UScholar Works
 
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CreatorTitleDescriptionSubjectDate
351 DeTar, CarletonThermodynamic properties of the gluon plasmaWe calculate the energy density, pressure, and speed of sound in the deconfined phase of lattice SU(3) gauge theory at finite temperature for lattices of temporal size N,=4, 6, and 8. We compare our results with perturbative QCD at high temperature and with a simple phenomenological model. We also p...Hadronic matter; Energy density; Gluon plasma; Phase transitions1987-01
352 DeTar, CarletonSemileptonic decays of heavy mesons with the fat clover actionWe are studying a variety of semileptonic decays of heavy-light mesons in an effort to improve the determination of the heavy-quark Standard-Model CKM matrix elements. Our fermion action is a novel, improved "fat" clover action that promises to reduce problems with exceptional configurations. Dynami...Semileptonic decay; Decay constants; Staggered quarks; Fat-clover valence quarks2000-04
353 Boehme, ChristophH loss mechanism during anneal of silicon nitride: chemical dissociationRemote plasma enhanced chemical vapor deposited silicon nitride (SixNyHz), produced at high ammonia to silane flow rates (ammonia rich) shows a reduction of hydrogen during rapid thermal anneal at temperatures that exceed the deposition temperature. This H release could be either due to a ‘‘slow...Anneal2000
354 Lupton, John MarkMonitoring surface charge migration in the spectral dynamics of single CdSe∕CdS nanodot/nanorod heterostructuresSpherical CdSe nanocrystals capped by a CdS rod-like shell exhibit interesting spectral dynamics on the single particle level. Spectral boxcar averaging reveals a high degree of correlation between the emission energy, spectral linewidth, phonon coupling strength, and emission intensity of the singl...Surface charge migration; Spectral dynamics; CdSe; CdS; Nanodot; Nanorod2005-11
355 Bromley, Benjamin C.Periodic standing-wave approzimation: post-Minkowski computationsThe periodic standing-wave method studies circular orbits of compact objects coupled to helically symmetric standing-wave gravitational fields. From this solution an approximation is extracted for the strong field, slowly inspiralling motion of black holes and binary stars. Previous work on this m...Black holes; Binary stars; Gravitational waves2007
356 DeTar, CarletonLattice results for the decay constant of heavy-light vector mesonsWe compute the leptonic decay constants of heavy-light vector mesons in the quenched approximation. The reliability of lattice computations for heavy quarks is checked by comparing the ratio of vector to pseudoscalar decay constant with the prediction of heavy quark effective theory in the limit o...Heavy quark effective theory; Wilson quarks2001-12
357 Williams, Clayton C.Shear force microscopy with capacitance detection for near-field scanning optical microscopyShear force microscopy is very useful for distance regulation in near-field scanning optical microscopy (NSOM). However, the optical method used to detect the shear force can cause problems when imaging photosensitive materials, i.e., the shear force detection beam can optically pump the sample. We ...Shear force microscopy; Atom force microscope; AFM; Capacitance sensing1995
358 Boehme, ChristophObservation of precursor pair formation of recombining charge carriersAn experiment is presented which allows the observation of charge-carrier pair formation that precedes electronic transitions such as spin-dependent recombination or spin-dependent transport. It is based on an electrically detected magnetic-resonance-induced rotary echo sequence. The experimental de...Charge carriers2009-07
359 Mattis, Daniel C.Two-dimensional Ising model in a finite magnetic fieldWe present the results of numerical calculations giving accurate estimates of the magnetization of the two-dimensional Ising model on a square lattice. Moreover, we argue that these results are strict lower bounds to the correct magnetization M(H, T). The estimates are obtained by dividing the infin...Magnetization1970-10
360 Mattis, Daniel C.Existence of two phase transitions in Hubbard modelWe solve the Hubbard model, for one electron per atom in a simple cubic structure, using one-particle Green's functions. We determine the accuracy of this calculation to be good by comparison with an exact solution by Lieb and Wu of a one-dimensional limiting case.Critical temperature1969-12
361 Vardeny, Zeev ValentineStates in the gap of doped and undoped a-Si:H studied by the photomodulation spectroscopyThe steady state photomodulation spectrum, its temperature and excitation intensity dependences have been studied in phosphorous doped and undoped a-Si:H. The spectra are analyzed in terms of photocarriers trapped in band-tail states and dangling bonds (DB) defects in undoped samples and impurities ...Doped a-Si:H; Undoped a-Si:H; Amorphous silicon; Photomodulation spectroscopy; Mobility gap; Steady state photomodulation spectrum1987
362 DeTar, CarletonQCD thermodynamics with two flavors of Wilson quarks at Nt=6We report on a study of hadron thermodynamics with two flavors of Wilson quarks on 123 X6 lattices. We have studied the crossover between the high- and low-temperature regimes for three values of the hopping parameter, K=0. 16, 0.17, and 0.18. At each of these values of K we have carried out spect...Wilson quarks; Staggered quarks; Chiral symmetry; Phase transitions1992-11
363 Gondolo, PaoloDaily modulation due to channeling in direct dark matter crystalline detectorsThe channeling of the ion recoiling after a collision with a weakly interacting massive particle (WIMP) in direct dark matter crystalline detectors produces a larger scintillation or ionization signal than otherwise expected. Channeling is a directional effect, which depends on the velocity distrib...2011
364 Mattis, Daniel C.Theory of electronic switching effect as a cooperative phenomenonA modified form of Zener tunneling theory, in which we assume that the tunneling barrier is a decreasing collective function of electronic excitation, is shown to imply insulator- to-metal switching characteristics similar to those reported by Ovshinsky for glass film devices. In addition, our І-V ...Electronic switching; Negative resistance1969-05
365 Lupton, John MarkFrequency up-conversion as a temperature probe of organic opto-electronic devicesFrequency up-conversion is demonstrated in a polyfluorene-based conjugated polymer. Up-converted emission is observed upon excitation to the red of the 0-0 luminescence band. The emission intensity depends strongly on temperature and provides an accurate probe of the operating temperature of organic...Frequency up-conversion; Organic opto-electronic devices2002
366 DeTar, Carletonf B for various actions: approaching the continuum limit with dynamical fermionsWe present results for pseudoscalar decay constants of heavy-light mesons using both quenched and Nf = 2 dynamical fermion configurations. A variety of fermion actions is investigated: Wilson, nonperturbative clover, and fat-link clover. For heavy quarks the Fermilab formalism is applied. In the q...Decay constants; Wilson fermions2001-03
367 Vardeny, Zeev ValentinePhotogeneration action spectroscopy of neutral and charged excitations in films of ladder-type poly(para-phenylene)The photogeneration quantum efficiency action spectra of long-lived neutral and charged excitations in films of a ladder-type poly(para-phenylene) were measured. We found that both triplet and polaron action spectra show, in addition to a step function increase at the optical gap, a monotonic rise a...Photogeneration; Neutral excitations; Charged excitations; pi-conjugated polymers; Transient spectroscopy1999-04
368 DeTar, CarletonBaryon density correlations in high temperature hadronic matterAs part of an ongoing effort to characterize the high temperature phase of QCD, in a numerical simulation using the staggered fermion scheme, we measure the quark baryon density in the vicinity of a fixed test quark at high temperature and compare it with similar measurements at low temperature and ...Baryon density; Staggered fermions; Quark plasma1994-06
369 DeTar, CarletonVisualization of semileptonic form factors from lattice QCDComparisons of lattice-QCD calculations of semileptonic form factors with experimental measurements often display two sets of points, one each for lattice QCD and experiment. Here we propose to display the output of a lattice-QCD analysis as a curve and error band. This is justified, because lattice...Semileptonic decay2009-08
370 Mattis, Daniel C.Comment on "Ground-state properties of a spin-1 antiferromagnetic chainBotet and Jullien [Phys. Rev. B 27, 613 (1983)] and Botet, Jullien, and Kolb [Phys. Rev. B 28, 3914 (1983)] performed a finite-size scaling analysis of the spin-1 antiferromagnetic Heisenberg-Ising chain. Their work was criticized by Bonner and Mtiller [Phys. Rev. B 29, 5216 (1984)] on the grounds...Antiferromagnets; Ground-state; Ising chain; Energy gap1985-04
371 Sokolsky, PierreEffect of clouds on apertures of space-based air fluorescence detectorsSpace-based ultra-high-energy cosmic ray detectors observe fluorescence light from extensive air showers produced by these particles in the troposphere. Clouds can scatter and absorb this light and produce systematic errors in energy determination and spectrum normalization. We study the possibilit...Fluorescence; Cloud detection; Extensive air showers2004-01
372 Vardeny, Zeev ValentineUniversal properties of quasi-one-dimensional excitons in semiconducting single-walled carbon nanotubes and ∏-conjugated polymersThe nature of the primary photoexcitations in semiconducting single-walled carbon nanotubes (S-SWCNTs) is of strong current interest. We have studied the emission spectra of S-SWCNTs and two different rr-conjugated polymers in solutions and films, and have also performed ultrafast pump-probe spectr...Carbon nanotubes; pi-conjugated polymers; SWCNT; Photoexcitation; Optoelectronic properties; Quasi-one-dimensional2006
373 Gondolo, PaoloClumpy neutralino dark matterWe investigate the possibility to detect neutralino dark matter in a scenario in which the galactic dark halo is clumpy. We find that under customary assumptions on various astrophysical parameters, the antiproton and continuum γ-ray signals from neutralino annihilation in the halo put the strong...Neutralinos; Clumpiness1999-01
374 Vardeny, Zeev ValentineOptical probes of excited states in poly (p-phenylenevinylene)We have studied electronic excited states in films of poly(p-phenylenevinylene) using picosecond transient and cw photomodulation, photoluminescence, and their excitation spectra, as well as electroabsorption spectroscopy. We have determined all the important energy levels of singlet excitons with...Poly (p-phenylenevinylene); Photoexcitation1994-01
375 Symko, Orest GeorgeSpatial Fourier transform method for evaluating SQUID gradiometersA simple method of measuring the spatial transfer function of a gradiometer, consisting of a flux transformer coupled to a SQUID, is presented and it is compared with theoretical predictions. Based, on this approach, a new method of reporting a gradiometer's performance is proposed; the rejection fa...Spatial Fourier transform; SQUID gradiometers; Evaluation; Spatial transfer function1987
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