268 research outputs found
Advances in the Development of Micropattern Gaseous Detectors with Resistive Electrodes
We describe the most recent efforts made by various groups in implementing
resistive electrodes in micropattern gaseous detectors with the aim to combine
in the same design the best features of RPCs (for the example, their robustness
and spark protection property) with the high granularity and thus the good
position resolution offered by microelectronic technology. In the stream of
this activity, we have recently developed two novel detectors with resistive
electrodes: one was based on resistive micromeshes and the second one is a MSGC
with resistive electrodes. We have demonstrated that the resistive meshes are a
convenient construction element for various designs of spark protective
detectors: RPCs type, GEM type and MICROMEGAS type. These new detectors enable
to considerably enhance the RPC and micropattern detectors applications since
they feature not only a high position resolution but also a relatively good
energy resolution (25-30 persent FWHM at 6 keV) and, if necessary, they can
operate in cascaded mode allowing the achievement of a high overall gas gain.
The main conclusion from these studies is that the implementation of resistive
electrodes in micropattern detectors makes them fully spark protected; on this
basis we consider this direction very promising
Structure de verres de silicophosphate dopés europium : analyse par spectroscopie optique et simulation de dynamique moléculaire
National audienc
Enhancing Magnetic Light Emission with All-Dielectric Optical Nanoantennas
Electric and magnetic optical fields carry the same amount of energy. Nevertheless, the efficiency with which matter interacts with electric optical fields is commonly accepted to be at least 4 orders of magnitude higher than with magnetic optical fields. Here, we experimentally demonstrate that properly designed photonic nanoantennas can selectively manipulate the magnetic versus electric emission of luminescent nanocrystals. In particular, we show selective enhancement of magnetic emission from trivalent europium-doped nanoparticles in the vicinity of a nanoantenna tailored to exhibit a magnetic resonance. Specifically, by controlling the spatial coupling between emitters and an individual nanoresonator located at the edge of a near field optical scanning tip, we record with nanoscale precision local distributions of both magnetic and electric radiative local densities of states (LDOS). The map of the radiative LDOS reveals the modification of both the magnetic and electric quantum environments induced by the presence of the nanoantenna. This manipulation and enhancement of magnetic light-matter interaction by means of nanoantennas opens up new possibilities for the research fields of opto-electronics, chiral optics, nonlinear&nano-optics, spintronics and metamaterials, amongst others.Peer ReviewedPostprint (author's final draft
Europium site symmetry in sol gel silicophosphate glass : FLN spectroscopy and Molecular Dynamics simulation
International audienc
Advanced Photodetectors for Hyperspectroscopy and Other Applications
Hyperspectroscopy is a new method of surface image taking, providing
simultaneously high position and spectral resolutions which allow one to make
some conclusions about chemical compositions of the surfaces. We are now
studying applications of the hyperspctroscopic technique to be used for
medicine. This may allow one to develop early diagnostics of some illnesses, as
for example, skin cancer. For image taking advanced MCPs are currently used,
sensitive in the spectral interval of 450-850 nm. One of the aims of this work
is to extend the hyperspectrocpic method to the UV region of spectra: 185-280
nm. For this we have developed and successfully tested innovative 1D and 2D UV
sealed photosensitive gaseous detectors with resistive electrodes. These
detectors are superior MCPs due to the very low rate of noise pulses and thus
due to the high signal to noise ratio. Other important features of these
detectors are that they have excellent position resolutions - 30 micron in
digital form, are vibration stable and are spark protected. The first results
from the application of these detectors for spectroscopy, hyperspectroscopy and
the flame detection are presented.Comment: Presented at the IEEE Nuclear Science Syposium, Puerto Rico, October
200
The first applications of novel gaseous detectors for UV visualization
We have demonstrated experimentally that recently developed gaseous detectors combined with solid or gaseous photo-cathodes have exceptionally low noise and high quantum efficiency for UV photons while being solar blind. For this reason they can be used for the detection of weak UV sources in daylight conditions. These detectors are extremely robust, can operate in poor gas conditions and are cheap. We present the first results of their applications to hyper-spectroscopy and flame detection in daylight conditions
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