SEPServer is a three-year collaborative project funded by the seventh framework programme (FP7-SPACE) of the European Union. The objective of the project is to provide access to state-of-the-art observations and analysis tools for the scientific community on solar energetic particle (SEP) events and related electromagnetic (EM) emissions. The project will eventually lead to better understanding of the particle acceleration and transport processes at the Sun and in the inner heliosphere. These processes lead to SEP events that form one of the key elements of space weather. In this paper we present the first results from the systematic analysis work performed on the following datasets: SOHO/ERNE, SOHO/EPHIN, ACE/EPAM, Wind/WAVES and GOES X-rays. A catalogue of SEP events at 1 AU, with complete coverage over solar cycle 23, based on high-energy (~68-MeV) protons from SOHO/ERNE and electron recordings of the events by SOHO/EPHIN and ACE/EPAM are presented. A total of 115 energetic particle events have been identified and analysed using velocity dispersion analysis (VDA) for protons and time-shifting analysis (TSA) for electrons and protons in order to infer the SEP release times at the Sun. EM observations during the times of the SEP event onset have been gathered and compared to the release time estimates of particles. Data from those events that occurred during the European day-time, i.e., those that also have observations from ground-based observatories included in SEPServer, are listed and a preliminary analysis of their associations is presented. We find that VDA results for protons can be a useful tool for the analysis of proton release times, but if the derived proton path length is out of a range of 1 AU < s[3 AU, the result of the analysis may be compromised, as indicated by the anti-correlation of the derived path length and release time delay from the asso ciated X-ray flare. The average path length derived from VDA is about 1.9 times the nominal length of the spiral magnetic field line. This implies that the path length of first-arriving MeV to deka-MeV protons is affected by interplanetary scattering. TSA of near-relativistic electrons results in a release time that shows significant scatter with respect to the EM emissions but with a trend of being delayed more with increasing distance between the flare and the nominal footpoint of the Earth-connected field line.
High pressure xenon Time Projection Chambers (TPC) based on secondary scintillation (electroluminescence) signal amplification are being proposed for rare event detection such as directional dark matter, double electron capture and double beta decay detection. The discrimination of the rare event through the topological signature of primary ionisation trails is a major asset for this type of TPC when compared to single liquid or double-phase TPCs, limited mainly by the high electron diffusion in pure xenon. Helium admixtures with xenon can be an attractive solution to reduce the electron diffu- sion significantly, improving the discrimination efficiency of these optical TPCs. We have measured the electroluminescence (EL) yield of Xe–He mixtures, in the range of 0 to 30% He and demonstrated the small impact on the EL yield of the addition of helium to pure xenon. For a typical reduced electric field of 2.5 kV/cm/bar in the EL region, the EL yield is lowered by ∼ 2%, 3%, 6% and 10% for 10%, 15%, 20% and 30% of helium concentration, respectively. This decrease is less than what has been obtained from the most recent simulation framework in the literature. The impact of the addition of helium on EL statistical fluctuations is negligible, within the experimental uncertainties. The present results are an important benchmark for the simulation tools to be applied to future optical TPCs based on Xe-He mixtures ; The NEXT Collaboration acknowledges support from the following agencies and institutions: the European Research Council (ERC) under the Advanced Grant 339787- NEXT; the European Union's Framework Programme for Research and Innovation Horizon 2020 (2014-2020) under the Marie Sklodowska-Curie Grant Agreements No. 674896, 690575 and 740055; the Ministerio de Econom´ıa y Competitividad of Spain under grants FIS2014- 53371-C04, RTI2018-095979, the Severo Ochoa Program SEV-2014-0398 and the Mar´ıa de Maetzu Program MDM-2016-0692; the GVA of Spain under grants PROMETEO/2016/120 and SEJI/2017/011; the Portuguese FCT ...
Convolutional neural networks (CNNs) are widely used state-of-the-art computer vision tools that are becoming increasingly popular in high-energy physics. In this paper, we attempt to understand the potential of CNNs for event classification in the NEXT experiment, which will search for neutrinoless double-beta decay in 136Xe. To do so, we demonstrate the usage of CNNs for the identification of electron-positron pair production events, which exhibit a topology similar to that of a neutrinoless double-beta decay event. These events were produced in the NEXT-White high-pressure xenon TPC using 2.6 MeV gamma rays from a 228Th calibration source. We train a network on Monte Carlo-simulated events and show that, by applying on-the-fly data augmentation, the network can be made robust against differences between simulation and data. The use of CNNs offers significant improvement in signal efficiency and background rejection when compared to previous non-CNN-based analyses ; This study used computing resources from Artemisa, co-funded by the European Union through the 2014-2020 FEDER Operative Programme of the Comunitat Valenciana, project DIFEDER/2018/048. This research used resources of the Argonne Leadership Computing Facility, which is a DOE Office of Science User Facility supported under Contract DE-AC02-06CH11357. The NEXT collaboration acknowledges support from the following agencies and institutions: Xunta de Galicia (Centro singularde investigación de Galicia accreditation 2019-2022), by European Union ERDF, and by the "María de Maeztu" Units of Excellence program MDM-2016-0692 and the Spanish Research State Agency"; the European Research Council (ERC) under the Advanced Grant 339787-NEXT; the European Union's Framework Programme for Research and Innovation Horizon 2020 (2014-2020) under the Grant Agreements No. 674896, 690575 and 740055; the Ministerio de Economía y Competitividad and the Ministerio de Ciencia, Innovación y Universidades of Spain under grants FIS2014-53371-C04, RTI2018-095979, the Severo ...
The X and Y particles predicted in part I have presumably masses of about 2150 and 2900 e. m. respectively. They may decay respectively into a nucleon and a Ξ-yperon by emitting a pion ; lifetimes of the order of 10-10 s. may be expected (weak interactions). The mass of the D-meson is about 1670 e. m. and it decays into a K-meson and one or two pions. Leptonic modes of decay are also possible. The dimension 3 of the charge-space introduced in a preceding paper [2], is confirmed. The correlations considered in that paper are re-examined.
The possible existence of undiscovered elementary particles is discussed. The electric charge Q and the « neutrinonic charge » R, introduced in a preceding paper (x), are given for two such particles, which are baryons : Q = 1, R = 0 and Q = -1, R = -2 ; for the newly discovered D-meson, they are Q = 1, R = 1.
National audience ; Apart from its impact on human health, particulate matter is involved in different environmental problems, such as climate change, tropospheric ozone formation, visibility impairment and hydrology disruption. The role of particulate matter in global warming depends on the composition of the particles, and can lead to a cooling or a warming effect. New scientific results are currently showing the possibility of a stronger warming of the atmosphere by black carbon aerosols than previously thought. For that reason, some scientists claim that strategies to fight global warming should include black carbon emission reductions. These reductions would have an immediate action of slowing global warming, that would complete actions taken on CO2 targeting long-term effects. Such a strategy would bring ancillary benefits in terms of air quality and health effects. At least, past and current European policies of emission reduction of SO2 and NH3 are expected to lead to a decrease in the cooling effect of sulphate and nitrate aerosols, that should be offset as much as possible by efforts on black carbon emission reductions, otherwise the net effect of aerosols on global warming in Europe could go the wrong way. Pollution by particulate matter and tropospheric ozone formation are closely interconnected (particulate matter impacts on photolysis rates, secondary aerosol and ozone have common precursor gases,.), and for that reason the North-American Strategy on Tropospheric Ozone (NARSTO) chose to integrate both aspects in its strategy. Such a concern for consistency should be considered at a higher degree within the Convention on Long Range Transboundary Air Pollution in Europe. Another environmental effect of particulate matter is visibility impairment, mainly attributable to sulphate and organic aerosols. In the United States, it is considered as an important problem that affects not only National Parks but also the entire population. It has been evaluated in the US that monetarised benefits from the Clean Air Act are twice as high as benefits expected from reduced damages to crops by tropospheric ozone. There is very few knowledge about public perception of this environmental problem in Europe, nor European countries seem to have policies to address the issue. However, a recent study found that visibility impairment was more pronounced for most parts of Europe than in the USA. Finally, considering all environmental effects of particulate matter, it is likely that the best way to address such a variety of problems is to search for a simultaneous and general reduction of all air pollutants emissions. It is especially important that future emissions reduction of atmospheric pollutants address black carbon, if we want to avoid the risk that these reductions might lead to counter-productive effects in terms of climate change. ; En dehors de leur effet sur la santé humaine, les particules interviennent dans de nombreuses problématiques environnementales, dont le changement climatique, la formation d'ozone troposphérique, la réduction de la visibilité, et les régimes hydrologiques. L'effet des particules en termes de changement climatique est complexe et emprunte plusieurs voies. Il se traduit par des effets opposés de réchauffement ou de refroidissement de l'atmosphère, notamment selon la composition chimique des particules. On semble assister actuellement à la remise en cause de l'idée qui prévalait que, globalement, les aérosols refroidissaient l'atmosphère, notamment en raison de nouveaux faits scientifiques concernant l'action réchauffante des particules de carbone. Par conséquent, certains scientifiques estiment que les stratégies de lutte contre le changement climatique pourraient inclure une réduction des aérosols de carbone-suie, en permettant un effet à court terme de ralentissement du changement climatique, complémentaire des actions sur le CO2, qui sont plus difficiles à mettre en place à court terme, et qui n'auront pas un impact rapide. Des bénéfices supplémentaires en termes de qualité de l'air sont en outre à attendre d'une telle stratégie. Enfin, les politiques passées et actuelles de réduction importante des émissions de SO2 et NH3 en Europe vont amener une baisse des aérosols secondaires de sulfate et de nitrate, globalement refroidissants, qui devrait être accompagnée par une baisse suffisante des aérosols de carbone-suie, sous peine d'une évolution négative du forçage radiatif global par les aérosols en Europe. Des liens étroits unissent pollution particulaire et formation d'ozone (impact des particules sur les réactions photo-oxydantes, précurseurs communs pour les particules secondaires et l'ozone,.), ce qui a conduit à intégrer complètement les deux stratégies, dans le cadre de la Stratégie Nord Américaine pour l'Ozone Troposphérique (NARSTO). Ce souci de cohérence des stratégies de réduction des particules avec les problèmes de formation d'ozone serait utile à considérer pour la Convention de Genève sur la Pollution Atmosphérique Transfrontière en Europe. Un autre impact qui leur est imputable est la réduction de la visibilité,qui est principalement le fait des aérosols de sulfates et des aérosols organiques. Aux Etats-Unis, il s'agit d'un problème important, considéré comme portant atteinte aux parcs nationaux, mais également à l'ensemble de la population. On a pu évaluer aux USA que les bénéfices monétarisés du Clean Air Act sont deux fois plus importants en termes d'amélioration de la visibilité, que pour la réduction des dommages aux cultures par l'ozone troposphérique. Peu de connaissance est disponible sur la perception de cette question par les populations, et aucun pays d'Europe ne semble disposer d'une politique en la matière. Cependant, une étude récente a estimé que la réduction de visibilité est significativement plus grande en Europe qu'aux Etats-Unis. Au vu de cette synthèse des effets environnementaux des particules, il semble probable que la seule façon d'obtenir des politiques globalement positives pour l'ensemble des effets pris en considération, soit de rechercher une baisse continue et simultanée des émissions de l'ensemble des polluants atmosphériques. Il semble notamment important de veiller à ce que les mesures de réduction des émissions de polluants atmosphériques prises dans le futur, hors gaz à effets de serre, prennent en compte le carbone-suie, car sinon il existe un risque qu'elles conduisent à un effet contre-productif en termes de lutte contre le réchauffement global.
At the beginning of the twentieth century it would be unthinkable, among European scientists, to separate natural science and philosophy. Physicists-philosophers were scientists such as Einstein, Bohr, Heisenberg, Schrödinger, among others, who refounded physics by laying the foundations of quantum mechanics and special and general relativity. In this paper we briefly review how some of these thinkers have looked at the issues of the value of science, the relationship between science and philosophy, and the importance of Greek philosophy to nuclear physics and quantum theory.
Abstract Juxtaposing Beauvoir's view of sexual difference in The Second Sex with Michel Houellebecq's representation of a flailing masculine hegemony in Les Particules élémentaires (Atomised/The Elementary Particles) elucidates how the novel's main protagonists, Bruno and Michel, fall from transcendence to immanence as they navigate new performances of masculinity that are not anchored in traditional virile models. This article examines how this degradation of self occurs and how it can be read through the actions of the main protagonists of Atomised.
Resumen tomado de la publicación ; El objetivo de este trabajo es presentar las bases praxiológicas de un proyecto evaluativo para la Educación Física Escolar, el cual, esta siendo discutido (en el año de la publicación) e implantado gradualmente en las redes municipales, estatales y federales de la enseñanza escolar de Brasil (primer grado). Su finalidad es contribuir, con la formación participativa del alumno a partir de la vehiculación y utilización crítica del conocimiento de la cultura corporal humana. En Brasil, el proceso hegemónico de formación de los profesores y la actividad evaluativa del desempeño escolar, se limitó durante mucho tiempo a verificar si el alumno aprendía o no lo que sucedía por medio de juicios de valor, fundamentados en modelos o parámetros racionalistas. Respecto a la Educación Física la práctica de los profesores estuvo frecuentemente ligada a la educación tradicional. La estrategia principal de evaluación era comparar y clasificar al seleccionar el alumno en base a su desempeño físico y biométrico. A partir de las críticas hechas a este modelo tradicional, desde el inicio de los años ochenta se procuró construir nuevas estrategias evaluativas relacionadas con modelos de enseñanza en torno a una perspectiva ampliada de la educación. Frente a las dificultades socio-político-económicas y a la formación pedagógica encontradas en Brasil, solamente a partir de la mitad de los años noventa, con la lucha por la instauración de la democracia y la autonomía de la escuela, hubo la posibilidad concreta de elaborar colectivamente propuestas curriculares. ; Cataluña ; Universitat de les Illes Balears. Redined Balears; Edifici Guillem Cifre de Colonya. Ctra. de Valldemossa, Km 7,5; 07122 Palma; +34971172792; +34971173190; redined.balears@uib.es ; ESP