251 - 275 of 924
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251 Mishchenko, EugeneZero-bias anomaly in two-dimensional electron layers and multiwall nanotubesThe zero-bias anomaly in the dependence of the tunneling density of states n (e) on the energy e of the tunneling particle for two- and one-dimensional multilayered structures is studied. We show that for a ballistic two-dimensional (2D) system the first-order interaction correction to density of s...Spin-orbit coupling; Coulomb interaction2002-05
252 DeTar, CarletonLight quark spectrum with improved gauge and fermion actionsWe report on a study of the light quark spectrum using an improved gauge action and both Kogut-Susskind and Naik quark actions. We have studied six different lattice spacings, corresponding to plaquette couplings ranging from 6.8 to 7.9, with five to six quark masses per coupling. We compare the t...Quark spectrum; Kogut-Susskind quarks; Naik quarks1998-04
253 Wu, Yong-ShiQuantum phase transition in a multicomponent Bose-Einstein condensate in optical latticesWe present a general lattice model for a multicomponent atomic Bose-Einstein system in an optical lattice. Using the model, we analytically study the quantum phase transition between the Mott insulator and a superfluid. A mean-field theory is developed from the Mott-insulator ground state. When the...Quantum phase transitions; Optical lattices; Bose-Einstein condensation; Boson-Hubbard model; Superfluids2003-01
254 Symko, Orest GeorgeTemperature dependence of the order parameter in a dilute AgMn spin glassThe magnetization of a dilute AgMn spin glass containing 150 ppm Mn has been measured over the temperature range from 20 mK to 2 K in an applied field of 0.9 Oe, using a SQUID magnetometer. A comparison of the measured magnetization with numerical calculations of the magnetization based on the Mean ...AgMn spin glass; Mean random field; MRF; Temperature dependence; Order parameter; RKKY interactions1982
255 Vardeny, Zeev ValentineMagnetic field effects in ∏-conjugated polymer-fullerene blends: evidence for multiple componentsWe studied magnetoconductance (MC) and magnetoelectroluminescence (MEL) in organic diodes from blends of ∏-conjugated polymers and fullerenes at various concentrations, c. The MC response is composed of several components that depend on the applied bias voltage and c. A dominant positive low-field...pi-conjugated polymers; Fullerene blends; Magnetic field effects; Magnetoconductance; Magnetoelectroluminescence; MC; MEL; Organic magnetoresistance; OMAR; Organic diodes2008-12
256 Vardeny, Zeev ValentinePhotoexcitation dynamics in regioregular and regiorandom polythiophene filmsUsing a variety of optical probes techniques we studied the photoexcitation dynamics in thin films of poly-3-hexyl thiophene with regioregular order that forms lamellae structures with increased interchain interaction, as well as regiorandom order that keeps a chainlike morphology. In regiorandom fi...Photoexcitation dynamics; Regio-regular; Regio-random; Polythiophene films2001-11
257 Wu, Yong-ShiMultisheet configuration space and fractional quantum statisticsWe show that if one uses a multisheet configuration space for a system of identical particles, then fractional quantum statistics in two dimensions can be geometrically characterized as a topological quantum number for going from one sheet to the next. Furthermore, the spectrum of such a g-sheet s...1992-05
258 Williams, Clayton C.High-resolution photothermal laser probeAn advance in photothermal imaging is described. A photothermal laser probe is presented that operates at a frequency of 1 GHz. At this frequency the spacial resolution is limited only by the optical spot size of the probe beam. The photothermal sensitivity of the probe is 1.2 X 10-4 degrees Celsiu...Laser probes1985
259 Vardeny, Zeev ValentineRandom lasing in human tissuesA random collection of scatterers in a gain medium can produce coherent laser emission lines dubbed "random lasing." We show that biological tissues, including human tissues, can support coherent random lasing when infiltrated with a concentrated laser dye solution. To extract a typical random reson...Random lasing; Gain medium; Human tissues; Malignant tissues2004
260 Wu, Yong-ShiQuiver matrix mechanics for IIB string theory (II): generic dual tori, fractional matrix membrane and SL(2, Z) dualityWith the deconstruction technique, the geometric information of a torus can be encoded in a sequence of orbifolds. By studying the Matrix Theory on these orbifolds as quiver mechanics, we present a formulation that (de)constructs the torus of generic shape on which Matrix Theory is "compactified". T...2005-02
261 Symko, Orest GeorgeSpin-glass transition of a dilute Ag-Mn alloy in a magnetic fieldThe spin-glass state in a magnetic field is studied in a very dilute Ag-Mn sample containing 150 ppm of Mn. The field-cooled magnetization of this system is investigated over temperatures ranging from 4 down to 0.01 K in magnetic fields from 932 to 1 Oe. Scaling is observed in the nonlinear suscepti...Spin-glass transition; Spin-glass state; Ag-Mn alloy; Silver-manganese alloy1986-01
262 DeTar, CarletonLattice calculation of 1-+ hybrid mesons with improved Kogut-Susskind fermionsWe report on a lattice determination of the mass of the exotic 1-+ hybrid meson using an improved Kogut-Susskind action. Results from both quenched and dynamical quark simulations are presented. We also compare with earlier results using Wilson quarks at heavier quark masses. The results on lattice...Staggered quarks; Kogut-Susskind fermions2003-10
263 Vardeny, Zeev ValentineLaser action in polydialkylfluorene films: influence of low-temperature thermal treatmentWe have used a variety of optical probes to investigate the changes occurring upon low-temperature thermal treatment to the emissive properties of dialkyl substituted polyfluorene thin films. We found that the low-temperature-driven morphological changes involving aggregates formation, which are ob...Laser action; Polydialkylfluorene films; pi-conjugated polymers; Thermal treatment1999
264 Dawson, KyleRadiation tolerance of fully-depleted P-channel CCDs designed for the SNAP satelliteThick, fully depleted p-channel charge-coupled devices (CCDs) have been developed at the Lawrence Berkeley National Laboratory (LBNL). These CCDs have several advantages over conventional thin, n-channel CCDs, including enhanced quantum efficiency and reduced fringing at near-infrared wavelengths an...P-Channel CCDs; SNAP satellite; Space-based telescopes2008-06
265 Gondolo, PaoloAGAPEROS: searching for microlensing in the LMC with the pixel method. I. Data treatment and pixel light curves productionRecent surveys monitoring millions of light curves of resolved stars in the LMC have discovered several microlensing events. Unresolved stars could however signi _x000C_cantly contribute to the microlensing rate towards the LMC. Monitoring pixels, as opposed to individual stars, should be able to ...Data analysis techniques; Halo; Galaxies; Gravitational lensing; Pixel method; Large Magellanic Cloud; LMC1999
266 Gerton, JordanDipolar relaxation collisions in magnetically trapped 7LiWe report the measurement of the rate constant for dipolar relaxation from the (F=2, mF=2) hyperfine state of 7Li. The atoms are confined in a permanent magnet trap at a field of 10^3 G. The measured value of (1.05±0.10)X10^-14 cm3/s agrees well with theory. Additionally, we determine an upper bo...1999-02
267 Symko, Orest GeorgeTunneling studies of mesoscopic all-NBN junctionsA scanning tunneling microscope (STM) was used to position a NbN tip near a NbN thin film sputtered on a Si substrate. Measurements at 4.2 K clearly show an energy gap of 5.0 mV. The Coulomb blockade of tunneling and the Coulomb staircase, formed by single-electron charging of the central electrod...All-NbN junctions; NbN1993-03
268 Vardeny, Zeev Valentine; Symko, Orest GeorgeQuasiparticle relaxation in high-Tc superconductorRecent measurements by Eesley et al. [1] of transient reflectivity in superconducting Tl2Ba2Ca2Cu30io were interpreted as evidence for order-parameter relaxation in the vicinity of Tc, which was analyzed in terms of BCS weak coupling for ?(r)/?(0). In this Comment we question this interpretation ...Quasiparticle relaxation1991
269 Gondolo, PaoloStellar orbit constraints on neutralino annihilation at the galactic centerDark matter annihilation has been proposed to explain the TeV gamma rays observed from the Galactic Center. We study constraints on this hypothesis coming from the mass profile around the Galactic Center measured by observing stellar dynamics. We show that for several proposed WIMP candidates, the...Neutralinos; Annihilation2006-09
270 Vardeny, Zeev ValentineUltrafast spectroscopy of excitons in single-walled carbon nanotubesWe studied the femtosecond dynamics of photoexcitations in films containing semiconducting and metallic single-walled carbon nanotubes (SWNTs), using various pump-probe wavelengths and intensities.We found that confined excitons and charge carriers with subpicosecond dynamics dominate the ultrafas...Ultrafast spectroscopy; Excitons; Single-walled carbon nanotubes; SWNT2004-01
271 Gondolo, PaoloDetectability of the Sgr dwarf leading tidal stream with Auger, EUSO, or OWLWe point out that if heavy metastable particles composing the dark matter of our galaxy are responsible for the ultrahigh energy cosmic rays (UHECR) then the leading tidal stream of the Sagittarius dwarf galaxy could be detected through UHECR. The signal would be an anisotropy in the UHECR flux sma...Sagittarius dwarf galaxy; Sgr stream; anisotropy2004-07
272 Sokolsky, PierreFirst observation of the Greisen-Zatsepin-Kuzmin suppressionThe High Resolution Fly's Eye (HiRes) experiment has observed the Greisen-Zatsepin-Kuzmin suppression (called the GZK cutoff) with a statistical significance of five standard deviations. HiRes' measurement of the flux of ultrahigh energy cosmic rays shows a sharp suppression at an energy of 6 x 10^1...Extensive air showers; Suppression; Energy spectrum; Fluorescence; GZK cutoff2008-03
273 Gondolo, PaoloAGAPE: andromeda gravitational amplification pixel experimentThe aim of the AGAPE (Andromeda Gravitational Ampli_x000C_cation Pixel Experiment), experiment which has been _x000C_rst proposed in June 1992 is to examine the distribution of massive astrophysical compact halo objects ((MACHO's) which possibly are in the galactic haloes and which could account for...AGAPE; Andromeda Gravitational Amplification Pixel Experiment; Microlensing; MACHO; Massive compact halo objects1997
274 Williams, Clayton C.High resolution thermal microscopyA new high resolution thermal microscope has been demonstrated capable of imaging thermal fields with sub 1000 angstom resolution. It is based upon a non-contacting near field thermal probe. The thermal probe consists of a thermocouple sensor on the end of a tip with sub 1000 angstrom dimensions. Th...1986
275 Sokolsky, PierreObservation of the reaction νµ + p →νµ + p+We have observed the elastic neutral - current reaction vµ +p→vµ +p and compared it to the quasielastic reaction vµ +n→µ +p. We have measured the ratio of the two reactions to be 0.23 ± 0.09.1976-07
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