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CreatorTitleDescriptionSubjectDate
176 Vardeny, Zeev Valentine; Nahata, AjayThermal emission from metallic films perforated with subwavelength hole arraysThis report presents an overview of our study on the optical transmission and thermal light emission properties of subwavelength hole arrays fabricated in a square lattice with 4 um periodicity. The structures were fabricated in thin aluminum (Al) films on silicon (Si) substrates using conventional ...2008
177 Gondolo, PaoloCosmic ray positron excess and neutralino dark matterUsing a new instrument, the HEAT Collaboration has confirmed the excess of cosmic ray positrons that they first detected in 1994. We explore the possibility that this excess is due to the annihilation of neutralino dark matter in the galactic halo. We confirm that neutralino annihilation can produ...Neutralinos; Supersymmetric models; Positron flux; Annihilations2002-02
178 DeTar, CarletonHadronic deformation energy. I. Quark-antiquark separationThe MIT bag model for hadrons is treated in the static cavity approximation in three dimensions with a definite quark number. The energy of the system is computed to second order in the gluon coupling. A constrained variational method is described which permits the calculation of the energy as a f...Bag models; Quark bag; Deformation energy; Antiquarks; Gluon coupling; Quark energies; Gluon energies1978-01
179 Ailion, David Charles109Ag NMR investigation of atomic motions in the incommensurate and paraelectric phases of proustite (Ag3AsS3)109Ag NMR line shape, T1 , Hahn spin echo, and Carr-Purcell-Meiboom-Gill ~CPMG! spin-echo measurements were performed in proustite (Ag3AsS3) between 420 and 47 K in order to understand the role of atomic motions in phase transitions in a system containing an incommensurate phase. These measurements ...NMR; Atomic motion; Proustitie; Phase transitions; Line shape2000
180 DeTar, CarletonEquation of state and QCD transition at finite temperatureWe calculate the equation of state in 2 + 1 flavor QCD at finite temperature with physical strange quark mass and almost physical light quark masses using lattices with temporal extent Nr = 8. Calculations have been performed with two different improved staggered fermion actions, the asqtad and p4 a...Deconfinement; Chiral symmetry; Staggered fermions; Phase transitions; Polyakov loop2009-07
181 Wu, Yong-ShiMultiparticle quantum mechanics obeying fractional statisticsWe obtain the rule governing many-body wave functions for particles obeying fractional statistics in two (space) dimensions. It generalizes and continuously interpolates the usual symmetrization and antisymmetrization. Quantum mechanics of more than two particles is discussed and some new features a...Multiparticle quantum mechanics; Fractional statistics1984-07
182 Rogachev, AndreyEnhancing superconductivity: magnetic impurities and their quenching by magnetic fieldsMagnetic fields and magnetic impurities are each known to suppress superconductivity. However, as the field quenches (i.e. polarizes) the impurities, rich consequences, including field-enhanced superconductivity, can emerge when both effects are present. For the case of superconducting wires and th...Thermal phase slippage; Coulomb blockade2006-09-01
183 Vardeny, Zeev ValentineExcitation dynamics in single molecular crystals of α-hexathiophene from femtosecond to millisecondWe identify odd- and even-parity states and measure transient photomodulation spectra of Frenkel excitons in a-hexathiophene single crystals. The lowest Frenkel excitons are characterized by a stimulated emission band at ~2 eV and an absorption band at 1.3 eV. Intramolecular internal conversion go...Excitation dynamics; alpha-hexathiophene; Frenkel excitons; pi-conjugated polymers; Photoexcitation2001-04
184 Vardeny, Zeev ValentineLasing and stimulated emission in ∏-conjugated polymersRecent studies of lasing and stimulated emission in luminescent -conjugated polymers performed by our group are presented. Optical properties of cylindrical high- polymer microcavities are discussed. The emission spectra of plastic microring and microdisk lasers are measured and analyzed. Light-emi...Lasing; Stimulated emission; pi-conjugated polymers; Microcavities; Polymer lasers2000-01
185 Sokolsky, PierreBackward production in π-p→pπ+π-π- at 8 GeV/c*We have studied backward baryon and meson production in π'p → pπ+pπ +π-π- at 8.0 GeV/c using a streamer chamber triggered by the detection of a fast forward proton. Our data sample (1227 events) displays prominent N*p and N*f quasi-two-body production. These states are investigated with rega...1976-01
186 Williams, Clayton C.Single electron tunneling force spectroscopy of an individual electronic state in a non-conducting surfaceA tunneling spectroscopy technique to measure the energy level of an electronic state in a completely nonconducting surface is demonstrated. Spectroscopy is performed by electrostatic force detection of single-electron tunneling between a scanning probe and the state as a function of an applied vo...Tunneling; Spectroscopy; Single electron; Scanning tunneling microscope2006
187 Wu, Yong-ShiDynamics of giant-gravitons in the LLM geometry and the fractional quantum Hall effectThe LLM's 1/2 BPS solutions of IIB supergravity are known to be closely related to the integer quantum Hall droplets with filling factor v = 1, and the giant gravitons in the LLM geometry behave like the quasi-holes in those droplets. In this paper we consider how the fractional quantum Hall effect ...2006
188 Gondolo, PaoloEffects of the Sagittarius dwarf tidal stream on dark matter detectorsThe Sagittarius dwarf tidal stream may be showering dark matter onto the solar neighborhood, which can change the results and interpretation of direct detection searches for weakly interacting massive particles (WIMPs). Stars in the stream may already have been detected in the solar neighborhood, an...Sagittarius dwarf galaxy; Sgr stream; WIMP; Weakly interacting massive particles2004-03
189 Vardeny, Zeev ValentineAbsorption studies of charged excitations in α-sexithiopheneWe present photoexcitation studies of vacuum deposited neutral films of α,ω-substituted sexithiophene (α-6T) using photoinduced absorption (PA) and PAdetected magnetic resonance spectroscopy (PADMR). We find evidence for photoinduced polarons having spin 1/2, with two absorption bands at 0.80...alpha- sexithiophene; Charged excitations; Photoexcitation; Photoinduced absorption1996
190 Sokolsky, PierreSearch for new particles at the alternating-gradient-synchrotron beam dumpThis paper presents results of a beam-dump experiment performed at the Brookhaven alternating-gradient synchrotron to search for prompt sources of neutrinos and axionlike particles. We observe no excess of vµ or events, and no excess in neutral-current events over that expected from neutrinos from ...1979-05
191 Wu, Yong-ShiAnyons on a torus: braid group, Aharonov-Bohm period, and numerical studyWe present a careful construction of anyons on a torus starting with the braid-group analysis. The rules of Wen, Dagotto, and Fradkin for putting anyons on a torus are reproduced with some minor improvements. The existence of noncontractible loops leads to braid-group representations characterized n...Braid group; Magnetic flux1991-05
192 Vardeny, Zeev ValentineCooperative emission in ∏-conjugated polymer thin filmsPicosecond dynamics of exciton emission and absorption have been studied in neat thin films of a variety of poly (phenylene vinylene) derivatives. We found that the stimulated emission band of 120 nm width and ~1 ns duration, which is observed at low exciton density n, collapses at n > 1017 cm-3 int...Pi-conjugated polymers; Poly (phenylene vinylene) derivatives; PPV derivatives; Cooperative emission1997-01
193 Gondolo, PaoloNeutralino with the right cold dark matter abundance in (almost) any supersymmetric modelWe consider nonstandard cosmological models in which the late decay of a scalar field Ø reheats the Universe to a low reheating temperature, between 5 MeV and the standard freeze-out temperature of neutralinos of mass mx. We point out that in these models all neutralinos with standard density Ώstd...Neutralinos; Reheating temperature2006-07
194 Vardeny, Zeev ValentinePhotoinduced absorption spectra in α-GeH and α-Si:HMeasurements of steady-state photoinduced absorption in α-Ge:H and α-Si:H were extended to cover the energy range from 0.25 to 1.9 eV. The subgap photoinduced-absorption bands in both materials are interpreted in terms of four kinds of optical transitions of photogenerated carriers from traps in ...Photoinduced absorption; in a-GeH; a-Si:H; Amorphous germanium; Amorphous silicon1984-07
195 Boehme, ChristophDiffusion of hydrogen and deuterium in stack systems of SixNyHz/SixNyDz and crystalline SiH/D-, N-H/D- and Si-H/D-bond density changes were investigated in stacks consisting of a Cz-Si substrate, a thin layer of SiC>2, amorphous deuterated silicon nitride as well as amorphous hydrogenated silicon nitride in order to see if the post deposition anneal of a-SixNyHz layers on crystalline sil...Hydrogenated silicon nitride; Anneal process2000
196 Lupton, John MarkRoom-temperature exciton storage in elongated semiconductor nanocrystalsThe excited state of colloidal nanoheterostructures consisting of a spherical CdSe nanocrystal with an epitaxially attached CdS rod can be perturbed effectively by electric fields. Field-induced fluorescence quenching coincides with a conversion of the excited state species from the bright exciton ...Exciton storage; Colloidal nanoheterostructures; CdSe nanocrystal2007-01
197 Vardeny, Zeev ValentineEvolution of excitons and polarons in polythiophene from femtoseconds to millisecondsWe have studied the photoexcitation dynamics in electrochemically polymerized polythiophene thin films using transient photomodulation spectroscopy measured from 100 fs to 20 ms in the spectral range from 0.25 to 2.2 eV, and by the novel technique of absorption-detected magnetic resonance (ADMR). ...Femtoseconds; Milliseconds; Photoexcitation dynamics1992-07
198 Vardeny, Zeev ValentinePhotogeneration and recombination processes of neutral and charged excitations in films of a ladder-type poly(para-phenylene)We introduce a version of the cw photomodulation technique, measured far from the steady state, for obtaining the quantum efficiency, η, of long-lived photoexcitations in p-conjugated polymers. We apply this technique to films of a ladder-type poly(para-phenylene) [mLPPP] for studying the photoge...Photogeneration; Recombination process; Neutral excitations; Charged excitations; Ladder-type poly(para-phenylene)1999-08
199 Sokolsky, PierreMeasurement of the flux of ultrahigh energy cosmic rays from monocular observations by the High Resolution Fly's Eye experimentWe have measured the cosmic ray spectrum above 1017.2 eV using the two air-fluorescence detectors of the High Resolution Fly's Eye observatory operating in monocular mode.We describe the detector, phototube, and atmospheric calibrations, as well as the analysis techniques for the two detectors.We fi...Extensive air showers; Fluorescence; Energy spectrum2004-04
200 Gondolo, PaoloGamma-ray summary reportThis paper reviews the field of gamma-ray astronomy and describes future experiments and prospects for advances in fundamental physics and high-energy astrophysics through gamma-ray measurements. We concentrate on recent progress in the understanding of active galaxies, and the use of these sources ...EGRET; GLAST; VERITAS2001
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