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2003

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Full-Text Articles in Physics

High Resolution Solar Observations In The Context Of Space Weather Prediction, Guo Yang Dec 2003

High Resolution Solar Observations In The Context Of Space Weather Prediction, Guo Yang

Dissertations

Space weather has a great impact on the Earth and human life. It is important to study and monitor active regions on the solar surface and ultimately to predict space weather based on the Sun's activity. In this study, a system that uses the full power of speckle masking imaging by parallel processing to obtain high-spatial resolution images of the solar surface in near real-time has been developed and built. The application of this system greatly improves the ability to monitor the evolution of solar active regions and to predict the adverse effects of space weather. The data obtained ...


Statistical Study Of Solar Radio Bursts, Gelu-Marius Nita Dec 2003

Statistical Study Of Solar Radio Bursts, Gelu-Marius Nita

Dissertations

The peak flux distribution of 40 years of solar radio burst data recorded by NOAA, as a function of frequency and time over a wide range of frequencies, was investigated to quantify the potential impact of radio bursts on wireless systems. Tables of fit parameters, which can be used to find burst occurrence rates in a number of frequency ranges, are presented. The typical power-law index of number density distribution, -1.8, is similar to that found in many hard X-ray studies. Significant changes were found in power-law index with frequency. The results may be useful for designers of current ...


Pion-Kaon Correlations In Central Au+Au Collisions At √SNn=130 Gev, Star Collaboration, T.D. Gutierrez Dec 2003

Pion-Kaon Correlations In Central Au+Au Collisions At √SNn=130 Gev, Star Collaboration, T.D. Gutierrez

Physics

Pion-kaon correlation functions are constructed from central Au+Au STAR data taken at √sNN=130  GeV by the STAR detector at the Relativistic Heavy Ion Collider (RHIC). The results suggest that pions and kaons are not emitted at the same average space-time point. Space-momentum correlations, i.e., transverse flow, lead to a space-time emission asymmetry of pions and kaons that is consistent with the data. This result provides new independent evidence that the system created at RHIC undergoes a collective transverse expansion.


Anomaly In Conformal Quantum Mechanics: From Molecular Physics To Black Holes, Horacio E. Camblong Dec 2003

Anomaly In Conformal Quantum Mechanics: From Molecular Physics To Black Holes, Horacio E. Camblong

Physics and Astronomy

A number of physical systems exhibit a particular form of asymptotic conformal invariance: within a particular domain of distances, they are characterized by a long-range conformal interaction (inverse square potential), the apparent absence of dimensional scales, and an SO(2,1) symmetry algebra. Examples from molecular physics to black holes are provided and discussed within a unified treatment. When such systems are physically realized in the appropriate strong-coupling regime, the occurrence of quantum symmetry breaking is possible. This anomaly is revealed by the failure of the symmetry generators to close the algebra in a manner shown to be independent of ...


Diffusion And Drift In Terahertz Emission At Gaas Surfaces, James Heyman, N Coates, A Reinhardt, G Strasser Dec 2003

Diffusion And Drift In Terahertz Emission At Gaas Surfaces, James Heyman, N Coates, A Reinhardt, G Strasser

James Heyman

No abstract provided.


Three-Pion Hanbury Brown–Twiss Correlations In Relativistic Heavy-Ion Collisions From The Star Experiment, Star Collaboration, T.D. Gutierrez Dec 2003

Three-Pion Hanbury Brown–Twiss Correlations In Relativistic Heavy-Ion Collisions From The Star Experiment, Star Collaboration, T.D. Gutierrez

Physics

Data from the first physics run at the Relativistic Heavy-Ion Collider at Brookhaven National Laboratory, Au+Au collisions at √sNN=130   GeV, have been analyzed by the STAR Collaboration using three-pion correlations with charged pions to study whether pions are emitted independently at freeze-out. We have made a high-statistics measurement of the three-pion correlation function and calculated the normalized three-particle correlator to obtain a quantitative measurement of the degree of chaoticity of the pion source. It is found that the degree of chaoticity seems to increase with increasing particle multiplicity.


Projectile-Shape Dependence Of Impact Craters In Loose Granular Media, K. A. Newhall Dec 2003

Projectile-Shape Dependence Of Impact Craters In Loose Granular Media, K. A. Newhall

Department of Physics Papers

We report on the penetration of cylindrical projectiles dropped from rest into a dry, noncohesive granular medium. The cylinder length, diameter, density, and tip shape are all explicitly varied. For deep penetrations, as compared to the cylinder diameter, the data collapse onto a single scaling law that varies as the 1/3 power of the total drop distance, the 1/2 power of cylinder length, and the 1/6 power of cylinder diameter. For shallow penetrations, the projectile shape plays a crucial role with sharper objects penetrating deeper.


Resonant Emergence Of Global And Local Spatiotemporal Order In A Nonlinear Field Model, Marcelo Gleiser, Rafael C. Howell Dec 2003

Resonant Emergence Of Global And Local Spatiotemporal Order In A Nonlinear Field Model, Marcelo Gleiser, Rafael C. Howell

Open Dartmouth: Faculty Open Access Scholarship

We investigate the nonequilibrium evolution of a scalar field in (2+1) dimensions. The field is set in a double-well potential in contact (open) or not (closed) with a heat bath. For closed systems, we observe the synchronized emergence of coherent spatiotemporal configurations, identified with oscillons. This initial global ordering degenerates into localized order until all oscillons disappear. We show that the synchronization is driven by resonant parametric oscillations of the field’s zero mode and that local ordering is only possible outside equipartition. None of these orderings occur for open systems.


Fundamental And Magnetic-Hardening Studies Of Rare-Earth And Nanocomposite Magnets, David J. Sellmyer, George C. Hadjipanayis Dec 2003

Fundamental And Magnetic-Hardening Studies Of Rare-Earth And Nanocomposite Magnets, David J. Sellmyer, George C. Hadjipanayis

David Sellmyer Publications

In this project we study new nanocrystalline and nanocomposite structures that have high potential for permanent-magnet development. These materials, which can be synthesized to have either very high or intermediate coercivities, have many applications in electric power, transportation, and information-storage industries. There is great interest in further development of understanding and application of these materials. Following are brief discussions of recent research highlights for the present grant.


Prediction Of Dopant Ionization Energies In Silicon: The Importance Of Strain, A. Rockett, Duane D. Johnson, S. V. Khare, B. R. Tuttle Dec 2003

Prediction Of Dopant Ionization Energies In Silicon: The Importance Of Strain, A. Rockett, Duane D. Johnson, S. V. Khare, B. R. Tuttle

Duane D. Johnson

Based on a hydrogenic state and strain changes upon defect charging, we propose a simple, parameter-free model that agrees well with the observed group III and V monovalent-impurity ionization energies in Si, revealing the importance of such strain effects. Changes in lattice strain upon defect charging are obtained via superposition and elasticity theory using atomic relaxations from density functional theory.


Magnetic And Transport Properties Of The V2– Vi3 Diluted Magnetic Semiconductor Sb2_Xmnxte3, Jeffrey Dyck, P. Svanda, P. Lostak, J. Horak, W. Chen, C. Uher Dec 2003

Magnetic And Transport Properties Of The V2– Vi3 Diluted Magnetic Semiconductor Sb2_Xmnxte3, Jeffrey Dyck, P. Svanda, P. Lostak, J. Horak, W. Chen, C. Uher

Jeffrey Dyck

We have measured electrical and magnetic properties of single crystals of Sb2_xMnxTe3 with x =0 – 0.045 at temperatures of 2 K to 300 K. Hall effect measurements indicate that each manganese atom donates approximately one hole to the valence band. The magnetic susceptibility is paramagnetic down to 2 K, and both Curie–Weiss and Brillouin analyses show that manganese substitutes for Sb and takes the Mn2+ state with S=5/2. Contrary to the case of III–V host matrices, manganese does not stimulate ferromagnetic order in the family of bulk layered V2– VI3 diluted magnetic semiconductors, at least ...


Strong Field Detachment Of A Negative Ion With Non-Zero Angular Momentum: Application To F-, M. V. Frolov, N. L. Manakov, E. A. Pronin, Anthony F. Starace Dec 2003

Strong Field Detachment Of A Negative Ion With Non-Zero Angular Momentum: Application To F-, M. V. Frolov, N. L. Manakov, E. A. Pronin, Anthony F. Starace

Anthony F. Starace Publications

We apply our recently developed, model-independent quantum approach for intense laser detachment of a weakly bound electron to interpret a recent experiment on above-threshold detachment (ATD) of the F- ion. We find that the measured electron energies correspond to the “Keldysh part” of the ATD spectrum, just below the onset of our predicted rescattering plateau. Overall, our predicted ATD spectrum (using a scaled peak intensity and focal averaging) is in excellent agreement with the experimental data, except for certain structures observed for electron energies above 12.6 eV that we attribute to known two-electron resonances of F-. A number of ...


Measurement Of Prompt Charm Meson Production Cross Sections In Pp̅ Collisions At √S=1.96 Tev, Darin Acosta, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Dec 2003

Measurement Of Prompt Charm Meson Production Cross Sections In Pp̅ Collisions At √S=1.96 Tev, Darin Acosta, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We report on measurements of differential cross sections d /dpT for prompt charm meson production in pp̅ collisions at √s=1.96 TeV using 5.8±0.3 pb-1 of data from the CDF II detector at the Fermilab Tevatron. The data are collected with a new trigger that is sensitive to the long lifetime of hadrons containing heavy flavor. The charm meson cross sections are measured in the central rapidity region |y|≤1 in four fully reconstructed decay modes: D0K- π+, D*+→D0 π+, D+K- π+ π+, Ds+→ Φπ+, and their charge conjugates ...


Decoherence-Driven Cooling Of A Degenerate Spinor Bose Gas, H. J. Lewandowski, J. M. Mcguirk, D. M. Harber, Eric A. Cornell Dec 2003

Decoherence-Driven Cooling Of A Degenerate Spinor Bose Gas, H. J. Lewandowski, J. M. Mcguirk, D. M. Harber, Eric A. Cornell

Physics Faculty Contributions

We investigate the relationship between the coherence of a partially Bose-condensed spinor gas and its temperature. We observe cooling of the normal component driven by decoherence as well as the effect of temperature on decoherence rates.


Linear Perturbations In Brane Gas Cosmology, Scott Watson, Robert H. Brandenberger Dec 2003

Linear Perturbations In Brane Gas Cosmology, Scott Watson, Robert H. Brandenberger

Physics

We consider the effect of string inhomogeneities on the time dependent background of Brane Gas Cosmology. We derive the equations governing the linear perturbations of the dilaton-gravity background in the presence of string matter sources. We focus on long wavelength fluctuations and find that there are no instabilities. Thus, the predictions of Brane Gas Cosmology are robust against the introduction of linear perturbations. In particular, we find that the stabilization of the extra dimensions (moduli) remains valid in the presence of dilaton and string perturbations.


United States Patent: Application Of High Spin Polarization Materials In Two Terminal Non-Volatile Bistable Memory Devices, Bernard Doudin, Andrei Sokolov, Cheol-Soo Yang, Lu Yuan, Sy-Hwang Liou Dec 2003

United States Patent: Application Of High Spin Polarization Materials In Two Terminal Non-Volatile Bistable Memory Devices, Bernard Doudin, Andrei Sokolov, Cheol-Soo Yang, Lu Yuan, Sy-Hwang Liou

Si-Hwang Liou Publications

Disclosed are two terminal bistable memory cells having least two high-spin polarization magnetic material junctions which are separated from one another by electron trap site defect containing insulator. The two terminal bistable memory cells demonstrate stable, low current readable, hysteretic resistance states which are set by the flow of a relatively high, (eg. a milliamp or less), plus or minus polarity D.C. current therethrough, which resistance is monitored by lower magnitude A.C. or D.C. current flow therethrough. Preferred cells have at least one Cr02/Cr203/ CrO2 sequence but typically have multiple Cr0 ...


Physics Department News, December 2003, College Of Arts And Sciences Dec 2003

Physics Department News, December 2003, College Of Arts And Sciences

Physics Newsletter

Contents from Volume 2, Issue 2:

  • A Note from the Editor
  • From the Chair
  • What’s New at the University
  • Faculty Highlights
  • Staff Highlights
  • Accelerator Upgrade 5
  • PhysTEC
  • Distinguished Alumni Award
  • Alumni News
  • Recent Guest
  • Goldwater Scholar
  • New Grants
  • Student Awards
  • Recent Graduates
  • Department Roster
  • Photo Gallery
  • Feedback/Update Reply Form


Physica: The Newsletter Of Utep's Department Of Physics, Utep Department Of Physics Dec 2003

Physica: The Newsletter Of Utep's Department Of Physics, Utep Department Of Physics

The Department of Physics

Electronic newsletter of UTEP's Department of Physics, December 2003.


A High Shear-Rate Optical Rheometer For Complex Fluids, Khaled S. Mriziq Dec 2003

A High Shear-Rate Optical Rheometer For Complex Fluids, Khaled S. Mriziq

Doctoral Dissertations

A parallel-plate optical rheometer in a magnetic-disc drive configuration has been designed and constructed of optically transparent materials and operating with a very small gap to obtain rheological and structural measurements at very high shear rates.

The friction force at the disk-slider interface has been measured as a function of sliding speed while the film thickness was monitored in situ using a capacitance technique. The shear rate is calculated from the film thickness and the sliding speed. A thin film can be applied on the disk, which allows very high-shear-rate measurements at low sliding speeds with negligible viscous heating.

Both ...


Production In Au-Au Collisions, Robert Jason Newby Dec 2003

Production In Au-Au Collisions, Robert Jason Newby

Doctoral Dissertations

This thesis presents the first J/ Ψ production analysis of Au+Au reactions at forward rapidity at p √sNN = 200 GeV. In the second year of RHIC running, design energy was achieved in the collisions of both Au+Au ions and proton+proton reactions. The production of the J/Ψ is measured by the PHENIX experiment in Au+Au collisions as well as in proton-proton collisions. The scientific goal is to investigate the nature of hot, dense nuclear matter capitalizing on the unique properties of the J/ Ψ as a probe of this matter. Recent experimental results by the NA50 ...


Comparisons Of Electron Fluxes Measured In The Crustal Fields At Mars By The Mgs Magnetometer/Electron Reflectometer Instrument With A B Field-Dependent Transport Code, Michael W. Liemohn, David L. Mitchell, Andrew F. Nagy, Jane L. Fox, Tamara W. Reimer, Yingjuan J. Ma Dec 2003

Comparisons Of Electron Fluxes Measured In The Crustal Fields At Mars By The Mgs Magnetometer/Electron Reflectometer Instrument With A B Field-Dependent Transport Code, Michael W. Liemohn, David L. Mitchell, Andrew F. Nagy, Jane L. Fox, Tamara W. Reimer, Yingjuan J. Ma

Physics Faculty Publications

We compare Mars Global Surveyor (MGS) magnetometer/electron reflectometer data with results from a B field–dependent kinetic transport code for ‘‘superthermal’’ electrons. The photoelectrons created on crustal field loops, when they are on the dayside, allow for the exploration of the magnetic topology and the upper atmospheric density structure. A case study of a typical orbit of the MGS satellite through the strong crustal field region in the southern hemisphere of Mars is examined. The results indicate that the low solar wind dynamic pressure during the selected orbit allowed for the expansion of the crustal field line to relatively ...


Fabrication And Characterization Of N-Zno/P-Algan Heterojunction Light-Emitting Diodes On 6h-Sic Substrates, Y. I. Alivov, E. V. Kalinina, A. E. Cherenkov, David C. Look, B. M. Ataev, A. K. Omaev, M. V. Chukichev, D. M. Bagnall Dec 2003

Fabrication And Characterization Of N-Zno/P-Algan Heterojunction Light-Emitting Diodes On 6h-Sic Substrates, Y. I. Alivov, E. V. Kalinina, A. E. Cherenkov, David C. Look, B. M. Ataev, A. K. Omaev, M. V. Chukichev, D. M. Bagnall

Physics Faculty Publications

We report on the fabrication of n-ZnO/p-AlGaN heterojunction light-emitting diodes on 6H-SiC substrates. Hydride vapor phase epitaxy was used to grow p-type AlGaN, while chemical vapor deposition was used to produce the n-type ZnO layers. Diode-like, rectifying I-V characteristics, with threshold voltage ~3.2 V and low reverse leakage current ~10-7 A, are observed at room temperature. Intense ultraviolet emission with a peak wavelength near 389 nm is observed when the diode is forward biased; this emission is found to be stable at temperatures up to 500 K and shown to originate from recombination within the ZnO.


“Don’T Tell Me, I’Ll Find Out”: Robert Karplus—A Science Education Pioneer, Robert Fuller Dec 2003

“Don’T Tell Me, I’Ll Find Out”: Robert Karplus—A Science Education Pioneer, Robert Fuller

Robert G. Fuller Publications and Presentations

Robert Karplus (1927–90), who began his career as a brilliant theoretical physicist, switched to science education in the early 1960s. He made many substantial contributions to this field in addition to developing a complete K–6 hands-on science curriculum. Karplus provided his curriculum with a sound epistemological foundation, based on the work of Piaget. He developed an effective classroom teaching strategy, the learning cycle. He and his team used a scientific approach to curriculum development. They focused on teacher development. Karplus was committed to science for ALL students. Through science activities he sought to share the joy of discovery ...


Computational Magnetohydrodynamic Investigation Of Flux Compression And Implosion Dynamics In A Z-Pinch Plasma With An Azimuthally Opposed Magnetic Field Configuration, Kyle John Peterson Dec 2003

Computational Magnetohydrodynamic Investigation Of Flux Compression And Implosion Dynamics In A Z-Pinch Plasma With An Azimuthally Opposed Magnetic Field Configuration, Kyle John Peterson

Doctoral Dissertations

Magnetic flux compression is a well established technique for the generation of ultrahigh magnetic fields, large currents, and large energy densities. It has been suggested as a means for power density amplification on Z-pinch generators such as Decade Quad, at Arnold Engineering Development Center, and it may be especially suitable as a means for producing higher powers of K-shell radiation from high atomic number loads such as titanium. Although many one-dimensional models of flux compression on Z-pinch generators exist, an improvement in understanding is needed about the physics and implosion dynamics on a two-dimensional level. To this end, a two-dimensional ...


Isotropic Loop Quantum Cosmology With Matter. Ii. The Lorentzian Constraint, F. Hinterleitner, Seth Major Dec 2003

Isotropic Loop Quantum Cosmology With Matter. Ii. The Lorentzian Constraint, F. Hinterleitner, Seth Major

Articles

The Lorentzian Hamiltonian constraint is solved for isotropic loop quantum cosmology coupled to a massless scalar field. As in the Euclidean case, the discreteness of quantum geometry removes the classical singularity from the quantum Friedmann models. In spite of the absence of the classical singularity, a modified DeWitt initial condition is incompatible with a late-time smooth behavior. Further, the smooth behavior is recovered only for positive or negatives times but not both. An important feature, which is shared with the Euclidean case, is a minimal initial energy of the order of the Planck energy required for the system to evolve ...


Biological Permanent Magnets, Richard B. Frankel Dec 2003

Biological Permanent Magnets, Richard B. Frankel

Physics

Magnetotactic bacteria orient and migrate along magnetic field lines. Each cell is essentially a self-propelled magnetic dipole. The magnetic properties of these bacteria have been determined by a variety of techniques, including pulsed hysteresis measurements on single cells.


Irradiation Induced Order-Dis Order Transformations In Ni-Mo Alloys, Ovidiu F. Toader Dec 2003

Irradiation Induced Order-Dis Order Transformations In Ni-Mo Alloys, Ovidiu F. Toader

Dissertations

No abstract provided.


Midrapidity Neutral-Pion Production In Proton-Proton Collisions At Root S 200 Gev, S. S. Adler, Sergey Belikov, S. Bhagavatula, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, Jan Rak, Marzia Rosati, F. K. Wohn, Et Al., Phenix Collaboration Dec 2003

Midrapidity Neutral-Pion Production In Proton-Proton Collisions At Root S 200 Gev, S. S. Adler, Sergey Belikov, S. Bhagavatula, Paul Constantin, Nathan C. Grau, John C. Hill, John G. Lajoie, Alexandre Lebedev, Craig Ogilvie, Jan Rak, Marzia Rosati, F. K. Wohn, Et Al., Phenix Collaboration

Physics and Astronomy Publications

The invariant differential cross section for inclusive neutral-pion production in p+p collisions at root s=200 GeV has been measured at midrapidity (\eta\<0.35) over the range 1 < p(T) less than or similar to 14 GeV/c by the PHENIX experiment at the Relativistic Heavy Ion Collider. Predictions of next-to-leading order perturbative QCD calculations are consistent with these measurements. The precision of our result is sufficient to differentiate between prevailing gluon-to-pion fragmentation functions.


Afci Quarterly Input – Unlv October Through December, 2003, Harry Reid Center For Environmental Studies. Nuclear Science And Technology Division Dec 2003

Afci Quarterly Input – Unlv October Through December, 2003, Harry Reid Center For Environmental Studies. Nuclear Science And Technology Division

Transmutation Research Program Reports (TRP)

Quarterly report highlighting research projects and objectives 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.


Development Of Dose Conversion Coefficients For Radionuclides Produced In Spallation Neutron Sources: Quarterly Progress Report 8/20/03 – 12/01/03, Phillip W. Patton, Mark Rudin Dec 2003

Development Of Dose Conversion Coefficients For Radionuclides Produced In Spallation Neutron Sources: Quarterly Progress Report 8/20/03 – 12/01/03, Phillip W. Patton, Mark Rudin

Transmutation Sciences Physics (TRP)

A research consortium comprised of representatives from several universities and national laboratories has been established as part of this project to generate internal and external dose conversion coefficients for radionuclides produced in spallation neutron sources. Information obtained from this multi-year study will be used to support the siting and licensing of future accelerator-driven nuclear initiatives within the U.S. Department of Energy complex, including the Spallation Neutron Source (SNS) and Accelerator Production of Tritium (APT) Projects. Determination of these coefficients will also fill data gaps for several hundred radionuclides that exist in Federal Guide Report No. 11 and in Publications ...