7,346 research outputs found
Imaging of Thermal Domains in ultrathin NbN films for Hot Electron Bolometers
We present low-temperature scanning electron microscopy (LTSEM)
investigations of superconducting microbridges made from ultrathin NbN films as
used for hot electron bolometers. LTSEM probes the thermal structure within the
microbridges under various dc current bias conditions, either via
electron-beam-induced generation of an unstable hotspot, or via the
beam-induced growth of a stable hotspot. Such measurements reveal
inhomogeneities on a micron scale, which may be due to spatial variations in
the NbN film or film-interface properties. Comparison with model calculations
for the stable hotspot regime confirm the basic features of common hot spot
models.Comment: 3 pages, 3 figure
Hadronic Freeze-Out in A+A Collisions meets the Lattice QCD Parton-Hadron Transition Line
We analyze hadrochemical freeze-out in central Pb+Pb collisions at CERN SPS
and LHC energies. Employing the UrQMD hybrid transport model we study the
effects of the final hadron/resonance expansion phase on the hadron
multiplicities established at hadronization. The bulk meson yields freeze out
directly at hadronization whereas the baryon-antibaryon sector is subject to
significant alterations, due to annihilation and regeneration processes. We
quantify the latter changes by survival factors for each species which are
applied to modify the statistical model predictions for the data. The modified
SM analysis recovers the hadronization points, which coincide with the recent
lattice QCD predictions of the parton-hadron transition line at finite
baryochemical potential.Comment: Proceedings of the 8th International Workshop on Critical Point and
Onset of Deconfinement, March 11 to 15, 2013 Napa, California, US
Validity of the Hadronic Freeze-Out Curve
We analyze hadro-chemical freeze-out in central Pb+Pb collisions at CERN SPS
energies, employing the hybrid version of UrQMD which models hadronization by
the Cooper-Frye mechanism, and matches to a final hadron-resonance cascade. We
fit the results both before and after the cascade stage using the Statistical
Hadronization Model, to assess the effect of the cascade phase. We observe a
strong effect on antibaryon yields except anti-{\Omega}, resulting in a shift
in T and {\mu}_B. We discuss the implications for the freeze-out curve.Comment: 5 pages, 8 figures. To appear in the proceedings of Quark Matter
2011, the XXII International Conference on Ultrarelativistic Nucleus-Nucleus
Collision
Prograde garnet growth along complex P-T-t paths: results from numerical experiments on polyphase garnet from the Wölz Complex (Austroalpine basement)
Garnet in metapelites from the Wölz Complex of the Austroalpine crystalline basement east of the Tauern Window characteristically consists of two growth phases, which preserve a comprehensive record of the geothermal history during polymetamorphism. From numerical modelling of garnet formation, detailed information on the pressure-temperature-time (P-T-t) evolution during prograde metamorphism is obtained. In that respect, the combined influences of chemical fractionation associated with garnet growth, modification of the original growth zoning through intragranular diffusion and the nucleation history on the chemical zoning of garnet as P and T change during growth are considered. The concentric chemical zoning observed in garnet and the homogenous rock matrix, which is devoid of chemical segregation, render the simulation of garnet growth through successive equilibrium states reliable. Whereas the first growth phase of garnet was formed at isobaric conditions of ∼3.8kbar at low heating/cooling rates, the second growth phase grew along a Barrovian P-T path marked with a thermal peak of ∼625°C at ∼10kbar and a maximum in P of ∼10.4kbar at ∼610°C. For the heating rate during the growth of the second phase of garnet, average rates faster than 50°CMa−1 are obtained. From geochronological investigations the first growth phase of garnet from the Wölz Complex pertains to the Permian metamorphic event. The second growth phase grew in the course of Eo-Alpine metamorphism during the Cretaceou
Do columnar defects produce bulk pinning?
From magneto-optical imaging performed on heavy-ion irradiated YBaCuO single
crystals, it is found that at fields and temperatures where strong single
vortex pinning by individual irradiation-induced amorphous columnar defects is
to be expected, vortex motion is limited by the nucleation of vortex kinks at
the specimen surface rather than by half-loop nucleation in the bulk. In the
material bulk, vortex motion occurs through (easy) kink sliding. Depinning in
the bulk determines the screening current only at fields comparable to or
larger than the matching field, at which the majority of moving vortices is not
trapped by an ion track.Comment: 5 pages, 5 figures, submitted to Physical Review Letter
High-Fidelity Readout in Circuit Quantum Electrodynamics Using the Jaynes-Cummings Nonlinearity
We demonstrate a qubit readout scheme that exploits the Jaynes-Cummings
nonlinearity of a superconducting cavity coupled to transmon qubits. We find
that in the strongly-driven dispersive regime of this system, there is the
unexpected onset of a high-transmission "bright" state at a critical power
which depends sensitively on the initial qubit state. A simple and robust
measurement protocol exploiting this effect achieves a single-shot fidelity of
87% using a conventional sample design and experimental setup, and at least 61%
fidelity to joint correlations of three qubits.Comment: 5 pages, 4 figure
Transformation of dynamical fluctuation into coherent energy
Studies of noise-induced motions are showing that coherent energy can be
extracted from some kinds of noise in a periodic ratchet.
Recently, energetics of Langevin dynamics is formulated by Sekimoto
[J.Phys.Soc.Jpn, 66 1234 (1997)], which can be applied to ratchet systems
described by Fokker-Planck equation. In this paper, we derive an energetics of
ratchet systems that can be applied to dynamical-noise-induced motion in a
static potential. Analytical efficiency of the energy transformation is derived
for the dynamical noise in an overdumping limit of the system.
Comparison between analytical and numerical studies is performed for chaotic
noise.Comment: 3 pages, 2 figures; submitted to Phys. Rev. Let
Public Channel Cryptography: Chaos Synchronization and Hilbert's Tenth Problem
The synchronization process of two mutually delayed coupled deterministic
chaotic maps is demonstrated both analytically and numerically. The
synchronization is preserved when the mutually transmitted signal is concealed
by two commutative private filters that are placed on each end of the
communication channel. We demonstrate that when the transmitted signal is a
convolution of the truncated time delayed output signals or some powers of the
delayed output signals synchronization is still maintained. The task of a
passive attacker is mapped onto Hilbert's tenth problem, solving a set of
nonlinear Diophantine equations, which was proven to be in the class of
NP-Complete problems. This bridge between two different disciplines,
synchronization in nonlinear dynamical processes and the realm of the NPC
problems, opens a horizon for a new type of secure public-channel protocols
Calibrattions of Cold-Formed Steel Welded Connections
The purpose of this project was to recalibrate the welded connection equations currently contained in the American Iron and Steel Institute (AISI) Specification for the Design of Cold Formed Steel Structural Members (AISI 1996a). Only one factor of safety of 2.50 is presented for the each of the various types of welded connections when using allowable stress design (ASD), but different respective resistance factors are given for load and resistance factor design (LRFD). The data used was solely taken from the research conducted by Pekoz and McGuire (Pekoz and McGuire 1979). Calibrations were carried out and based on both the AISI Specification (AISI 1996a) and the Canadian Sl36 Standard (CSA 1994). The results of this study have already been adopted by both of these cold formed steel design agencies, as well as by the North American Specification for the Design of Cold-Formed Steel Structural Members (NAS 2001)
- …