Open Access. Powered by Scholars. Published by Universities.®
- Institution
-
- University of Nebraska - Lincoln (3576)
- Missouri University of Science and Technology (2387)
- Old Dominion University (1925)
- Utah State University (1829)
- TÜBİTAK (1382)
-
- University of Kentucky (965)
- Air Force Institute of Technology (961)
- California Polytechnic State University, San Luis Obispo (922)
- Syracuse University (908)
- City University of New York (CUNY) (664)
- University of Texas Rio Grande Valley (663)
- University of Central Florida (623)
- Portland State University (596)
- University of Nevada, Las Vegas (565)
- Technological University Dublin (541)
- Brigham Young University (502)
- Michigan Technological University (495)
- Wright State University (488)
- University of South Carolina (486)
- University of New Mexico (467)
- Chapman University (433)
- University of Arkansas, Fayetteville (359)
- Virginia Commonwealth University (339)
- Florida Institute of Technology (338)
- Cleveland State University (283)
- University of Dayton (266)
- Karbala International Journal of Modern Science (264)
- Western Michigan University (258)
- Andrews University (225)
- Dartmouth College (225)
- Keyword
-
- Physics (842)
- Department of Physics (327)
- Optics (182)
- Spectroscopy (166)
- Scattering (146)
-
- Graphene (139)
- Thin films (139)
- Galaxies (138)
- Gravitational waves (129)
- Physical Sciences (126)
- Simulation (123)
- Polarization (122)
- Electron (121)
- Plasma (121)
- Superconductivity (116)
- Nanoparticles (115)
- Radiation (113)
- Pure sciences (105)
- Quantum chromodynamics (104)
- Ionization (101)
- Machine learning (101)
- Cavity (96)
- Laser (94)
- Photoluminescence (94)
- Quantum physics (93)
- Condensed matter (90)
- Hadron-Hadron Scattering (88)
- CMS (87)
- Cosmology (86)
- Lasers (83)
- Publication Year
- Publication
-
- Physics Faculty Publications (2115)
- Physics Faculty Research & Creative Works (1939)
- Turkish Journal of Physics (1382)
- Faculty Publications (1214)
- Theses and Dissertations (1154)
-
- Physics (970)
- Physics and Astronomy Faculty Publications (841)
- All Physics Faculty Publications (658)
- Electronic Theses and Dissertations (617)
- Physics & Astronomy Faculty Publications (587)
- Physics Faculty Publications and Presentations (563)
- Physics - All Scholarship (554)
- Department of Physics and Astronomy: Faculty Publications (374)
- Kenneth Bloom Publications (369)
- Articles (366)
- Mathematics, Physics, and Computer Science Faculty Articles and Research (351)
- Publications and Research (333)
- Physics & Astronomy ETDs (299)
- Aerospace, Physics, and Space Science Faculty Publications (298)
- Peter Dowben Publications (284)
- David Sellmyer Publications (278)
- Masters Theses (274)
- Dissertations (272)
- Karbala International Journal of Modern Science (264)
- International Building Physics Conference 2018 (255)
- Physics Publications (230)
- Anthony F. Starace Publications (229)
- Doctoral Dissertations (214)
- Dissertations, Theses, and Capstone Projects (213)
- Electrical & Computer Engineering Faculty Publications (199)
- Publication Type
- File Type
Articles 28321 - 28350 of 34250
Full-Text Articles in Entire DC Network
Robust Test For Detecting Nonstationarity In Data From Gravitational Wave Detectors, Soumya Mohanty
Robust Test For Detecting Nonstationarity In Data From Gravitational Wave Detectors, Soumya Mohanty
Physics & Astronomy Faculty Publications
It is difficult to choose detection thresholds for tests of nonstationarity that assume a priori a noise model if the data are statistically uncharacterized to begin with. This is a potentially serious problem when an automated analysis is required, as would be the case for the huge data sets that large interferometric gravitational wave detectors will produce. A solution is proposed in the form of a robust time-frequency test for detecting nonstationarity whose threshold for a specified false alarm rate is almost independent of the statistical nature of the ambient stationary noise. The efficiency of this test in detecting bursts …
A Solar Comparison, Larry Weinstein
A Solar Comparison, Larry Weinstein
Physics Faculty Publications
[First paragraph] Gilbert Ward [Phys.Teach 38, 333 (Sept. 2000)] states, "You emit more than 7000 times as much heat per unit mass as the Sun does." This difference was pointed out to me much more graphically by Brian Quinn many years ago as, "If the sun were made out of gerbils, the Earth would be incinerated."
Textured Mos 2 Thin Films Obtained On Tungsten: Electrical Properties Of The W/Mos 2 Contact, E. Gourmelon, J. C. Bernède, J. Pouzet, S. Marsillac
Textured Mos 2 Thin Films Obtained On Tungsten: Electrical Properties Of The W/Mos 2 Contact, E. Gourmelon, J. C. Bernède, J. Pouzet, S. Marsillac
Electrical & Computer Engineering Faculty Publications
Textured films of molybdenum disulfide have been obtained by solid state reaction between the constituents in thin films form when a (200) oriented tungsten sheet is used as substrate. The crystallites have their c axis perpendicular to the plane of the substrate. The annealing conditions are T=1073K and t=30 min. The films are stoichoimetric and p type. Such highly textured films are achieved without foreign atom addition (Ni, Co...). It appears, as shown by x-ray photoelectron spectroscopy, that a thin WS2 layer is present at the interface W/MoS2. The crystallization process is discussed by a …
Critical Adsorption On Defects In Ising Magnets And Binary Alloys, Andreas Hanke
Critical Adsorption On Defects In Ising Magnets And Binary Alloys, Andreas Hanke
Physics & Astronomy Faculty Publications
Long-range correlations in a magnet close to its critical point or in a binary alloy close to a continuous order-disorder transition can substantially enhance the effect of local perturbations. It is demonstrated using a position-space renormalization procedure that quasi-one-dimensional defects which break the symmetry of the order parameter have pronounced effects: They cause long-range critical adsorption profiles and give rise to new universal critical exponents, which are identified and calculated using field-theoretical methods.
Heavy Metal Content In Water Hyacinth (Eichhornia Crassipes (Mart) Solms.) From Lake Victoria Shore, Tanzania, Nk Mohammed, In Makundi
Heavy Metal Content In Water Hyacinth (Eichhornia Crassipes (Mart) Solms.) From Lake Victoria Shore, Tanzania, Nk Mohammed, In Makundi
Tanzania Journal of Science
Water hyacinth (Eichhornia crassipes (Mart) Solms,) samples from Lake Victoria shore were analysed for heavy metal pollution using Energy Dispersive X-ray Fluorescence Spectroscopy (EDXRF). The roots of the water hyacinth samples were collected from areas influenced by industrial and domestic sewage and little influenced area. Water hyacinth from industrial area and those from sewage discharge points had higher concentrations of heavy metals than that from the little disturbed area.
Viscoelastic Depinning Of Driven Systems: Mean-Field Plastic Scallops, M. Cristina Marchetti, Alan Middleton, Thomas Prellberg
Viscoelastic Depinning Of Driven Systems: Mean-Field Plastic Scallops, M. Cristina Marchetti, Alan Middleton, Thomas Prellberg
Physics - All Scholarship
We have investigated the mean field dynamics of an overdamped viscoelastic medium driven through quenched disorder. The model introduced incorporates coexistence of pinned and sliding degrees of freedom and can exhibit continuous elastic depinning or first order hysteretic depinning. Numerical simulations indicate mean field instabilities that correspond to macroscopic stick-slip events and lead to premature switching. The model is relevant for the dynamics of driven vortex arrays in superconductors and other extended disordered systems.
Nanocomposite Copt:C Films For Extremely High-Density Recording, M. Yu, Yi Liu, A. Moser, D. Weller, David J. Sellmyer
Nanocomposite Copt:C Films For Extremely High-Density Recording, M. Yu, Yi Liu, A. Moser, D. Weller, David J. Sellmyer
David Sellmyer Publications
Nanocomposite CoPt:C films were investigated as potential media for extremely high-density recording. An annealing temperature of over 600 °C is necessary to form nanocomposite CoPt:C films consisting of C matrix and fct CoPt nanocrystallites with grain sizes of 8–20 nm and coercivities of 3–12 kOe. Coercivity and grain size increase with increasing annealing temperature and decreasing C concentration and they are insensitive to film thickness. The average activation volumes are about 0.9×10-18 cm3. The properties of these nanocomposite CoPt:C films can be tailored to satisfy the thermal stability, coercivity, and media noise requirements for extremely high-density recording.
Electrical Resistivity Of A Thin Metallic Film, Horacio E. Camblong
Electrical Resistivity Of A Thin Metallic Film, Horacio E. Camblong
Physics and Astronomy
The electrical resistivity of a pure sample of a thin metallic film is found to depend on the boundary conditions. This conclusion is supported by a free-electron model calculation and confirmed by an ab initio relativistic Korringa-Kohn-Rostoker computation. The low-temperature resistivity is found to be zero for a free-standing film (reflecting boundary conditions) but nonzero when the film is sandwiched between two semi-infinite samples of the same material (outgoing boundary conditions). In the latter case, this resistivity scales inversely with the number of monolayers and is due to the background diffusive scattering by a finite lattice.
Linear Optics Simulations Of The Quantum Baker’S Map, John C. Howell, John A. Yeazell
Linear Optics Simulations Of The Quantum Baker’S Map, John C. Howell, John A. Yeazell
Mathematics, Physics, and Computer Science Faculty Articles and Research
The unitary evolution of linear optics can be used to model quantum computational networks. In this paper, a quantum simulation of a classically chaotic map (the baker’s map) is developed using linear optics. Two different models are presented. The first model employs only 50-50 beam splitters and phase shifters to simulate universal 2-qubit gates of a quantum computer. The second model uses the discrete Fourier transform generated by symmetric N×N fiber couplers. If single photons are used as inputs for these linear optics models, the result is a physical realization of the quantum baker’s map.
Interaction Second Virial Coefficients From A Recent H2-Co Potential Energy Surface, J. Gottfried, George C. Mcbane
Interaction Second Virial Coefficients From A Recent H2-Co Potential Energy Surface, J. Gottfried, George C. Mcbane
Peer Reviewed Articles
No abstract provided.
Creation Of An Ultracold Neutral Plasma, Scott D. Bergeson, T. C. Killian, S. Kulin, L. A. Orozco, C. Orzel, S. L. Rolston
Creation Of An Ultracold Neutral Plasma, Scott D. Bergeson, T. C. Killian, S. Kulin, L. A. Orozco, C. Orzel, S. L. Rolston
Faculty Publications
We report the creation of an ultracold neutral plasma by photoionization of laser-cooled xenon atoms. The charge carrier density is as high as 2×10^9 cm^-3, and the temperatures of electrons and ions are as low as 100 mK and 10 uK, respectively. Plasma behavior is evident in the trapping of electrons by the positive ion cloud when the Debye screening length becomes smaller than the size of the sample. We produce plasmas with parameters such that both electrons and ions are strongly coupled.
Video And Photometric Observations Of A Sprite In Coincidence With A Meteor-Triggered Jet Event, D. M. Suszcynsky, R. Strabley, R. Roussel-Dupre, E. M.D. Symbalisty, R. A. Armstrong, W. A. Lyons, Michael J. Taylor
Video And Photometric Observations Of A Sprite In Coincidence With A Meteor-Triggered Jet Event, D. M. Suszcynsky, R. Strabley, R. Roussel-Dupre, E. M.D. Symbalisty, R. A. Armstrong, W. A. Lyons, Michael J. Taylor
All Physics Faculty Publications
Video and photometric observations of a meteor-triggered “jet” event in association with the occurrence of a sprite were collected during the SPRITES '98 campaign. The event raises interest in the question of possible meteoric triggering of upper atmospheric transients as originally suggested by Muller [1995]. The event consisted of three stages: (1) the observation of a moderately bright meteor, (2) the development of a sprite in the immediate vicinity of the meteor as the meteor reached no lower than ∼70 km altitude, and (3) a slower-forming jet of luminosity that appeared during the late stages of the sprite and propagated …
Photodetachment Of He- In The Vicinity Of The He* (N=3, 4, And 5) Thresholds, Chien-Nan Liu, Anthony F. Starace
Photodetachment Of He- In The Vicinity Of The He* (N=3, 4, And 5) Thresholds, Chien-Nan Liu, Anthony F. Starace
Anthony F. Starace Publications
A comprehensive eigenchannel R-matrix study of photodetachment of He-(1 s2s2p 4P0 (1 ) is presented for the energy region of the Hesnl3l) thresholds, where 3<~n<~5. Over this energy region we present all partial cross sections which have been measured experimentally, including theoretical predictions (1 for the Hes3p 3P ( ) partial cross section, as well as energies and widths for all resonances, and identifications of all major ones. Near the Hen=3) thresholds, we predict two 4De resonances that to our knowledge have previously been neither predicted nor observed, and present results showing their effects on partial cross sections and photoelectron angular distributions; …~5.>~
Microscopic Origins Of Heliclinic Phases In Smectic Liquid Crystals, Jonathan J. Stott, Rolfe G. Petschek
Microscopic Origins Of Heliclinic Phases In Smectic Liquid Crystals, Jonathan J. Stott, Rolfe G. Petschek
Faculty Scholarship
In a previous article [Phys. Rev. E 60, 1799 (1999)], the authors considered a model Landau free energy that explained the ferriclinic phases of chiral smectic liquid crystals as a series of short period helical modulations. In this paper we begin with a physically more realistic, more microscopic interlayer free energy and show how our previous work can be derived using only simple short-ranged interactions. We then discuss what additional information this provides about the Landau coefficients used previously to construct the phase diagram for the heliclinic phases of chiral smectic liquid crystals. Finally, we investigate a means for explicitly …
Measurement Of TC Suppression In Tungsten Using Magnetic Impurities, Betty A. Young, T. Saab, Blas Cabrera, J. J. Cross, R. M. Clarke, R. A. Abusaidi
Measurement Of TC Suppression In Tungsten Using Magnetic Impurities, Betty A. Young, T. Saab, Blas Cabrera, J. J. Cross, R. M. Clarke, R. A. Abusaidi
Physics
We have measured the effects of dilute magnetic-atom doping on the superconducting transition temperature of tungsten thin films. Our “Tc tuning” technique is accurate, precise, and simple. Experiments were performed using dc-magnetron-sputtered tungsten films with undoped values of Tc in the range of 70–150 mK. The magnetic-atom doping was achieved using ion implantation. Specific Tc suppressions of between 5% and 65% were targeted and observed in this study. The transition width of each undoped sample was ≈1 mK and the transition widths remained sharp after implantation with 56Fe+ ions. Our data are in good agreement …
Oxygen Pressure-Tuned Epitaxy And Optoelectronic Properties Of Laser-Deposited Zno Films On Sapphire, S. Choopun, R. D. Vispute, W. Noch, A. Balsamo, R. P. Sharma, T. Venkatesan, A. Iliadis, David C. Look
Oxygen Pressure-Tuned Epitaxy And Optoelectronic Properties Of Laser-Deposited Zno Films On Sapphire, S. Choopun, R. D. Vispute, W. Noch, A. Balsamo, R. P. Sharma, T. Venkatesan, A. Iliadis, David C. Look
Physics Faculty Publications
Influence of oxygen pressure on the epitaxy, surface morphology, and optoelectronic properties has been studied in the case of ZnO thin films grown on sapphire ~0001! by pulsed-laser deposition. Results of Rutherford backscattering and ion channeling in conjunction with atomic force microscopy clearly indicate that the growth mode, degree of epitaxy, and the defect density strongly depend on the oxygen background pressure during growth. It is also found that the growth mode and the defects strongly influence the electron mobility, free-electron concentration, and the luminescence properties of the ZnO films. By tuning the oxygen pressure during the initial and the …
Molecular-Dynamics Study Of Phase Transitions In Alkali Azides, M. M. Ossowski, John R. Hardy, Robert W. Smith
Molecular-Dynamics Study Of Phase Transitions In Alkali Azides, M. M. Ossowski, John R. Hardy, Robert W. Smith
Physics Faculty Publications
An account is presented of our studies of the order-disorder phase transitions in KN3, RbN3, and CsN3. These are based on parameter-free interionic potentials based on the Gordon-Kim modified electron-gas formalism extended to molecular ions. We performed static structural relaxations and supercell molecular dynamics and predicted with reasonable accuracy the temperatures for the onset of the transitions. In particular, we address the question of how the N3- ions reorient to yield the transitions. We found the existence of NaCl-type high-temperature phases in disordered KN3 and RbN3 and argue that this …
Initial State Dependence Of Low-Energy Electron Emission In Fast Ion Atom Collisions, Robert Moshammer, Pablo Daniel Fainstein, Michael Schulz, Wayne M. Schmitt, Holger Kollmus, Rido Mann, Siegbert Hagmann, Joachim Hermann Ullrich
Initial State Dependence Of Low-Energy Electron Emission In Fast Ion Atom Collisions, Robert Moshammer, Pablo Daniel Fainstein, Michael Schulz, Wayne M. Schmitt, Holger Kollmus, Rido Mann, Siegbert Hagmann, Joachim Hermann Ullrich
Physics Faculty Research & Creative Works
Single and multiple ionization of neon and argon atoms by 3.6 MeV/u Au53+ impact has been explored in kinematically complete experiments. Doubly differential cross sections for low-energy electron emission have been obtained for a defined charge state of the recoiling target ion and the receding projectile. Observed target specific structures in the electron continuum are attributable to the nodal structure of the initial bound state momentum distribution. The experimental data are in excellent accord with continuum-distorted-wave eikonal-initial-state single ionization calculations if multiple ionization is considered appropriately.
Detailed Dynamics Of Electron Beams Self-Trapped And Accelerated In A Self-Modulated Laser Wakefield, Shouyuan Chen, M. Krishnan, Anatoly Maksimchuk, R. Wagner, Donald P. Umstadter
Detailed Dynamics Of Electron Beams Self-Trapped And Accelerated In A Self-Modulated Laser Wakefield, Shouyuan Chen, M. Krishnan, Anatoly Maksimchuk, R. Wagner, Donald P. Umstadter
Donald Umstadter Publications
The electron beam generated in a self-modulated laser-wakefield accelerator is characterized in detail. A transverse normalized emittance of 0.06 π mm mrad, the lowest ever for an electron injector, was measured for 2 MeV electrons. The electron beam was observed to have a multicomponent beam profile and energy distribution. The latter also undergoes discrete transitions as the laser power or plasma density is varied. In addition, dark spots that form regular modes were observed in the electron beam profile. These features are explained by analysis and test particle simulations of electron dynamics during acceleration in a three-dimensional plasma wakefield.
Characterisation Of The Effects Of Time And Pressure On A Group Of Electronic Voltage Standards, James Kevin Armstrong
Characterisation Of The Effects Of Time And Pressure On A Group Of Electronic Voltage Standards, James Kevin Armstrong
Masters
Although primary metrology laboratories use standards based on the Josephson effect to maintain a local reference standard for dc voltage, artefact standards are still the standard of choice in many secondary laboratories. The National Metrology Laboratory, Dublin maintains a local reference standard for dc voltage by means of an ensemble of Zener-diode based electronic voltage standard units. Electronic voltage standards have a number of shortcomings over Josephson standards for use as a local reference standard. In particular their output voltages are influenced by several external factors. In order to make optimum use of the NML reference standard it is important …
A Numerical Simulation Of A Carbon Black Suspension Cell Via A Time-Reversed, Double Layer Compute Algorithm, Gregg T. Anderson
A Numerical Simulation Of A Carbon Black Suspension Cell Via A Time-Reversed, Double Layer Compute Algorithm, Gregg T. Anderson
Theses and Dissertations
A numerical simulation of a carbon black suspension cell is explored which models a laser-induced plasma within a liquid ethanol medium of approximately 1 mm thickness. The simulation model assumes a laser pulse with a pulse width of approximately 9 nsecs propagating in the left-to-right direction striking the front surface of the medium and focusing to a spot within the liquid volume. When the energy density within a given irradiated volume is sufficiently high, it ignites the carbon particles and generates a large number of free electrons, i.e., a plasma. The plasma couples with the in-coming laser energy on a …
Application Of The Interaction Picture To Reactive Scattering In One Dimension, Michael J. Maclachlan
Application Of The Interaction Picture To Reactive Scattering In One Dimension, Michael J. Maclachlan
Theses and Dissertations
The interaction picture is used together with the channel-packet method in a new time-dependent approach to compute reactive scattering matrix elements. The channelpacket method enables the use of the interaction picture for computing reactive S-matrix elements by splitting the computational effort into two parts. First, asymptotic reactant and product wavepackets are individually propagated into the interaction region of the potential to form Moller states. The interaction picture, in contrast to the usual Schrödinger picture of quantum mechanics, is so constructed that a wavefunction that experiences no change in potential (that is, a free-particle wavefunction) remains always fixed, with no translation …
Molecular-Dynamics Study Of Phase Transitions In Alkali Azides, M. M. Ossowski, John R. Hardy, R. W. Smith
Molecular-Dynamics Study Of Phase Transitions In Alkali Azides, M. M. Ossowski, John R. Hardy, R. W. Smith
John R. Hardy Papers
An account is presented of our studies of the order-disorder phase transitions in KN3, RbN3, and CsN3. These are based on parameter-free interionic potentials based on the Gordon-Kim modified electron-gas formalism extended to molecular ions. We performed static structural relaxations and supercell molecular dynamics and predicted with reasonable accuracy the temperatures for the onset of the transitions. In particular, we address the question of how the N3- ions reorient to yield the transitions. We found the existence of NaCl-type high-temperature phases in disordered KN3 and RbN3 and argue that this …
Measurement Of The B0B̅0 Oscillation Frequency Using L-D*+ Pairs And Lepton Flavor Tags, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration
Measurement Of The B0B̅0 Oscillation Frequency Using L-D*+ Pairs And Lepton Flavor Tags, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration
Kenneth Bloom Publications
The oscillation frequency Δmd of B0B̅0 mixing is measured using the partially reconstructed semileptonic decay B̅0→l- ν̅ D*+X. The data sample was collected with the CDF detector at the Fermilab Tevatron collider during 1992–1995 by triggering on the existence of two lepton candidates in an event, and corresponds to about 110 pb-1 of p̅p collisions at √s =1.8 TeV. We estimate the proper decay time of the B̅0 meson from the measured decay length and reconstructed momentum of the l-D*+ system. The charge of …
Lattice-Stiffening Transition In Copolymer Films Of Vinylidene Fluoride (70%) With Trifluoroethylene (30%), C.N. Borca, Shireen Adenwalla, Jaewu Choi, P.T. Sprungerr, Stephen Ducharme, Lee Robertson, S.P. Palto, Jianglai Liu, Matt Poulsen, V.M. Fridkin, H. You, Peter A. Dowben
Lattice-Stiffening Transition In Copolymer Films Of Vinylidene Fluoride (70%) With Trifluoroethylene (30%), C.N. Borca, Shireen Adenwalla, Jaewu Choi, P.T. Sprungerr, Stephen Ducharme, Lee Robertson, S.P. Palto, Jianglai Liu, Matt Poulsen, V.M. Fridkin, H. You, Peter A. Dowben
Peter Dowben Publications
We report the discovery of a compressibility phase transition at 160 K in crystalline copolymer films of vinylidene fluoride ( 70%) with trifluoroethylene ( 30%). This phase transition is distinct from the known bulk ferroelectric-paraelectric phase transition at 353 K and surface ferroelectric phase transition at 295 K. The new phase transition is characterized by an increase in the effective Debye temperature from 48 to 245 K along the 〈010〉 direction as the temperature falls below 160 K. This phase transition is evident in neutron scattering, x-ray diffraction, angle-resolved photoemission, and in the dipole active phonon modes in electron energy-loss …
Interacting Topological Defects On Frozen Topographies, Mark Bowick, David R. Nelson, Alex Travesset
Interacting Topological Defects On Frozen Topographies, Mark Bowick, David R. Nelson, Alex Travesset
Physics - All Scholarship
We propose and analyze an effective free energy describing the physics of disclination defects in particle arrays constrained to move on an arbitrary two-dimensional surface. At finite temperature the physics of interacting disclinations is mapped to a Laplacian Sine-Gordon Hamiltonian suitable for numerical simulations. We then specialize to the case of a spherical crystal at zero temperature. The ground state is analyzed as a function of the ratio of the defect core energy to the Young's modulus. We argue that the core energy contribution becomes less and less important in the limit R >> a, where R is the radius of …
Dual Function Euv Multilayer Mirrors For The Image Mission, David D. Allred, R. Steven Turley, Matthew B. Squires
Dual Function Euv Multilayer Mirrors For The Image Mission, David D. Allred, R. Steven Turley, Matthew B. Squires
Faculty Publications
We have developed a new family of EUV multilayer mirror coatings using uranium. Using this approach we have coated a set of six mirrors for the EUV Imager, a component of the IMAGE mission. This mission is a Medium Explorer (MIDEX) program, which is scheduled for launch early in 2000. The EUV Imager will study the distribution of He+ in the Earth's plasmasphere by detecting its resonantly scattered emission at 30.4 nm (41 eV) and will produce images of the structure and dynamics of the cold plasma on a global scale. There is, however, a bright at 58.4 nm (21 …
Selective Excitation And Thermal Quenching Of The Yellow Luminescence Of Gan, John S. Colton, P. Y. Yu, K. L. Teo, E. R. Weber, P. Perlin, I. Grzegory, K. Uchida
Selective Excitation And Thermal Quenching Of The Yellow Luminescence Of Gan, John S. Colton, P. Y. Yu, K. L. Teo, E. R. Weber, P. Perlin, I. Grzegory, K. Uchida
Faculty Publications
We report the observation of narrower structures in the yellow luminescence of bulk and thin-film n-type GaN, using the technique of selective excitation. These fine structures exhibit thermal quenching associated with an activated behavior. We attribute these fine structures to phonons and electronic excitations of a shallow donor-deep acceptor complex, and determine its activation energy for delocalization. Our results suggest that in addition to distant donor-acceptor pairs, the yellow luminescence can also involve emission complexes of shallow donors and deep acceptors.
Electron Injection By Dephasing Electrons With Laser Fields, E. Dodd, J.K. Kim, Donald P. Umstadter
Electron Injection By Dephasing Electrons With Laser Fields, E. Dodd, J.K. Kim, Donald P. Umstadter
Donald Umstadter Publications
The authors seek to review injection concepts for plasma based acceleration. It is shown that regardless of injection mechanism, resultant beams will be similar due to wave structure. Also, most schemes employ the same basic processes, namely the dephasing of electrons by laser fields, and can thus be analyzed with similar approaches.
Acceleration Of Electrons In A Self-Modulated Laser Wakefield, Shouyuan Chen, M. Krishnan, Anatoly Maksimchuk, Donald P. Umstadter
Acceleration Of Electrons In A Self-Modulated Laser Wakefield, Shouyuan Chen, M. Krishnan, Anatoly Maksimchuk, Donald P. Umstadter
Donald Umstadter Publications
Acceleration of electrons in a self-modulated laser-wakefield is investigated. The generated electron beam is oberved to have a multi-component beam profile and its energy distribution undergoes discrete transitions as the conditions are varied. These features can be explained by simple simulations of electron propagation in a 3-D plasma wave.