6,727 research outputs found
A new method based on noise counting to monitor the frontend electronics of the LHCb muon detector
A new method has been developed to check the correct behaviour of the
frontend electronics of the LHCb muon detector. This method is based on the
measurement of the electronic noise rate at different thresholds of the
frontend discriminator. The method was used to choose the optimal discriminator
thresholds. A procedure based on this method was implemented in the detector
control system and allowed the detection of a small percentage of frontend
channels which had deteriorated. A Monte Carlo simulation has been performed to
check the validity of the method
Predicting the critical density of topological defects in O(N) scalar field theories
O(N) symmetric field theories describe many critical
phenomena in the laboratory and in the early Universe. Given N and ,
the dimension of space, these models exhibit topological defect classical
solutions that in some cases fully determine their critical behavior. For N=2,
D=3 it has been observed that the defect density is seemingly a universal
quantity at T_c. We prove this conjecture and show how to predict its value
based on the universal critical exponents of the field theory. Analogously, for
general N and D we predict the universal critical densities of domain walls and
monopoles, for which no detailed thermodynamic study exists. This procedure can
also be inverted, producing an algorithm for generating typical defect networks
at criticality, in contrast to the canonical procedure, which applies only in
the unphysical limit of infinite temperature.Comment: 4 pages, 3 figures, uses RevTex, typos in Eq.(11) and (14) correcte
Desempenho produtivo de genótipos de cana-de-açúcar (Saccharum spp.) na região noroeste do Rio Grande do Sul, safra 2012/13.
The formation of vortex loops (strings) in continuous phase transitions
The formation of vortex loops (global cosmic strings) in an O(2) linear sigma
model in three spatial dimensions is analyzed numerically. For over-damped
Langevin dynamics we find that defect production is suppressed by an
interaction between correlated domains that reduces the effective spatial
variation of the phase of the order field. The degree of suppression is
sensitive to the quench rate. A detailed description of the numerical methods
used to analyze the model is also reported.Comment: LaTeX, 17 pages, 6 eps figures 2 references and a footnote adde
Avaliação da emergência e do rendimento de colmos em genótipos de cana-de-açúcar em Pelotas, RS.
Defect formation and local gauge invariance
We propose a new mechanism for formation of topological defects in a U(1)
model with a local gauge symmetry. This mechanism leads to definite
predictions, which are qualitatively different from those of the Kibble-Zurek
mechanism of global theories. We confirm these predictions in numerical
simulations, and they can also be tested in superconductor experiments. We
believe that the mechanism generalizes to more complicated theories.Comment: REVTeX, 4 pages, 2 figures. The explicit form of the Hamiltonian and
the equations of motion added. To appear in PRL (http://prl.aps.org/
Testing the Kibble-Zurek Scenario with Annular Josephson Tunnel Junctions
In parallel with Kibble's description of the onset of phase transitions in
the early universe, Zurek has provided a simple picture for the onset of phase
transitions in condensed matter systems, strongly supported by agreement with
experiments in He3. In this letter we show how experiments with annular
Josephson tunnel Junctions can and do provide further support for this
scenario.Comment: Revised version with correct formula for the Swihart velocity. The
results are qualitatively the same as with the previous version but differ
quantitatively. 4 pages, RevTe
Avaliação de genĂłtipos de cana-de-açúcar (Saccharum spp.) em salto do JacuĂ/RS, safras 2010/11 e 2011/12.
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