3,128 research outputs found
A visualization of the damage in Lead Tungstate calorimeter crystals after exposure to high-energy hadrons
The anticipated performance of calorimeter crystals in the environment
expected after the planned High-Luminosity upgrade of the Large Hadron Collider
(HL-LHC) at CERN has to be well understood, before informed decisions can be
made on the need for detector upgrades. Throughout the years of running at the
HL-LHC, the detectors will be exposed to considerable fluences of fast hadrons,
that have been shown to cause cumulative transparency losses in Lead Tungstate
scintillating crystals. In this study, we present direct evidence of the main
underlying damage mechanism. Results are shown from a test that yields a direct
insight into the nature of the hadron-specific damage in Lead Tungstate
calorimeter crystals exposed to 24 GeV/c protons.Comment: 8 pages, 6 figure
Kink fluctuation asymptotics and zero modes
In this paper we propose a refinement of the heat kernel/zeta function
treatment of kink quantum fluctuations in scalar field theory, further
analyzing the existence and implications of a zero energy fluctuation mode.
Improved understanding of the interplay between zero modes and the kink heat
kernel expansion delivers asymptotic estimations of one-loop kink mass shifts
with remarkably higher precision than previously obtained by means of the
standard Gilkey-DeWitt heat kernel expansion.Comment: 21 pages, 8 figures, to be published in The European Physical Journal
Advanced content-based semantic scene analysis and information retrieval: the SCHEMA project
The aim of the SCHEMA Network of Excellence is to bring together a critical mass of universities, research centers, industrial partners and end users, in order to design a reference system for content-based semantic scene analysis, interpretation and understanding. Relevant research areas include: content-based multimedia analysis and automatic annotation of semantic multimedia content, combined textual and multimedia information retrieval, semantic -web, MPEG-7 and MPEG-21 standards, user interfaces and human factors. In this paper, recent advances in content-based analysis, indexing and retrieval of digital media within the SCHEMA Network are presented. These advances will be integrated in the SCHEMA module-based, expandable reference system
Femtosecond multichannel photodissociation dynamics of CH3I from the A band by velocity map imaging
4 pages, 3 figures, 1 table.The reaction times of several well-defined channels of the CâI bond rupture of methyl iodide from
the A band, which involves nonadiabatic dynamics yielding ground state I(2P3/2) and spin-orbit
excited I*(2P1/2) and ground and vibrationally excited CH3 fragments, have been measured by a
combination of a femtosecond laser pump-probe scheme and velocity map imaging techniques using
resonant detection of ground state CH3 fragments. The reaction times found for the different
channels studied are directly related with the nonadiabatic nature of this multidimensional
photodissociation reaction.Two of the authors (J. G. I. and J. D.) gratefully acknowledge financial support
from the FPI program and the CSIC-Unidades Asociadas
program, respectively, of the Spanish Ministry of
Education and Science (MEC). This work has been financed
by the Spanish MEC through Grant No. CTQ2005-08493-
C02-01.Peer reviewe
On domain walls in a Ginzburg-Landau non-linear S^2-sigma model
The domain wall solutions of a Ginzburg-Landau non-linear -sigma hybrid
model are unveiled. There are three types of basic topological walls and two
types of degenerate families of composite - one topological, the other
non-topological- walls. The domain wall solutions are identified as the finite
action trajectories (in infinite time) of a related mechanical system that is
Hamilton-Jacobi separable in sphero-conical coordinates. The physical and
mathematical features of these domain walls are thoroughly discussed.Comment: 26 pages, 18 figure
Large deviations principle for the cubic NLS equation
In this paper, we present a probabilistic study of rare phenomena of the cubic nonlinear Schrodinger equation on the torus in a weakly nonlinear setting. This equation has been used as a model to numerically study the formation of rogue waves in deep sea. Our results are twofold: first, we introduce a notion of criticality and prove a Large Deviations Principle (LDP) for the subcritical and critical cases. Second, we study the most likely initial conditions that lead to the formation of a rogue wave, from a theoretical and numerical point of view. Finally, we propose several open questions for future research
Supergeometry of Three Dimensional Black Holes
We show how the supersymmetric properties of three dimensional black holes
can be obtained algebraically. The black hole solutions are constructed as
quotients of the supergroup by a discrete subgroup of its
isometry supergroup. The generators of the action of the isometry supergroup
which commute with these identifications are found. These yield the
supersymmetries for the black hole as found in recent studies as well as the
usual geometric isometries. It is also shown that in the limit of vanishing
cosmological constant, the black hole vacuum becomes a null orbifold, a
solution previously discussed in the context of string theory.Comment: 12 pages, harvmac, discussion of rotating black hole added, some
minor corrections, reference adde
Private concession contracts for toll roads in Spain: analysis and recommendations.
Spain has a long history of using the private sector to help build and operate public infrastructure, particularly roads. This article presents new data about toll motorways. The authors found that contracts in Spain are characterized by significant traffic overestimations and frequent renegotiations, which can lead to toll modifications or longer contracts. They suggest reasons for this and some solutionsâboth of which have significance for other countries
Killing spinors, the adS black hole and I(ISO(2,1)) gravity
We construct a supersymmetric extension of the
Chern-Simons gravity and show that certain particle-like solutions and the adS
black-hole solution of this theory are supersymmetric.Comment: 12 pages, uses phyzz
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