36,554 research outputs found
First Tests of Gaseous Detectors Made of a Resistive Mesh
We describe here various detectors designs: GEM type, MICROMEGAStype,
PPACtype as well as cascaded detectors made of a resistive mesh manufactured
from a resistive Kapton foil, (20 microns thick, resistivity a few MOhm per
square) by a laser drilling technique. As in any other micropattern detectors
the maximum achievable gas gain of these detectors is restricted by the Raether
limit, however, the resistive mesh makes them and the front end electronics
fully spark protected. This approach could be an alternative or complimentary
to the ongoing efforts in developing MICROMEGAS and GEMs with resistive anode
readout plates and can be especially beneficial in the case of micropattern
detectors combined with a micropixel-type integrated front end electronic
An improved design of spark-protected microstrip gas counters (R-MSGC)
We have developed microstrip gas counters manufactured on standard printed
circuit board and having the following features: resistive cathode strips, thin
(10 micron) metallic anode strips and electrodes protected against surface
discharges by a Coverlay layer at their edges. These features allow the
detector to operate at gas gains as high as can be achieve with the best
microstrip gas counters manufactured on glass substrates. We believe that after
further developments this type of detectors can compete in some applications
with other micropattern detectors, for example MICROMEGAS.Comment: Presented at the 7th RD51 Collaboration meeting, CERN, April 201
Nematic liquid crystal dynamics under applied electric fields
In this paper we investigate the dynamics of liquid crystal textures in a
two-dimensional nematic under applied electric fields, using numerical
simulations performed using a publicly available LIquid CRystal Algorithm
(LICRA) developed by the authors. We consider both positive and negative
dielectric anisotropies and two different possibilities for the orientation of
the electric field (parallel and perpendicular to the two-dimensional lattice).
We determine the effect of an applied electric field pulse on the evolution of
the characteristic length scale and other properties of the liquid crystal
texture network. In particular, we show that different types of defects are
produced after the electric field is switched on, depending on the orientation
of the electric field and the sign of the dielectric anisotropy.Comment: 7 pages, 12 figure
Demonstration of new possibilities of multilayer technology on resistive microstrip/ microdot detectors
The first successful attempts to optimize the electric field in Resistive
Microstrip Gas Chamber and resistive microdot detectors using additional field
shaping strips located inside the detector substrate are describedComment: Presented at the RD-51 mmini week, CERN, June 201
InfluĂȘncia da Ă©poca de plantio, da irrigação suplementar e tratos culturais sobre o rendimento do feijoeiro.
Resumo 177
Suppression of Anderson localization of light and Brewster anomalies in disordered superlattices containing a dispersive metamaterial
Light propagation through 1D disordered structures composed of alternating
layers, with random thicknesses, of air and a dispersive metamaterial is
theoretically investigated. Both normal and oblique incidences are considered.
By means of numerical simulations and an analytical theory, we have established
that Anderson localization of light may be suppressed: (i) in the long
wavelength limit, for a finite angle of incidence which depends on the
parameters of the dispersive metamaterial; (ii) for isolated frequencies and
for specific angles of incidence, corresponding to Brewster anomalies in both
positive- and negative-refraction regimes of the dispersive metamaterial. These
results suggest that Anderson localization of light could be explored to
control and tune light propagation in disordered metamaterials.Comment: 4 two-column pages, 3 figure
- âŠ