41 research outputs found
Status and Recent Results of the Acoustic Neutrino Detection Test System AMADEUS
The AMADEUS system is an integral part of the ANTARES neutrino telescope in
the Mediterranean Sea. The project aims at the investigation of techniques for
acoustic neutrino detection in the deep sea. Installed at a depth of more than
2000m, the acoustic sensors of AMADEUS are based on piezo-ceramics elements for
the broad-band recording of signals with frequencies ranging up to 125kHz.
AMADEUS was completed in May 2008 and comprises six "acoustic clusters", each
one holding six acoustic sensors that are arranged at distances of roughly 1m
from each other. The clusters are installed with inter-spacings ranging from
15m to 340m. Acoustic data are continuously acquired and processed at a
computer cluster where online filter algorithms are applied to select a
high-purity sample of neutrino-like signals. 1.6 TB of data were recorded in
2008 and 3.2 TB in 2009. In order to assess the background of neutrino-like
signals in the deep sea, the characteristics of ambient noise and transient
signals have been investigated. In this article, the AMADEUS system will be
described and recent results will be presented.Comment: 7 pages, 8 figures. Proceedings of ARENA 2010, the 4th International
Workshop on Acoustic and Radio EeV Neutrino Detection Activitie
The ANTARES Telescope Neutrino Alert System
The ANTARES telescope has the capability to detect neutrinos produced in
astrophysical transient sources. Potential sources include gamma-ray bursts,
core collapse supernovae, and flaring active galactic nuclei. To enhance the
sensitivity of ANTARES to such sources, a new detection method based on
coincident observations of neutrinos and optical signals has been developed. A
fast online muon track reconstruction is used to trigger a network of small
automatic optical telescopes. Such alerts are generated for special events,
such as two or more neutrinos, coincident in time and direction, or single
neutrinos of very high energy.Comment: 17 pages, 9 figures submitted to Astroparticle Physic
Acoustic and optical variations during rapid downward motion episodes in the deep north-western Mediterranean Sea
An Acoustic Doppler Current Profiler (ADCP) was moored at the deep-sea site
of the ANTARES neutrino telescope near Toulon, France, thus providing a unique
opportunity to compare high-resolution acoustic and optical observations
between 70 and 170 m above the sea bed at 2475 m. The ADCP measured downward
vertical currents of magnitudes up to 0.03 m s-1 in late winter and early
spring 2006. In the same period, observations were made of enhanced levels of
acoustic reflection, interpreted as suspended particles including zooplankton,
by a factor of about 10 and of horizontal currents reaching 0.35 m s-1. These
observations coincided with high light levels detected by the telescope,
interpreted as increased bioluminescence. During winter 2006 deep dense-water
formation occurred in the Ligurian subbasin, thus providing a possible
explanation for these observations. However, the 10-20 days quasi-periodic
episodes of high levels of acoustic reflection, light and large vertical
currents continuing into the summer are not direct evidence of this process. It
is hypothesized that the main process allowing for suspended material to be
moved vertically later in the year is local advection, linked with topographic
boundary current instabilities along the rim of the 'Northern Current'.Comment: 30 pages, 7 figure
Perceptions of teachers and directors about the factors that promote or constrain environmental education in schools of Metropolitan Area of Buenos Aires, Argentina
El trabajo aborda las percepciones de docentes y directores de escuelas acerca delos factores que promueven u obstaculizan una educación ambiental compleja, generadora de conocimientos, con dispositivos participativos y orientados a la equidad en instituciones educativas del Área Metropolitana de Buenos Aires (Argentina). Como resultado se observaron experiencias heterogéneas y voluntad de instalar nuevas prácticas, pero con factores que limitan el cambio: pautas culturales arraigadas; deficiencias en la capacitación docente, en cuanto a las políticas públicas; poca claridad en las definiciones sobre los objetivos de la educación ambiental, su abordaje curricular y los dispositivos pedagógicos. Prevalecen enfoques fragmentados, naturalistas y la ausencia de una visión crítica. A nivel institucional, se discute lapertinencia de implementar prácticas sustentables en el aula. Las propias percepciones también operan como obstáculos. Todo esto dificulta la adopción de nuevas acciones de educación ambiental con el ímpetu necesario para sostenerlas en el tiempo.The paper examines the perceptions of teachers and directors regarding the factors that promote or constrain complex environmental education, which generates knowledge, with participatory devices and oriented to equity in educational institutions in Metropolitan Area of Buenos Aires (Argentina). As result, we detected heterogeneous experiences and willingness to set new practices up. But there are factors limiting the change: deep-rooted cultural customs; shortcomings in terms of teacher training; in public policies a lack of clarity about environmental education objectives, curricular approach and pedagogical devices. Fragmented and naturalists approaches, and lack of a critical perspective prevail. At the institutional level, the relevance of implementing sustainable practices in classroom is discussed. Perceptions also operate as obstacles. All this hinders the adoption of new environmental education actions and the momentum needed to sustain them over time.Fil: Saidon, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires; ArgentinaFil: Claverie, Julieta Andrea. Universidad Nacional de Tres de Febrero. Nucleo Interd de Formación y Est P/e/des D/l/educ; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
A method for detection of muon induced electromagnetic showers with the ANTARES detector
The primary aim of ANTARES is neutrino astronomy with upward going muons
created in charged current muon neutrino interactions in the detector and its
surroundings. Downward going muons are background for neutrino searches. These
muons are the decay products of cosmic-ray collisions in the Earth's atmosphere
far above the detector. This paper presents a method to identify and count
electromagnetic showers induced along atmospheric muon tracks with the ANTARES
detector. The method is applied to both cosmic muon data and simulations and
its applicability to the reconstruction of muon event energies is demonstrated.Comment: 20 pages, 7 figure
Measurement of the Group Velocity of Light in Sea Water at the ANTARES Site
The group velocity of light has been measured at eight different wavelengths
between 385 nm and 532 nm in the Mediterranean Sea at a depth of about 2.2 km
with the ANTARES optical beacon systems. A parametrisation of the dependence of
the refractive index on wavelength based on the salinity, pressure and
temperature of the sea water at the ANTARES site is in good agreement with
these measurements.Comment: 14 pages, 5 figure
Search for neutrino emission from gamma-ray flaring blazars with the ANTARES telescope
The ANTARES telescope is well-suited to detect neutrinos produced in astrophysical transient sources as it can observe a full hemisphere of the sky at all times with a high duty cycle. Radio-loud active galactic nuclei with jets pointing almost directly towards the observer, the so-called blazars, are particularly attractive potential neutrino point sources. The all-sky monitor LAT on board the Fermi satellite probes the variability of any given gamma-ray bright blazar in the sky on time scales of hours to months. Assuming hadronic models, a strong correlation between the gamma-ray and the neutrino fluxes is expected. Selecting a narrow time window on the assumed neutrino production period can significantly reduce the background.
An unbinned method based on the minimization of a likelihood ratio was applied to a subsample of data collected in 2008 (61 days live time). By searching for neutrinos during the high state periods of the AGN light curve, the sensitivity to these sources was improved by about a factor of two with respect to a standard time-integrated point source search. First results on the search for neutrinos associated with ten bright and variable Fermi sources are presented.The authors acknowledge the financial support of the funding agencies: Centre National de la Recherche Scientifique (CNRS), Commissariat a l'energie atomique et aux energies alternatives (CEA), Agence National de la Recherche (ANR), Commission Europeenne (FEDER fund and Marie Curie Program), Region Alsace (contrat CPER), Region Provence-Alpes-Cote d'Azur, Departement du Var and Ville de La Seyne-sur-Mer, France; Bundesministerium fur Bildung und Forschung (BMBF), Germany; Istituto Nazionale di Fisica Nucleare (INFN), Italy; Stichting voor Fundamenteel Onderzoek der Materie (FOM), Nederlandse organisatie voor Wetenschappelijk Onderzoek (NWO), the Netherlands; Council of the President of the Russian Federation for young scientists and leading scientific schools supporting grants, Russia; National Authority for Scientific Research (ANCS), Romania; Ministerio de Ciencia e Innovacion (MICINN), Prometeo of Generalitat Valenciana and MultiDark, Spain. We also acknowledge the technical support of Werner, AIM and Foselev Marine for the sea operation and the CC-IN2P3 for the computing facilities.Adrián Martínez, S.; Al Samarai, I.; Albert, A.; André, M.; Anghinolfi, M.; Anton, G.; Anvar, S.... (2012). Search for neutrino emission from gamma-ray flaring blazars with the ANTARES telescope. Astroparticle Physics. 36(1):204-210. https://doi.org/10.1016/j.astropartphys.2012.06.001S20421036
Spread of a SARS-CoV-2 variant through Europe in the summer of 2020.
Following its emergence in late 2019, the spread of SARS-CoV-21,2 has been tracked by phylogenetic analysis of viral genome sequences in unprecedented detail3–5. Although the virus spread globally in early 2020 before borders closed, intercontinental travel has since been greatly reduced. However, travel within Europe resumed in the summer of 2020. Here we report on a SARS-CoV-2 variant, 20E (EU1), that was identified in Spain in early summer 2020 and subsequently spread across Europe. We find no evidence that this variant has increased transmissibility, but instead demonstrate how rising incidence in Spain, resumption of travel, and lack of effective screening and containment may explain the variant’s success. Despite travel restrictions, we estimate that 20E (EU1) was introduced hundreds of times to European countries by summertime travellers, which is likely to have undermined local efforts to minimize infection with SARS-CoV-2. Our results illustrate how a variant can rapidly become dominant even in the absence of a substantial transmission advantage in favourable epidemiological settings. Genomic surveillance is critical for understanding how travel can affect transmission of SARS-CoV-2, and thus for informing future containment strategies as travel resumes. © 2021, The Author(s), under exclusive licence to Springer Nature Limited
Search for a diffuse flux of high-energy with the ANTARES neutrino telescope
A search for a diffuse flux of astrophysical muon neutrinos, using data
collected by the ANTARES neutrino telescope is presented. A
sr sky was monitored for a total of 334 days of equivalent live time. The
searched signal corresponds to an excess of events, produced by astrophysical
sources, over the expected atmospheric neutrino background. The observed number
of events is found compatible with the background expectation. Assuming an
flux spectrum, a 90% c.l. upper limit on the diffuse flux of
E^2\Phi_{90%} = 5.3 \times 10^{-8} \ \mathrm{GeV\ cm^{-2}\ s^{-1}\ sr^{-1}}
in the energy range 20 TeV - 2.5 PeV is obtained. Other signal models with
different energy spectra are also tested and some rejected.Comment: 14 pages, 6 figure
ANTARES: the first undersea neutrino telescope
The ANTARES Neutrino Telescope was completed in May 2008 and is the first
operational Neutrino Telescope in the Mediterranean Sea. The main purpose of
the detector is to perform neutrino astronomy and the apparatus also offers
facilities for marine and Earth sciences. This paper describes the design, the
construction and the installation of the telescope in the deep sea, offshore
from Toulon in France. An illustration of the detector performance is given