UScholar Works
 
Filters: Department: "Physics" Collection: "ir_uspace"
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CreatorTitleDescriptionSubjectDate
1 Sokolsky, Pierre; Cassiday, George L.Evidence for a high-energy cosmic-ray spectrum cutoffWe report a measurement of the ultrahigh-energy cosmic-ray spectrum using an atmospheric fluorescence technique for extensive-air-shower detection. The differential spectrum between 0.1 and 10 EeV (1 EeV = 10^18 eV) is well fitted by a power law with slope 2.94 ±0.02. Above 10 EeV evidence is prese...Energy spectrum; Extensive air showers; Spectral cutoff1985-04
2 Williams, Clayton C.Direct imaging of SiO2 thickness variation on Si using modified atomic force microscopeFabrication techniques of metal-oxide-semiconductor ~(MOS) transistors have been improved very rapidly during the last several decades. With this trend, scaling down of MOS transistors is necessary to improve the speed of circuits and the packing density of discrete devices. Both lateral and vertic...Silicon dioxide; Oxide layer; Phosphorus ions; Oxide capacitance; Dopant profile1996-03-01
3 Williams, Clayton C.Mapping of mobile charges on insulator surfaces with the electrostatic force microscopeMigration of surface ions in lateral fields on insulator surfaces may modify the electrical characteristics of underlying semiconductor structures causing device instabilities. A high sensitivity electrostatic force microscope is used to image the movement and spatial distribution of surface ions on...Insulator surfaces; Surface ions; Electrostatic force microscope1993
4 Mishchenko, Eugene; Raikh, Mikhail E.Electrostatics of straight and bent single-walled carbon nanotubesResponse of a single-walled carbon nanotube to external electric field, F, is calculated analytically within the classical electrostatics. Field-induced charge density distribution is approximately linear along the axis of a metallic nanotube and depends rather weakly, as ln(h/ r), on the nanotube...Electrostatics2006-10
5 Wu, Yong-ShiTransitions between the quantum Hall states and insulators induced by periodic potentialsTransitions between two quantum Hall states or between a quantum Hall state and a Mott insulator induced by periodic potentials are studied in the 1 /TV expansion. The transitions are found to be continuous in the large-TV limit and are described by a critical point that depends on a real parameter ...Periodic potentials; Insulators1993-03
6 Rogachev, AndreyObservation of shot noise in phosphorescent organic light-emitting diodesWe employed a cross correlation method to study current noise in phosphorescent organic light-emitting diodes. The noise spectra revealed two frequency-dependent components. The first component displays 1/ f 1.3 dependence and correlates with the light emission of the devices. The second component i...2014-01-01
7 Wu, Yong-ShiQuantum dynamics and statistics of vortices in two-dimensional superfluidsThe phase change of the wave function of a superfluid film as a vortex moves around a closed path counts the number of superfluid particles enclosed by that path. This result is used to investigate whether such vortices obey "fractional statistics." We conclude that this is not the case in compress...Superfluid films; Vortices; Fractional statistics1985-12
8 Vardeny, Zeev ValentineStudies of polymer microring lasers subject to uniaxial stressThe emission spectra of microring lasers fabricated from ∏-conjugated polymer films casted on nylon microfibers with diameters in the range of 35-90 µm were studied upon application of uniaxial stress with strain up to ~12%. The laser emission spectra substantially change with the applied stress,...pi-conjugated polymers; Microring lasers; Uniaxial stress; DOO-PPV2007
9 Mattis, Daniel C.Theory of ferromagnetism in carbon foamAn explanation is proposed for spontaneous magnetism in the material, "carbon nanofoam," in terms of random ferrimagnetism. Wherever a carbon nanotube branches out, an electron trap is created at the junction. Electrons occupying neighboring junctions align their spins antiparallel.Carbon foam; Nanotubes; Nanofoam2005-04
10 Vardeny, Zeev ValentineThe effects of charge injection in single-wall carbon nanotubes studied by charge-induced absorptionWe studied direct charge injection in a heterogeneous film of single-wall carbon nanotubes using the technique of charge-induced absorption. We found that the injected charges screen the excitons in the semiconducting tubes, reducing their binding energy and transferring oscillator strength from the...2011
11 Sokolsky, Pierre; Cassiday, George L.; Kieda, David B.Search for y rays above 10^14 eV from Cygnus X-3 during the June and July 1989 radio outburstsWe have looked for γ-ray emission above 100 TeV from the binary x-ray source Cygnus X-3 during a period of intense radio emission in the summer of 1989. We find no evidence for excess air showers from the direction of the source and the muon content of air showers from this direction is the same as...Cygnus X-3; Radio outbursts; Extensive air showers1989-11
12 Kieda, David B.; Cassiday, George L.; Sokolsky, PierreSearch for γ rays above 1014 eV from Cygnus X-3 during the June and July 1989 radio outburstsWe have looked for γ-ray emission above 100 TeV from the binary x-ray source Cygnus X-3 during a period of intense radio emission in the summer of 1989. We find no evidence for excess air showers from the direction of the source and the muon content of air showers from this direction is the same ...Fly's Eye1989-11
13 Wu, Yong-ShiNear-horizon Virasoro symmetry and the entropy of de Sitter space in any dimensionDe Sitter spacetime is known to have a cosmological horizon that enjoys thermodynamic-like properties similar to those of a black hole horizon. In this note we show that a universal argument can be given for the entropy of de Sitter spacetime in arbitrary dimensions, by generalizing a recent near ho...1999-05
14 Vardeny, Zeev ValentineRecent advances in organic spin-valve devicesOrganic Spintronics has been considered to be the physics and applications of spin polarized electron injection, transport, manipulation and detection in organic diodes by the application of an external magnetic field. The prototype device is the organic spin-valve (OSV), which is based on an organi...Spin-valve devices; Organic Spintronics; Spin polarized carrier injection; OSV2010-02
15 Vardeny, Zeev ValentineSpin and magnetic field effects in organic semiconductor devicesThe authors describe three spin and magnetic field effects in organic semiconductor devices: First, injection, transport and detection of spin-polarised carriers using an organic semiconductor as the spacer layer in a spin-valve structure, yielding low-temperature giant magnetoresistance effects as...Spin effects; Magnetic field effects; MR; OLED; Organic light-emitting diode; Spin-polarised carriers; Spin-dependent exciton formation; Electroluminescent efficiency; pi-conjugated organic semicondutors; OSEC2005
16 Wu, Yong-ShiMott transition in an anyon gasWe introduce and analyze a lattice model of anyons in a periodic potential and an external magnetic field, which exhibits a transition from a Mott insulator to a quantum Hall fluid. The transition is characterized by the anyon statistics a, which can vary between fermions, a = 0, and bosons, ct - 1...Anyon gas; Periodic potentials; Mott transition1993-11
17 Gondolo, PaoloLight dark matter in leptophobic Z' modelsRecent experimental results in direct dark matter detection may be interpreted in terms of a dark matter particle of mass around 10 GeV=c2. We show that the required scenario can be realized with a new dark matter particle charged under an extra Abelian gauge boson Z0 that couples to quarks but not ...2012-01-01
18 Wu, Yong-ShiIntegrable open spin chain in super Yang-Mills and the plane-wave/SYM dualityWe investigate the integrable structures in an N = 2 superconformal Sp(N) Yang-Mills theory with matter, which is dual to an open+closed string system. We restrict ourselves to the BMN operators that correspond to free string states. In the closed string sector, an integrable structure is inherited ...2004-02-01
19 Sokolsky, PierreHighest energy cosmic rays and results from the HiRes experimentThe status of the field of ultrahigh energy cosmic ray physics is summarized, from the point of view of the latest results of the High Resolution Fly's Eye (HiRes) Experiment. HiRes results are presented, and compared with those of the Akeno Giant Air Shower Array (AGASA), plus the Telescope Array ...Fluorescence; Energy spectrum; GZK cutoff; Extensive air showers; Anisotropy2007-11-01
20 Gerton, JordanEffect of magnetic Gd impurities on the superconducting state of amorphous Mo-Ge thin films with different thickness and morphologyWe studied the effect of magnetic doping with Gd atoms on the superconducting properties of amorphous Mo70Ge30 films. We observed that in uniform films deposited on amorphous Ge, the pair-breaking strength per impurity strongly decreases with film thickness initially and saturates at a finite value ...2012-01-01
21 Vardeny, Zeev ValentineExperimental determination of the charge/neutral branching ratio η in the photoexcitation of ∏-conjugated polymers by broadband ultrafast spectroscopyWe demonstrate a long-sought reliable method for determining the important branching ratio η between photogenerated charged polarons and neutral excitons in ∏-conjugated polymer films and solutions, using femtosecond transient photomodulation spectroscopy with broad spectral range from 0.14 to ...pi-conjugated polymers; Charge/neutral branching ratio; Photoexcitation; nu value; Broadband ultrafast spectroscopy2007-02
22 Sokolsky, PierreHighest-energy cosmic raysWhat in the cosmos can possibly be accelerating protons to 1020 electron volts and beyond? And how can they preserve such extreme energies while plowing through the cosmic microwave background on their way to us?Energy spectrum; GZK cutoff; Atmospheric fluorescence1998
23 Sokolsky, PierreObservation of the suppression of the flux of cosmic rays above 4×10^19eVThe energy spectrum of cosmic rays above 2.5 x 10^18 eV, derived from 20 000 events recorded at the Pierre Auger Observatory, is described. The spectral index γ of the particle flux, J∞ E-γ, at energies between 4 x 10^18 eV and 4 x 10^19 eV is 2.69 ± 0.02(stat) ± 0.06(syst), steepening to 4.2 ...Extensive air showers; Energy spectrum; Fluorescence; Suppression2008-08
24 Kieda, David B.; Sokolsky, PierreSearch for > 200 TeV photons from Cygnus X-3 in 1988 and 1989Over a period of 16 months from April 1988 to August 1989, we have monitored the flux of cosmic-ray showers with energies above 2X 101 4 eV. We used a two-level array of scintillators covering an area of 3 X 104 m2. Counters on the surface measure the size and direction of each shower while counters...TeV photons; Cosmic ray showers1990-07
25 Sokolsky, PierreSearch for > 200 TeV photons from Cygnus X-3 in 1988 and 1989Over a period of 16 months from April 1988 to August 1989, we have monitored the flux of cosmic-ray showers with energies above 2X 10^14 eV. We used a two-level array of scintillators covering an area of 3 X 10^4 m2 . Counters on the surface measure the size and direction of each shower while counte...Cygnus X-3; Extensive air showers1990-07
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