1,407 research outputs found
Modification of Ni - nanotubes by implanting ions C3+
Using PET track-etched membranes with thickness of 12 μm as template, polycrystalline nickel nanotubes with outer diameter of 380 nm and wall thickness 95 nm were synthesized by electrochemical method. A comprehensive study of the structural, morphological and electrical characteristics of irradiated at different conditions Ni nanotubes was carried out. The ability of modification of structural parameters such as lattice parameters and the average size of crystallites and conductivity of Ni nanotubes by irradiated with С3+ ions with energy 1.75 MeV/nucleon and fluence ranging from 1 × 109 to 5 × 1011 cm-2 was shown
Time-resolved broadband analysis of slow-light propagation and superluminal transmission of electromagnetic waves in three-dimensional photonic crystals
A time-resolved analysis of the amplitude and phase of THz pulses propagating through three-dimensional photonic crystals is presented. Single-cycle pulses of THz radiation allow measurements over a wide frequency range, spanning more than an octave below, at and above the bandgap of strongly dispersive photonic crystals. Transmission data provide evidence for slow group velocities at the photonic band edges and for superluminal transmission at frequencies in the gap. Our experimental results are in good agreement with finite-difference-time-domain simulations
Left-Handed W Bosons at the LHC
The production of W bosons in association with jets is an important
background to new physics at the LHC. Events in which the W carries large
transverse momentum and decays leptonically lead to large missing energy and
are of particular importance. We show that the left-handed nature of the W
coupling, combined with valence quark domination at a pp machine, leads to a
large left-handed polarization for both W^+ and W^- bosons at large transverse
momenta. The polarization fractions are very stable with respect to QCD
corrections. The leptonic decay of the W bosons translates the common
left-handed polarization into a strong asymmetry in transverse momentum
distributions between positrons and electrons, and between neutrinos and
anti-neutrinos (missing transverse energy). Such asymmetries may provide an
effective experimental handle on separating W + jets from top quark production,
which exhibits very little asymmetry due to C invariance, and from various
types of new physics.Comment: 32 pages, revtex, 17 figures, 3 tables, v2 minor corrections to ME+PS
results, no changes to conclusions, added reference
Next-to-leading order diphoton+2-jet production at the LHC
We present results from a recent calculation of prompt photon-pair production
in association with two jets to next-to-leading order (NLO) at the LHC. The
virtual contribution is evaluated using the BlackHat library, a numerical
implementation of on-shell methods for one-loop amplitudes, in conjunction with
SHERPA. We study four sets of cuts: standard jet cuts, a set of Higgs-related
cuts suggested by ATLAS, and corresponding sets which isolate the kinematic
region where the process becomes the largest background to Higgs production via
vector-boson fusion.Comment: 10 pages, 4 figures, Presented at 11th International Symposium on
Radiative Corrections (RADCOR 2013), 22-27 September 2013, Lumley Castle
Hotel, Durham, U
Time-resolved broadband analysis of slow-light propagation and superluminal transmission of electromagnetic waves in three-dimensional photonic crystals
A time-resolved analysis of the amplitude and phase of THz pulses propagating
through three-dimensional photonic crystals is presented. Single-cycle pulses
of THz radiation allow measurements over a wide frequency range, spanning more
than an octave below, at and above the bandgap of strongly dispersive photonic
crystals. Transmission data provide evidence for slow group velocities at the
photonic band edges and for superluminal transmission at frequencies in the
gap. Our experimental results are in good agreement with
finite-difference-time-domain simulations.Comment: 7 pages, 11 figure
Next-to-Leading Order W + 5-Jet Production at the LHC
We present next-to-leading order QCD predictions for the total cross section
and for a comprehensive set of transverse-momentum distributions in W + 5-jet
production at the Large Hadron Collider. We neglect the small contributions
from subleading-color virtual terms, top quarks and some terms containing four
quark pairs. We also present ratios of total cross sections, and use them to
obtain an extrapolation formula to an even larger number of jets. We include
the decay of the boson into leptons. This is the first such computation
with six final-state vector bosons or jets. We use BlackHat together with
SHERPA to carry out the computation.Comment: RevTex, 27 pages, 7 figures, v2 minor corrections and corrected
reference
Analysis of a semi-empirical leading-edge slat noise prediction model
In this paper semi-empirical formulas are presented that relate macroscopic flow parameters observed in the slat cove and semi-empirical constants proposed in Guo’s semianalytical model. Fourteen slat configurations were simulatedusing the Lattice Boltzmann Method (LBM) implemented in PowerFLOWR commercial software. These results show an elementary relation between the four semiempirical constants proposed in Guo’s slat model and importantflow parameters, e.g., the shear-layer path length and the maximum shear velocity. Consequently, those four semi-empirical constants were rewritten in terms of two empirical constants which values can be derived fromRANS simulations. The proposed noise prediction model is consequently validated against wind tunnel aeroacoustics tests performed with the 30P30N high-lift device model. Experiments performed in the UTwente AeroacousticWind Tunnel at Rec = 1 x 106 and M = 0.15 showed good overall agreement between noise measurements and the proposed slat noise prediction model
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