Solar supergranulation revealed by granule tracking

Context: Supergranulation is a pattern of the velocity field at the surface of the Sun, which has been known about for more than fifty years, however, no satisfactory explanation of its origin has been proposed. Aims: New observational constraints are therefore needed to guide theoretical approaches which hesitate between scenarios that either invoke a large-scale instability of the surface turbulent convection or a direct forcing by buoyancy. Method: Using the 14-Mpixel CALAS camera at the Pic-du-Midi observatory, we obtained a 7.5h-long sequence of high resolution images with unprecedented field size. Tracking granules, we have determined the velocity field at the Sun's surface in great detail from a scale of 2.5Mm up to 250Mm. Results: The kinetic energy density spectrum shows that supergranulation peaks at 36Mm and spans on scales ranging between 20Mm and 75Mm. The decrease of supergranular flows in the small scales is close to a $k^{-2}$-power law, steeper than the equipartition Kolmogorov one. The probability distribution function of the divergence field shows the signature of intermittency of the supergranulation and thus its turbulent nature.Comment: 4 pages, accepted in Astronomy and Astrophysics (Letters

Biorefinery Done Right

Following the COP21 conference in Paris, most of the world’s industrialized countries, as well as emerging markets, pledged to reduce or stabilize their greenhouse gas (GHG) emissions in light of increasing concerns regarding climate change [1]. The necessity to decrease GHG emissions will have implications on the consumption patterns of different types of energies around the world. Apart from the obvious need to replace part of the increasing fossil fuel consumption in transportation (including road, rail, air and sea), there is a growing demand in other sectors as well, such as for electricity production, heating and cooling. Many opportunities are being investigated to address some of the issues related to this green energy transition, including the increased harnessing of alternative energy sources such as wind, solar, hydro, geothermal and biomass. Despite varying potential for each of the mentioned energy sources to help replace or supplement fossil fuels, only biomass currently has the potential to address most of these needs without requiring significant changes to existing energy distribution networks. For example, biomass can be burnt to generate combined heat and power, but it can also be used as a source of carbon to produce biofuels. In the latter case, biofuels such as ethanol could be blended into the existing fuel pool as well as distributed and utilized in engines without requiring significant modifications to the existing chain of distribution. This adaptiveness is not necessarily the case when considering electric vehicles (EV), although they are also of crucial importance towards collectively reducing GHG emissions. This manuscript will review the Biorefinery Done Right-concept, developed by the company RéSolve Énergie in close collaboration with the Biomass Technology Laboratory. This simple feedstock-agnostic technology allows conversion of any type of residual biomass (including but not limited to softwood bark) to three-types of biofuels. The first objective is to take advantage of the carbohydrate content in the biomass through hydrolysis of the constitutive hemicellulose and cellulose. The fermentable sugars are then converted to ethanol, achieved without any constraints, since the RéSolve process generates a hydrolysate with very low inhibitor levels. The lignin recovered from the process is essentially unmodified lignin and after washing, it is pelletized. Pellets, containing the most energetic components of the lignocellulosic biomass, can provide up to 26 GJ/tonne. Finally, the non-fermentable sugars (C5), as well as the lignin that does not comply with Grade A lignin characteristics, are predigested for utilization in a classical biomethanation system. Hence, through this approach, 100% of the carbon from the biomass is converted into commercial products, which at this point are all related to the energy market.The authors would like to acknowledge the participation of RéSolve Énergie to this project as well as the CRIBIQ, MITACS and NSERC who contributed in funding this work

Progress on development of the new FDIRC PID detector

International audienceWe present a progress status of a new concept of PID detector called FDIRC, intended to be used at the SuperB experiment, which requires π/K separation up to a few GeV/c. The new photon camera is made of the solid fused-silica optics with a volume 25× smaller and speed increased by a factor of 10 compared to the BaBar DIRC, and therefore will be much less sensitive to electromagnetic and neutron background

Évolution de la contribution française à l'upgrade de LHCb

Ce document décrit l'évolution de la contribution française à l'upgrade de LHCb. Il s'inscrit dans le prolongement de la Lettre d'Intention [1], du Framework TDR [2], du document soumis au Conseil scientifique de l'IN2P3 le 21 juin 2012 [3], et des Technical Design Reports soumis au LHCC en novembre 2013 [4, 5]. Ces derniers concernent le détecteur de vertex et les détecteurs utilisés dans l'identification des particules. La contribution française s'est cristallisée autour de quatre grands projets : l'électronique front-end des calorimètres et du trajectographe à fibres scintillantes, le système de déclenchement de premier niveau et la carte de lecture à 40MHz commune à l'ensemble des sous-systèmes. Dans ce document nous décrivons les contributions envisagées et les ressources nécessaires pour mener à bien ces projets

Contribution française à l'upgrade de LHCb

La contribution française à l'upgrade de LHCb est d etaillée dans ce document et s'inscrit dans le prolongement du Framework TDR soumis au LHCC le 25 mai 2012. La France a contribué à la conception et à la réalisation de la mécanique et de l'électronique de lecture des calorimètres. Elle est l'acteur principal du système de déclenchement de premier niveau et l'initiatrice du projet DIRAC, progiciel de traitement et d'analyse de données dans un environnement distribué. Les physiciens et ingénieurs français ont de nombreuses responsabilités de premier plan et sont très fortement impliqués dans l'analyse des données. Les groupes français souhaitent poursuivre leur forte participation a l'expérience en contribuant a son upgrade, notamment l'électronique de lecture des calorimètres et du trajectographe en fibres scintillantes ainsi qu'au data processing

Contribution française à l'upgrade de LHCb

La contribution française à l'upgrade de LHCb est d etaillée dans ce document et s'inscrit dans le prolongement du Framework TDR soumis au LHCC le 25 mai 2012. La France a contribué à la conception et à la réalisation de la mécanique et de l'électronique de lecture des calorimètres. Elle est l'acteur principal du système de déclenchement de premier niveau et l'initiatrice du projet DIRAC, progiciel de traitement et d'analyse de données dans un environnement distribué. Les physiciens et ingénieurs français ont de nombreuses responsabilités de premier plan et sont très fortement impliqués dans l'analyse des données. Les groupes français souhaitent poursuivre leur forte participation a l'expérience en contribuant a son upgrade, notamment l'électronique de lecture des calorimètres et du trajectographe en fibres scintillantes ainsi qu'au data processing

The DIRC Particle Identification System for the BABAR Experiment

A new type of ring-imaging Cherenkov detector is being used for hadronic particle identification in the BABAR experiment at the SLAC B Factory (PEP-II). This detector is called DIRC, an acronym for Detection of Internally Reflected Cherenkov (Light). This paper will discuss the construction, operation and performance of the BABAR DIRC in detail