UScholar Works
 
Filters: Department: "Physics" Collection: "ir_uspace"
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CreatorTitleDescriptionSubjectDate
1 Gondolo, PaoloDark stars: BegynnelsenThe first phase of stellar evolution in the history of the universe may be Dark Stars, powered by dark matter heating rather than by fusion. Weakly interacting massive particles, which are their own antiparticles, can annihilate and provide an important heat source for the first stars in the univers...Dark stars; WIMP; Weakly interacting massive particles; Annihilations2009
2 Gondolo, PaoloDark Stars: Död och ÅteruppståndelseThe first phase of stellar evolution in the history of the universe may be Dark Stars, powered by dark matter heating rather than by fusion. Weakly interacting massive particles, which are their own antiparticles, can annihilate and provide an important heat source for the first stars in the univers...Dark stars; WIMP; Weakly interacting massive particles2009
3 Gondolo, PaoloDark Stars: the first stars in the universe may be powered by dark matter healingA new line of research on Dark Stars is reviewed, which suggests that the first stars to exist in the universe were powered by dark matter heating rather than by fusion. Weakly Interacting Massive Particles, which may be there own antipartmers, collect inside the first stars and annihilate to produc...Dark stars; WIMP; Weakly interacting massive particles2009
4 Lupton, John MarkEnergetic disorder limits energy transfer in semiconductor nanocrystal-DNA-dye conjugatesWe demonstrate the influence of spectral linewidths of individual donor-acceptor couples on energy transfer efficiency in semiconductor nanocrystal-DNA-organic dye conjugates. Temperature-dependent single molecule and ensemble spectroscopy data are analyzed using the Förster theory within the mac...2009
5 Vardeny, Zeev Valentine; Nahata, AjayTHz anomalous transmission in plasmonic lattices; incidence angle dependenceThe phenomenon of anomalous transmission through subwavelength aperture arrays in metallic films (plasmonic lattices) is thought to be mediated by surface plasmon polaritons (SPP) on the film surfaces. Using terahertz time-domain spectroscopy we systematically studied the anomalous transmission spec...THz anomalous transmission; Plasmonic lattices; Incidence angle dependence; THz radiation; Light polarization; Effective dielectric response; Notch filter2009
6 DeTar, CarletonB̄→D*ℓν̄ form factor at zero recoil from three-flavor lattice QCD: a model independent determination of [Vcb]We present the first lattice QCD calculation of the form factor for B→ D* lv with three flavors of sea quarks. We use an improved staggered action for the light valence and sea quarks (the MILC configurations), and the Fermilab action for the heavy quarks. The form factor is computed at zero recoi...Staggered quarks2009-01
7 DeTar, CarletonB→πlν semileptonic form factor from three-flavor lattice QCD: a model-independent determination of [Vub]We calculate the form factor f+(q2) for B-meson semileptonic decay in unquenched lattice QCD with 2 + 1 flavors of light sea quarks. We use Asqtad-improved staggered light quarks and a Fermilab bottom quark on gauge configurations generated by the MILC Collaboration. We simulate with several light...Semileptonic decay2009-03
8 Gondolo, PaoloDark matter axions revisitedWe study for what specific values of the theoretical parameters the axion can form the totality of cold dark matter. We examine the allowed axion parameter region in the light of recent data collected by the WMAP5 mission plus baryon acoustic oscillations and supernovae, and assume an inflationary...WMAP5 mission; PQ symmetry; Anharmonicity; Misalignment angle2009-08
9 Gondolo, PaoloDark matter in the MSSM golden regionDark matter is examined within the ‘‘golden region'' of the minimal supersymmetric standard model. This region satisfies experimental constraints, including a lower bound on the Higgs mass of 114 GeV, and minimizes fine-tuning of the Z boson mass. Here we impose additional constraints (particula...MSSM golden region; Neutralinos; Higgs mass2009-02
10 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
11 Boehme, ChristophExperimental discrimination of geminate and non-geminate recombination in a-Si:HA study of charge-carrier recombination in intrinsic hydrogenated amorphous silicon (a-Si:H) is presented using pulsed electrically and pulsed optically detected magnetic-resonance spectroscopies in order to measure the influence of spin-dependent recombination on photoluminescence (PL) and photoc...Geminate recombination2009-05
12 Boehme, ChristophFast nuclear spin hyperpolarization of phosphorus in siliconWe experimentally demonstrate a method for obtaining nuclear spin hyperpolarization, that is, polarization significantly in excess of that expected at thermal equilibrium. By exploiting a nonequilibrium Overhauser process, driven by white light irradiation, we obtain more than 68% negative nuclear p...Hyperpolarization; Spin coherence; Electrical readout2009-01
13 Boehme, ChristophInfluence of disorder on electrically and optically detected electron spin nutationA numerical study of the influence of disorder in semiconductors on spin-Rabi nutation observed with pulsed electrically or optically detected magnetic-resonance techniques (pEDMR and pODMR, respectively ) is presented. It is shown that transient nutation signals of disordered spin ensembles differ ...Electron spin nutations2009-02
14 Lupton, John MarkIntermittency in second-harmonic radiation from plasmonic hot spots on rough silver filmsSurface enhancement of electromagnetic fields in plasmonic hot spots formed on rough silver films enables the observation of second-harmonic generation (SHG) from single metal nanoparticles. Nonlinear light scattering from these particles exhibits blinking in analogy to luminescence from single qu...Harmonic radiation; Plasmonic hot spots; Second harmonic generation; SHG2009-10
15 Sokolsky, PierreMeasurement of the flux of ultra high energy cosmic rays by the stereo techniqueThe High Resolution Fly's Eye (HiRes) experiment has measured the flux of ultrahigh energy cosmic rays using the stereoscopic air fluorescence technique. The HiRes experiment consists of two detectors that observe cosmic ray showers via the fluorescence light they emit. HiRes data can be analyzed i...Ultrahigh energy cosmic rays; Fluorescence; Energy spectrum; GZK cutoff2009-08
16 Mishchenko, EugeneMesoscopic spin-Hall effect in 2D electron systems with smooth boundariesThe spin-Hall effect in a ballistic 2D electron gas with Rashba-type spin-orbit coupling and smooth edge confinement is studied. We predict that the interplay of semiclassical electron motion and quantum dynamics of spins leads to several distinct features in spin density along the edge that origina...Spin- Hall effect; 2D electron systems2009-05
17 Dawson, KyleMulti-wavelength study of XMMU J2235.3-2557: the most massive galaxy cluster at z > 1The galaxy cluster XMMU J2235.3−2557 (hereafter XMM2235), spectroscopically confirmed at z = 1.39, is one of the most distant X-ray selected galaxy clusters. It has been at the center of a multi-wavelength observing campaign with ground and space facilities. Aims. We characterize the galaxy popula...XMMU J2235.3-2557; XMM2235; X-rays; Redshift2009-12
18 Dawson, KyleMultiwavelength observations of a rich galaxy cluster at z ~ 1: the HST/ACS colour-magnitude diagramXMMU J1229+0151 is a rich galaxy cluster with redshift z = 0.975 that was serendipitously detected in X-rays within the scope of the XMM-Newton Distant Cluster Project. Both HST/ACS observations in the i775 and z850 passbands and VLT/FORS2 spectroscopy were obtained, in addition to follow-up Near-In...Passive galaxies; Redshift2009-07
19 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
20 Vardeny, Zeev ValentineOptical probes of ∏-conjugated polymer blends with strong acceptor moleculesWe used a variety of optical probes to study the primary and long-lived photoexcitations in blends of polyphenylene-vinylene derivative poly(2-methoxy-5(2'-ethyl)hexoxy-phenylenevinylene) (MEH-PPV) with various concentrations of a strong electron-acceptor molecule 2,4,7-trinitro-9-fluorenone (TNF...pi-conjugated polymers; pi-conjugated polymer blends; Acceptor molecules; Optical probes; Photoexcitations; MEH-PPV; Electron acceptors; Organic solar cells2009-05
21 Gondolo, PaoloSolar neutrino limit on axions and keV-mass bosonsThe all-flavor solar neutrino flux measured by the Sudbury Neutrino Observatory constrains nonstandard energy losses to less than about 10% of the Sun's photon luminosity, superseding a helioseismological argument and providing new limits on the interaction strength of low-mass particles. For the ...Interaction strength; keV-mass2009-05
22 Vardeny, Zeev Valentine; Nahata, AjayTerahertz spectroscopy of plasmonic fractalsWe use terahertz time-domain spectroscopy to study the transmission properties of metallic films perforated with aperture arrays having deterministic or stochastic fractal morphologies (‘‘plasmonic fractals''), and compare them with random aperture arrays. All of the measured plasmonic fractals...Plasmonic fractals; Random aperture arrays2009-03
23 Vardeny, Zeev ValentineUltrafast dynamics in metallic and semiconducting carbon nanotubesTransient polarized pump/probe transmission changes upon pulse photoexcitation at 1.6 eV were measured in chiral enriched carbon nanotubes ensembles of both metallic and semiconductor characters, in a very broad probe spectral range from mid-IR to visible, combining several ultrafast laser systems...2009-11
24 Lupton, John MarkUnraveling the inhomogeneously broadened absorption spectrum of conjugated polymers by single-molecule light-harvesting action spectroscopyThe distribution of chromophores in single polymer chains is revealed by photoluminescence excitation spectroscopy under excitation of the backbone and detection of emission from an end cap. Spectral broadening in excitation exceeds that in emission. An increase in vibronic coupling for shorter (h...Spectral broadening; Chromophores2009-10
25 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
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