Conversion électro-optique du signal et découplage actif d'un capteur IRM endoluminal à liaison optique

International audienceUne boucle endoluminale radiofréquence (RF) située à proximité de la zone à examiner permet d'avoir localement un rapport signal sur bruit élevé qui peut être mis à profit pour augmenter la résolution spatiale des images de RM. Ce type de capteur permet en particulier d'analyser la paroi de l'intestin qui permettrait d'améliorer le bilan d'extension tumorale [1]. Malheureusement, les câbles coaxiaux, couramment utilisés pour transmettre le signal RMN et le courant nécessaire au découplage actif du capteur de réception, peuvent induire des échauffements des tissus compromettant l'utilisation clinique d'un tel capteur. En effet, le champ électrique E z accompagnant le champ magnétique RF B 1 , induit des courants RF le long du câble et augmente ainsi le taux d'absorption spécifique (TAS) local [2]. Afin d'assurer la sécurité du patient, l'utilisation d'une connexion optique est une solution alternative élégante pour supprimer ces risques d'échauffements. La conversion électro-optique (EO) des signaux [3] et le découplage optique [4] sont démontrés sur la base d'un capteur endoluminal

Conversion électro-optique du signal et découplage actif d'un capteur IRM endoluminal à liaison optique

International audienceUne boucle endoluminale radiofréquence (RF) située à proximité de la zone à examiner permet d'avoir localement un rapport signal sur bruit élevé qui peut être mis à profit pour augmenter la résolution spatiale des images de RM. Ce type de capteur permet en particulier d'analyser la paroi de l'intestin qui permettrait d'améliorer le bilan d'extension tumorale [1]. Malheureusement, les câbles coaxiaux, couramment utilisés pour transmettre le signal RMN et le courant nécessaire au découplage actif du capteur de réception, peuvent induire des échauffements des tissus compromettant l'utilisation clinique d'un tel capteur. En effet, le champ électrique E z accompagnant le champ magnétique RF B 1 , induit des courants RF le long du câble et augmente ainsi le taux d'absorption spécifique (TAS) local [2]. Afin d'assurer la sécurité du patient, l'utilisation d'une connexion optique est une solution alternative élégante pour supprimer ces risques d'échauffements. La conversion électro-optique (EO) des signaux [3] et le découplage optique [4] sont démontrés sur la base d'un capteur endoluminal

First results from the OSQAR photon regeneration experiment: No light shining through a wall

A new method to amplify the photon-axion conversions in magnetic field is proposed using a buffer gas at a specific pressure. As a first result, new bounds for mass and coupling constant for purely laboratory experiments aiming to detect any hypothetical scalars and pseudo-scalars which can couple to photons were obtained at 95% confidence level, excluding the PVLAS result newly disclaimed.Comment: 4 pages, 5 figure

Low cost power and flow rates measurements in manufacturing plants

International audienceThe ability to measure, monitor and control energy consumption at several key locations in a manufacturing plant is a major prerequisite for any efficient energy management program. To identify and evaluate energy savings, one must get a clear view of how the energy is used. Furthermore, measuring energy flows is one of the necessary conditions for long lasting energyefficient solutions. Most of the time energy managers are reluctant to put in place power and flow rate measuring devices either because of their cost or because this implies stopping production. To find acceptable and economical solutions for long lasting energy measurements in Industry, EDF R&D launched a 3-year collaborative research project called CHIC. This project is funded by the French National Research Agency (ANR) and involves 7 partners. Its total budget amounts to 2.55 M€. This project serves two purposes: to build a clamp-on power meter that could be installed around multi-conductors power cables without interrupting power supply, and to build power and flow meters that derive the sought-for variable from mathematical models and from simple and easy to collect other physical measurements (e.g. command signals, etc...)

Fostering Energy Efficiency in manufacturing plants through economical breakthroughs in power and flow rate measurement

International audienceThe ability to measure, monitor and control energy consumption at several key locations in a manufacturing plant is a major prerequisite for any efficient energy management program. To identify and evaluate energy savings, one must get a clear view of how the energy is used. Furthermore, measuring energy flows is one of the necessary conditions for long lasting energy-efficient solutions. Most of the time energy managers are reluctant to put in place power and flow rate measuring devices either because of their cost or because this implies disrupting production. To find acceptable and economical solutions for long lasting energy measurements in Industry, EDF R&D launched a 3-year collaborative research project called CHIC. This project is funded by the French National Research Agency (ANR) and involves 7 partners. Its total budget amounts to 2.55 M€. Because energy measuring devices acceptability relies mostly on their ability to be installed without disrupting production as well as on their installation and maintenance costs, two non intrusive and low cost technologies will be explored within the project: A physical approach is being used to build a clamp-on power meter that could be installed around multi-conductors power cables without interrupting power supply, A software based approach is being used to build power and flow meters that derive the sought-for variable from models and from simple and easy to collect other physical measurements (e.g. command signals, etc...). Introductio

First Results of the Full-Scale OSQAR Photon Regeneration Experiment

Recent intensive theoretical and experimental studies shed light on possible new physics beyond the standard model of particle physics, which can be probed with sub-eV energy experiments. In the second run of the OSQAR photon regeneration experiment, which looks for the conversion of photon to axion (or Axion-Like Particle), two spare superconducting dipole magnets of the Large Hadron Collider (LHC) have been used. In this paper we report on first results obtained from a light beam propagating in vacuum within the 9 T field of two LHC dipole magnets. No excess of events above the background was detected and the two-photon couplings of possible new scalar and pseudo-scalar particles could be constrained.Comment: 5 pages, 4 figures, Photon 2011 Conference, Submitted to JO

Axion Search by Laser-based Experiment OSQAR

International audienceLaser-based experimentOSQAR in CERN is aimed to the search of the axions by twomethods. The photon regeneration experiment is using two LHC dipole magnets of the length 14.3 m and magnetic field 9.5 T equipped with an optical barrier at the end of the first magnet. It looks as light shining through the wall. No excess of events above the background was detected at this arrangement. Nevertheless, this result extends the exclusion region for the axion mass. The second method wants to measure the ultra-fine Vacuum Magnetic Birefringence for the first time. An optical scheme with electro-optical modulator has been proposed, validated and subsequently improved. Cotton-Mouton constant for air was determined in this experiment setup

Progress of the Laser-based Experiment OSQAR

International audienceOSQAR experiment at CERN is based on two laser methods for search of axions and scalar particles. The light shining through the wall experiment has been using two LHC dipole magnets with an optical barrier, argon laser, and cooled 2D CCD detector for the measuring of expected regenerated photons. The second method wants to measure the Vacuum Magnetic Birefringence. An optical set-up with electro-optical modulator has been proposed, validated and subsequently improved in collaborating institutes. Cotton-Muton effect in nitrogen was measured by this method. Prototype of a one-meter long laser cavity was developed for this experiment

Towards a fully non invasive probe for SAR assessment in MRI phantom experiments

International audienc