Physical Sciences and Mathematics Commons^™

Criss-Crossing Laser Beams Zoom Electrons Along, P. Zhang, N. Saleh, Shouyuan Chen, Z.M. Sheng, Donald P. Umstadter

Donald Umstadter Publications

Crossing two high-intensity laser beams in a plasma (a collection of charged particles) can have some interesting effects. In a recent experiment performed by researchers at the University of Michigan and the Institute of Physics in China, energy from a higher-power laser pulse was transferred to a lower-power laser pulse. The lower-power pulse had been accelerating electrons with its "wakefield" (like a wave accelerating a surfer). The extra energy to this lower-power pulse enhanced the electron acceleration and decreased the divergence of the electron beam. These features are desirable for proposed "laser particle accelerators" that would be powered by relatively …

Giant Metamagnetic Moments In A Granular Fecl2-Fe Heterostructure, Sarbeswar Sahoo, Christian Binek, Wolfgang Kleemann

Christian Binek Publications

Giant moments are observed at low temperatures in a granular FeCl₂-Fe heterostructure owing to a local metamagnetic transformation of the antiferromagnetic (AF) FeCl₂ matrix due to dipolar interactions. A model of metamagnetically (MM) "dressed" single-domain Fe particles is suggested to explain the observations. These include polydispersive ac susceptibility induced by AF-MM domain configurations and weak exchange bias due to non-spin-flipped AF crystallites.

Search For The Flavor-Changing Neutral Current Decay D0→Μ +Μ - In Pp̅ Collisions At √S =1.96 Tev, Darin Acosta, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We report on a search for the flavor-changing neutral current decay D⁰→µ⁺µ^- in pp̅ collisions at √s =1.96 TeV using 65 pb^-1 of data collected by the CDF II experiment at the Fermilab Tevatron Collider. A displaced-track trigger selects long-lived D⁰ candidates in the D⁰→µ⁺µ^- search channel, the kinematically similar D⁰→ π⁺ π^- channel used for normalization, the Cabibbo-favored D⁰→ K^-π⁺ channel used to optimize the selection criteria in an unbiased manner, and their charge conjugates. Finding no signal …

Exclusive Electrodisintegration Of Three-Nucleon Systems, Tigran Abrahamyan

FIU Electronic Theses and Dissertations

The purpose of this research was to develop a theory of high-energy exclusive electrodisintegration of three-nucleon systems on the example of 3He(e, e'NN)N reaction with knocked-out nucleon in the final state.

The scattering amplitudes and differential cross section of the reaction were calculated in details within the Generalized Eikonal Approximation(GEA). The manifestly covariant nature of Feynman diagrams derived in GEA allowed us to preserve both the relativistic dynamics and kinematics of the scattering while identifying the low momentum nuclear part of the amplitude with a nonrelativistic nuclear wave function. Numerical calculations of the residual system's total and relative momentum distribution …

Twin-Rainbow Metrology. I. Measurement Of The Thickness Of A Thin Liquid Film Draining Under Gravity, Charles L. Adler, James A. Lock, Ian P. Rafferty, Wayne Hickok

Physics Faculty Publications

We describe twin-rainbow metrology, a new optical technique used to measure the thickness of thin films in a cylindrical geometry. We also present an application of the technique: measurement of the thickness of a Newtonian fluid draining under gravity. We compare these measurements with fluid mechanics models. (C) 2003 Optical Society of America.

Domain Wall Solutions With Abelian Gauge Fields, J. S. Rozowsky, R. R. Volkas, K. C. Wali

Physics - All Scholarship

We study kink (domain wall) solutions in a model consisting of two complex scalar fields coupled to two independent Abelian gauge fields in a Lagrangian that has $U(1)\times U(1)$ gauge plus $\mathbb{Z}_2$ discrete symmetry. We find consistent solutions such that while the U(1) symmetries of the fields are preserved while in their respective vacua, they are broken on the domain wall. The gauge field solutions show that the domain wall is sandwiched between domains with constant magnetic fields.

Long Coherence Times At 300 K For Nitrogen-Vacancy Center Spins In Diamond Grown By Chemical Vapor Deposition, John S. Colton, T. A. Kennedy, J. E. Butler, R. C. Linares, P.J. Doering

Faculty Publications

Electron-spin-echo experiments reveal phase-memory times as long as 58 μs at 300 K for nitrogen-vacancy centers in chemical vapor deposition (CVD) single crystals. The spins were optically polarized and optically detected. Two high-quality CVD samples were studied. From the current results, it is not clear whether these phase-memory times represent a fundamental limit or are limited by an external source of decoherence.

Labview Interface For School-Network Daq Card, Hans Berns, T. H. Burnett, Richard Gran, Graham Wheel, R. Jeffrey Wilkes, Daniel R. Claes, Jared Kite, Gregory R. Snow

Gregory Snow Publications

A low-cost DAQ card has been developed for school-network cosmic ray detector projects, providing digitized data from photomultiplier tubes via a standard serial interface. To facilitate analysis of these data and to provide students with a starting point for custom readout systems, a model interface has been developed using the National Instruments LabVIEW(R) system. This user-friendly interface allows one to initialize the trigger coincidence conditions for data-taking runs and to monitor incoming or pre-recorded data sets with updating singles- and coincidence-rate plots and other user-selectable histograms.

Low-Cost Data Acquisition Card For School-Network Cosmic Ray Detectors, Sten Hansen, Thomas Jordan, Daniel R. Claes, Gregory R. Snow, Hans Berns, T. H. Burnett, Richard Gran, R. Jeffrey Wilkes

Gregory Snow Publications

The Cosmic Ray Observatory Project (CROP) at University of Nebraska/Lincoln and the Washington Area Large-scale Time coincidence Array (WALTA) at University of Washington/Seattle are among several outreach projects siting cosmic-ray detectors at local high schools in cities around North America, to study the origins and interactions of highenergy cosmic rays. In a collaboration between QuarkNet, the outreach program based at Fermilab, CROP, and WALTA, a low-cost data acquisition electronics card has been developed to collect and synchronize the data from each detector site. The cost for each card is under US$500 for parts, functionally replacing much more expensive electronics crates …

Mean Field Theory Of Collective Transport With Phase Slips, Alan Middleton, Karl Saunders, J. M. Schwarz, M. Cristina Marchetti

Physics - All Scholarship

The driven transport of plastic systems in various disordered backgrounds is studied within mean field theory. Plasticity is modeled using non-convex interparticle potentials that allow for phase slips. This theory most naturally describes sliding charge density waves; other applications include flow of colloidal particles or driven magnetic flux vortices in disordered backgrounds. The phase diagrams exhibit generic phases and phase boundaries, though the shapes of the phase boundaries depend on the shape of the disorder potential. The phases are distinguished by their velocity and coherence: the moving phase generically has finite coherence, while pinned states can be coherent or incoherent. …

Measurement Of The Open-Charm Contribution To The Diffractive Proton Structure Function, S. Chekanov, M. Derrick, D. Krakauer, J. H. Loizides, S. Magill, B. Musgrave, 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, A. Margotti, R. Nania, F. Palmonari, A. Pesci, G. Sartorelli, A. Zichichi, G. Aghuzumtsyan

Faculty Publications

Production of D*±(2010) mesons in diffractive deep inelastic scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 82 pb-1. Diffractive events were identified by the presence of a large rapidity gap in the final state. Differential cross sections have been measured in the kinematic region 1.5

Mode Structure Of Diffusive Transport In Hydroxypropylcellulose:Water, George D.J. Phillies, Robert O. Connell, Paul Whitford, Kiril A. Streletzky

Physics Faculty Publications

A systematic analysis of the mode structure of diffusive relaxations in 1 MDa hydroxypropylcellulose(HPC):water is presented. New methods and data include (1) use of integral spectral moments to characterize nonexponential decays, (2) spectra of small probes in concentrated HPC solutions, (3) temperature dependence of the mode structure, and (4) comparison of optical probe spectra and spectra of probe-free polymer solutions. We find that (1) probe and polymer relaxations are in general not the same; (2) the apparent viscometric crossover near ct≈6 g/l is echoed by probe behavior; (3) our HPC solutions have a characteristic dynamic length, namely the 50 nm …

State-To-State Rotational Rate Constants For Co+He: Infrared Double Resonance Measurements And Simulation Of The Data Using The Sapt Theoretical Potential Energy Surface, Tony C. Smith, David A. Hostutler, Gordon D. Hager, Michael C. Heaven, George C. Mcbane

Peer Reviewed Articles

An extensive data set of 54 time-resolved pump-probe measurements was used to examine CO+He rotational energy transfer within the CO v=2 rotational manifold. Rotational levels in the range J_i=2-9 were excited and collisional energy transfer of population to the levels J_f=1-10 was monitored. The resulting data set was analyzed by fitting to numerical solutions of the master equation. State-to-state rate constant matrices were generated using fitting law functions and ab initio theoretical calculations that employed the SAPT potential energy surface of Heijmen et al. [J. Chem. Phys. 107, 9921 (1997)]. Fitting laws based on …

Magnetoresistance In Boron Carbide Junctions, L. Bernard, J. Monson, Andrei Sokolov, Zong-Yuan Liu, C.S. Yang, Peter A. Dowben, Bermard Doudin, A. Harken, P. Welsch, B. W. Robertson

Peter Dowben Publications

Photoemission and electric transport properties of ferromagnet–insulator–ferromagnet junctions with boron carbide (C₂B₁₀) dielectric barrier are presented. Using a non-oxide barrier confidence avoids oxidation of the interfaces with the ferromagnetic layers. Photoemission confirms chemical abruptness of the interface. Magnetoresistance ratios reaching 50% are observed at low temperatures, and large nonlinearity in the current–voltage curves show that impurities in the junctions play a key role. © 2003 American Institute of Physics.

Computer-Controlled In-Class Feedback System For Interactive Lectures, Thomas J. Bensky

Physics

Instructors who wish to implement an interactive lecture style, such as peer instruction, have the need to collect feedback from students in a lecture environment. We present a computer-controlled electronic circuit that allows for quick, rigorous, and accurate measurement and reporting of student feedback in the lecture environment.

Evidence Of The Zn Vacancy Acting As The Dominant Acceptor In N-Type Zno, F. Tuomisto, V. Ranki, K. Saarinen, David C. Look

Physics Faculty Publications

We have used positron annihilation spectroscopy to determine the nature and the concentrations of the open volume defects in as-grown and electron irradiated (E_el=2   MeV, fluence 6×10¹⁷   cm^-2) ZnO samples. The Zn vacancies are identified at concentrations of [V_Zn]≃2×10¹⁵   cm^-3 in the as-grown material and [V_Zn]≃2×10¹⁶   cm^-3 in the irradiated ZnO. These concentrations are in very good agreement with the total acceptor density determined by temperature dependent Hall experiments. Thus, the Zn vacancies are dominant acceptors in both as-grown and irradiated ZnO.

Statistics Of Transmission In One-Dimensional Disordered Systems: Universal Characteristics Of States In The Fluctuation Tails, Lev I. Deych, Mikhail V. Erementchouk, Alexander A. Lisyansky, Alexey Yamilov, Hui Cao

Physics Faculty Research & Creative Works

We numerically study the distribution function of the conductance (transmission) in the one-dimensional tight-binding Anderson and periodic-on-average superlattice models in the region of fluctuation states where single parameter scaling is not valid. We show that the scaling properties of the distribution function depend upon the relation between the system's length L and the length l_s determined by the integral density of states. For long enough systems, L ≫ l_s, the distribution can still be described within a new scaling approach based upon the ratio of the localization length l_loc and l_s. In an intermediate …

Review Of "Liquid Crystals: Fundamentals" By S. Singh, Peter J. Collings

Physics & Astronomy Faculty Works

No abstract provided.

Ecotoxicological Research At Dit, Maria Davoren, Colm O'Dowd, Sharon Ni Shuilleabhain

Articles

The term ecotoxicology first defined by Rene Truhart in 1969, essentially describes the study of the harmful effects of chemicals upon ecosystems.

Test Particle Acceleration In Three-Dimensional Magnetohydrodynamic Turbulence, P. Dmitruk, W. H. Matthaeus, N. Seenu, Michael R. Brown

Physics & Astronomy Faculty Works

We perform numerical experiments of test particle acceleration on turbulent magnetic and electric fields obtained from pseudospectral direct numerical solutions of the compressible three-dimensional MHD equations. We find consistent acceleration of the particles to many times the plasma characteristic (Alfven) speed and extended power laws in the density distribution of energies. Scaling laws of maximum and mean energy of particles with the nominal gyrofrequency and the MHD electric field are observed and a simple estimate is presented.

The Spectra Of Type Ii Cepheids. Ii. The Hα Line In Intermediate-Period Stars, Edward G. Schmidt, Shawn Langan, Kevin M. Lee, Dale Johnston, Peter R. Newman, Stephanie A. Snedden

Edward Schmidt Publications

We present 98 Hα profiles for 21 pulsating variable stars with periods from 3 to 8 days. The strength, depth, and shape of Hα vary throughout the cycles of the stars in a way consistent with the temperature changes. Otherwise, they are quite uniform among all the stars, with a single exception. In FM Del, Hα is weaker and has a smaller central depth than in the other stars. This and the wavelength shifts of the core are attributed to incipient emission. The differential velocity of Hα relative to the metal lines is less than 25 km s^-1 for …

Theoretical Investigation Of The Surface Vibrational Modes In Germanium Nanocrystals, Shang-Fen Ren, Wei Cheng, Peter Y. Yu

Faculty publications – Physics

We have used a microscopic lattice dynamical model to study phonon modes in germanium (Ge) NC with size varying between 47 to 7289 atoms (diametersimilar to6.8 nm). By separating these atoms into bulk and surface atoms we have found that surface modes can exist in Ge NC both at low frequencies (<50>cm(-1)) and at high frequency (similar to260 cm(-1)). The latter mode is a resonant mode which occurs in the "pseudogap" between the acoustic and optical phonon branches in bulk Ge. From the low frequency surface modes we have been able to reconstruct the spheroidal and torsional Lamb modes …

Jet Production In Charged Current Deep Inelastic E+P Scattering At Hera, S. Chekanov, M. Derrick, D. Krakauer, J. H. Loizides, S. Magill, B. Musgrave, 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, A. Margotti, R. Nania, F. Palmonari, A. Pesci, G. Sartorelli, A. Zichichi, G. Aghuzumtsyan

Faculty Publications

The production rates and substructure of jets have been studied in charged current deep inelastic e+p scattering for Q2 > 200 GeV2 with the ZEUS detector at HERA using an integrated luminosity of 110.5 pb-1. Inclusive jet cross sections are presented for jets with transverse energies ETjet > 14 GeV and pseudorapidities in the range -1 < ηjet < 2. Dijet cross sections are presented for events with a jet having ETjet > 14 GeV and a second jet having ETjet > 5 GeV. Measurements of the mean subjet multiplicity, 〈ηsbj〉, of the inclusive jet sample are presented. Predictions based on parton-shower Monte Carlo models and next-to-leading-order QCD calculations are compared to the measurements. The value of αs (MZ), determined …

Net Charge Fluctuations In Au+Au Collisions At √SNn=130 Gev, Star Collaboration, T.D. Gutierrez

Physics

We present the results of charged particle fluctuations measurements in Au+Au collisions at √s_NN=130 GeV using the STAR detector. Dynamical fluctuations measurements are presented for inclusive charged particle multiplicities as well as for identified charged pions, kaons, and protons. The net charge dynamical fluctuations are found to be large and negative providing clear evidence that positive and negative charged particle production is correlated within the pseudorapidity range investigated. Correlations are smaller than expected based on model-dependent predictions for a resonance gas or a quark-gluon gas which undergoes fast hadronization and freeze-out. Qualitative agreement is found with comparable scaled …

New Results From The Cryogenic Dark Matter Search Experiment, D. S. Akerib, J. Alvaro-Dean, M. S. Armel, M. J. Attisha, L. Baudis, D. A. Bauer, A. I. Bolozdynya, P. L. Brink, R. Bunker, Blas Cabrera, D. O. Caldwell, J. P. Castle, C. L. Chang, R. M. Clarke, M. B. Crisler, P. Crushman, A. K. Davies, R. Dixon, D. D. Driscoll, L. Duong, J. Emes, R. Ferril, R. J. Gaitskell, S. R. Golwala, M. Haldeman, J. Hellmig, M. Hennessey, D. Holmgren, M. E. Huber, S. Kamat, M. Kurylowicz, A. Lu, R. Mahapatra, V. Mandic, J. M. Martinis, P. Meunier, N. Mirabolfathi, S. W. Nam, H. Nelson, R. Nelson, R. W. Ogburn, J. Perales, T. A. Perera, M. C. Perillo Isaac, W. Rau, A. Reisetter, R. R. Ross, T. Saab, B. Sadoulet, J. Sander, C. Savage, R. W. Schnee, D. N. Seitz, T. A. Shutt, G. Smith, A. L. Spadafora, J.-P. F. Thompson, A. Tomada, G. Wang, S. Yellin, Betty A. Young

Physics

Using improved Ge and Si detectors, better neutron shielding, and increased counting time, the Cryogenic Dark Matter Search (CDMS) experiment has obtained stricter limits on the cross section of weakly interacting massive particles (WIMPs) elastically scattering from nuclei. Increased discrimination against electromagnetic backgrounds and reduction of the neutron flux confirm WIMP-candidate events previously detected by CDMS were consistent with neutrons and give limits on spin-independent WIMP interactions which are >2× lower than previous CDMS results for high WIMP mass, and which exclude new parameter space for WIMPs with mass between 8 and 20 GeV/c² .

Measurement Of Deeply Virtual Compton Scattering At Hera, S. Chekanov, M. Derrick, D. Krakauer, J. H. Loizides, S. Magill, B. Musgrave, 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, A. Margotti, R. Nania, F. Palmonari, A. Pesci, G. Sartorelli, A. Zichichi, G. Aghuzumtsyan

Faculty Publications

The cross-section for deeply virtual Compton scattering in the reaction ep → eγp has been measured with the ZEUS detector at HERA using integrated luminosities of 95.0 pb-1 of e+p and 16.7 pb-1 of e-p collisions. Differential cross-sections are presented as a function of the exchanged-photon virtuality, Q2, and the centre-of-mass energy, W, of the γ*p system in the region 5 < Q2 < 100 GeV2 and 40 < W < 140 GeV. The measured cross-sections rise steeply with increasing W. The measurements are compared to QCD-based calculations. © 2003 Elsevier B.V. All rights reserved.

Measurement Of Conductivity And Charge Storage In Insulators Related To Spacecraft Charging, A. R. Frederickson, Jr Dennison

Conference Proceedings

Several methods have been combined to measure conductivity and charge storage in insulating spacecraft materials. In order to avoid insulator problems, the motions of conducting electrons and holes must prevent the development of large electric fields exceeding 1E5 V/cm, where problems occur in spacecraft insulators. Approximate knowledge of the electric fields is important. One must consider generation of mobile electrons and holes, their trapping, thermal de-trapping, mobility and recombination.

Classical methods to measure thin film insulator conductivity apply a constant voltage to two electrodes on the sample and measure the resulting current for tens of minutes. Under constant voltage, a …

Elucidating The Mechanisms Of Double Ionization Using Intense Half-Cycle, Single-Cycle, And Double Half-Cycle Pulses, G. Lagmago Kamta, Anthony F. Starace

Department of Physics and Astronomy: Faculty Publications

We investigate the interaction of a two-active electron system (Li^-) with intense single-cycle and double half-cycle pulses. The ‘‘intensity’’ and ‘‘frequency’’ considered correspond to the ‘‘multiphoton above-barrier regime.’’ For the single-cycle pulse (SCP), the electric field changes sign once, allowing electron wave packets created during the first half cycle to recollide with the parent ion when driven back by the field. For the double half-cycle pulse (DHP), however, the electric field does not change sign, and electron wave packets created during the first half cycle are not driven back to the parent ion. We find that both single …

Measurement Of The Mass Difference M(DS+)–M (D+) At Cdf Ii, Darin Acosta, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We present a measurement of the mass difference m(D_s⁺)– m (D⁺), where both the D_s⁺ and D⁺ are reconstructed in the Φπ⁺ decay channel. This measurement uses 11.6 pb^-1 of data collected by CDF II using the new displaced-track trigger. The mass difference is found to be m(D_s⁺)–m (D⁺)=99.41±0.38(stat)±0.21(syst) MeV/c².

Search For Lepton Flavor Violating Decays Of A Heavy Neutral Particle In Pp̅ Collisions At √S =1.8 Tev, Darin Acosta, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We report on a search for a high mass, narrow width particle that decays directly to eµ, eτ, or µτ. We use approximately 110 pb^-1 of data collected with the Collider Detector at Fermilab from 1992 to 1995. No evidence of lepton flavor violating decays is found. Limits are set on the production and decay of sneutrinos with R-parity violating interactions.