by an extrapolation from inside the barrier. The analytical theory is based on the stationary phase approximation whose validity is justified by a comparison with the numerical solution of the time-dependent Dirac equation.

Predicted Maximum Mobility In Bulk Gan, David C. Look, J. R. Sizelove

Physics Faculty Publications

A 300 K bulk (three-dimensional) mobility of 1245 cm²/V s has been measured in free-standing GaN. Temperature-dependent Hall-effect data on this particular sample are fitted to obtain unknown lattice-scattering parameters, as well as shallow donor (N_D) and acceptor (N_A) concentrations, which are N_D = 6.7×10¹⁵ and N_A = 1.7×10¹⁵ cm⁻³. Realistic values of the maximum mobility attainable in bulk GaN are then obtained by assuming two-orders-of-magnitude lower values of N_D and N_A, leading to a maximum 300 K mobility of 1350 cm^{2 …}