95 research outputs found
Search for muon neutrinos from gamma-ray bursts with the ANTARES neutrino telescope using 2008 to 2011 data
Aims. We search for muon neutrinos in coincidence with GRBs with the ANTARES neutrino detector using data from the end of 2007 to 2011.
Methods. Expected neutrino fluxes were calculated for each burst individually. The most recent numerical calculations of the spectra using the NeuCosmA code were employed, which include Monte Carlo simulations of the full underlying photohadronic interaction processes. The discovery probability for a selection of 296 GRBs in the given period was optimised using an extended maximum-likelihood strategy.
Results. No significant excess over background is found in the data, and 90% confidence level upper limits are placed on the total expected flux according to the modelPostprint (published version
Measurement of the cosmic ray spectrum above eV using inclined events detected with the Pierre Auger Observatory
A measurement of the cosmic-ray spectrum for energies exceeding
eV is presented, which is based on the analysis of showers
with zenith angles greater than detected with the Pierre Auger
Observatory between 1 January 2004 and 31 December 2013. The measured spectrum
confirms a flux suppression at the highest energies. Above
eV, the "ankle", the flux can be described by a power law with
index followed by
a smooth suppression region. For the energy () at which the
spectral flux has fallen to one-half of its extrapolated value in the absence
of suppression, we find
eV.Comment: Replaced with published version. Added journal reference and DO
Energy Estimation of Cosmic Rays with the Engineering Radio Array of the Pierre Auger Observatory
The Auger Engineering Radio Array (AERA) is part of the Pierre Auger
Observatory and is used to detect the radio emission of cosmic-ray air showers.
These observations are compared to the data of the surface detector stations of
the Observatory, which provide well-calibrated information on the cosmic-ray
energies and arrival directions. The response of the radio stations in the 30
to 80 MHz regime has been thoroughly calibrated to enable the reconstruction of
the incoming electric field. For the latter, the energy deposit per area is
determined from the radio pulses at each observer position and is interpolated
using a two-dimensional function that takes into account signal asymmetries due
to interference between the geomagnetic and charge-excess emission components.
The spatial integral over the signal distribution gives a direct measurement of
the energy transferred from the primary cosmic ray into radio emission in the
AERA frequency range. We measure 15.8 MeV of radiation energy for a 1 EeV air
shower arriving perpendicularly to the geomagnetic field. This radiation energy
-- corrected for geometrical effects -- is used as a cosmic-ray energy
estimator. Performing an absolute energy calibration against the
surface-detector information, we observe that this radio-energy estimator
scales quadratically with the cosmic-ray energy as expected for coherent
emission. We find an energy resolution of the radio reconstruction of 22% for
the data set and 17% for a high-quality subset containing only events with at
least five radio stations with signal.Comment: Replaced with published version. Added journal reference and DO
Measurement of the Radiation Energy in the Radio Signal of Extensive Air Showers as a Universal Estimator of Cosmic-Ray Energy
We measure the energy emitted by extensive air showers in the form of radio
emission in the frequency range from 30 to 80 MHz. Exploiting the accurate
energy scale of the Pierre Auger Observatory, we obtain a radiation energy of
15.8 \pm 0.7 (stat) \pm 6.7 (sys) MeV for cosmic rays with an energy of 1 EeV
arriving perpendicularly to a geomagnetic field of 0.24 G, scaling
quadratically with the cosmic-ray energy. A comparison with predictions from
state-of-the-art first-principle calculations shows agreement with our
measurement. The radiation energy provides direct access to the calorimetric
energy in the electromagnetic cascade of extensive air showers. Comparison with
our result thus allows the direct calibration of any cosmic-ray radio detector
against the well-established energy scale of the Pierre Auger Observatory.Comment: Replaced with published version. Added journal reference and DOI.
Supplemental material in the ancillary file
Search for muon neutrinos from gamma-ray bursts with the ANTARES neutrino telescope using 2008 to 2011 data
9 pages, 8 figures; added Fig. 1 with effective area, updated Fig. 8 (b) according to arXiv:1204.4219 ; Références publication Astron Astrophys 559 (2013) A9International audienceAims. We search for muon neutrinos in coincidence with GRBs with the ANTARES neutrino detector using data from the end of 2007 to 2011. Methods. Expected neutrino fluxes were calculated for each burst individually. The most recent numerical calculations of the spectra using the NeuCosmA code were employed, which include Monte Carlo simulations of the full underlying photohadronic interaction processes. The discovery probability for a selection of 296 GRBs in the given period was optimised using an extended maximum-likelihood strategy. Results. No significant excess over background is found in the data, and 90% confidence level upper limits are placed on the total expected flux according to the model
Recherche de neutrinos issus de sources transitoires avec le télescope à neutrinos ANTARES et leur suivi optique- Développement de photomultiplicateurs hémisphériques hybrides pour les expériences en Astroparticules
Astroparticle experiments are being developed with the aim of resolving the mystery of cosmic rays. Questions like from where cosmic rays originate or how do they get accelerated up to ultra high energies are still unresolved. Cherenkov telescopes like ANTARES detect the Cherenkov light emitted by muons propagating in sea water. Muons are produced by the interaction of cosmic neutrinos (signal) or atmospheric neutrinos (noise) with the Earth nuclei. In order to offer the best detection conditions of Cherenkov light, and subsequently ensure a good reconstruction quality of the muons trajectory, the light sensors i.e the photomultipliers must satisfy various conditions.The first part of this thesis focuses on the development of photomultipliers using crystals as a preamplifier of the light signal. The advantage of such a method is the possibility to separate individual photo-electrons and to enhance the temporal resolution by applying a high electric field. The design and conception as well as the possibility to produce such devices at large industrial scales is for the first time developed in this thesis.The second part of the thesis is inspired from the new multi-messenger approach in ANTARES. An optical follow-up with six telescopes spread over the two hemispheres is triggered by the detection of a high energy neutrino or a set of neutrinos coincident in time and direction. Such a system enhances the sensitivity to transient sources such as Gamma Rays Bursts or Core Collapse Supernovae. The neutrino alert system is now fully operational. The system offers good performances; the optical follow-up starts within one minute from the neutrino detection and the median angular accuracy of the reconstructed neutrinos is 0.4âŠ. Upon the reception of an alert, the telescopes point at the neutrino direction and start the acquisition of image series almost each night of the month follow- ing the neutrino alert. Image analysis tools have been implemented to search for optical transients and first results on the search of GRB optical counterparts correlated with a neutrino signal are presented.Lâorigine des rayons cosmiques ainsi que les procĂ©dĂ©s mis en oeuvre dans leur accĂ©lĂ©ration Ă dâultra-hautes Ă©nergies constituent lâun des sujets les plus dĂ©battus en astrophysique de nos jours. Une clĂ© de ce mystĂšre peut se trouver dans la dĂ©tection de neutrinos cosmiques produits par un panel dâobjets astrophysiques candidats Ă lâĂ©mission de rayons cosmiques. Les tĂ©lescopes Ă neutrinos tels que ANTARES dĂ©tectent la lumiĂšre Cherenkov issue des muons se propageant dans lâeau de mer. Les muons sont les produits dâinteraction de neutrinos cosmiques (signal) ou atmosphĂ©riques (bruit) avec les noyaux de la terre. Pour offrir les meilleures conditions de dĂ©tection de la lumiĂšre Cherenkov, et par consĂ©quent bien reconstruire les traces des muons dĂ©tectĂ©s, les dĂ©tecteurs de lumiĂšre i.e les photo- multiplicateurs dont sont Ă©quipĂ©s les expĂ©riences Cherenkov dans la mer ou dans la glace doivent satisfaire plusieurs conditions, telles quâune bonne rĂ©solution temporelle et un bon signal-sur-bruit pour pouvoir sĂ©parer les pics photo-Ă©lectrons.Le premier volet de cette thĂšse porte sur le dĂ©veloppement de photomultiplicateurs utilisant le cristal comme prĂ©amplificateur de signal optique. Lâavantage dâun tel procĂ©dĂ© est la possibilitĂ© de sĂ©parer plusieurs pics photo-Ă©lectrons et dâamĂ©liorer la rĂ©solution tem- porelle grĂące Ă lâapplication dâun fort champ Ă©lectrique. La conception dâun tel prototype et la possibilitĂ© de son industrialisation Ă grande Ă©chelle sont dĂ©veloppĂ©s pour la premiĂšre fois dans cette thĂšse.Le deuxiĂšme volet sâinscrit dans la nouvelle thĂ©matique multi-messagers dâANTARES. Un suivi avec six tĂ©lescopes optiques rĂ©partis sur chaque hĂ©misphĂšre est dĂ©clenchĂ© lorsque ANTARES dĂ©tecte un neutrino de haute Ă©nergie ou un ensemble de neutrinos coĂŻncidents en temps et en direction. Un tel systĂšme permet dâaugmenter la sensibilitĂ© de dĂ©tection de neutrinos provenant de sources transitoires tels que les sursauts gamma et les SupernovĂŠ Ă effondrement de cĆur. Un systĂšme dâalertes neutrino est maintenant implĂ©mentĂ© et fonctionne continument et de maniĂšre autonome dans ANTARES. Le systĂšme offre de bonnes performances; le suivi optique se dĂ©clenche dans la minute suivant la dĂ©tection neutrino et lâincertitude sur la reconstruction de la trajectoire du neutrino est de 0.4⊠(valeur mĂ©diane). Une fois lâalerte reçue par un des tĂ©lescopes, celui-ci se repositionne sur la direction du neutrino et entame une sĂ©rie dâobservations rĂ©parties sur le mois suivant lâalerte. Cette thĂšse a portĂ© dans un premier temps sur lâaspect neutrino en dĂ©veloppant le filtre sĂ©lectionnant les Ă©vĂšnements haute Ă©nergie et multi-neutrinos. Des outils dâanalyse dâimages optiques ont ensuite Ă©tĂ© implĂ©mentĂ©s pour la recherche de sources transitoires. Les premiers rĂ©sultats de recherche de contreparties optiques de sursauts gamma en corrĂ©lation avec un signal neutrino sont prĂ©sentĂ©s
Indications of anisotropy at large angular scales in the arrival directions of cosmic rays detected at the Pierre Auger Observatory
International audienc
Arrival direction distribution of cosmic rays from 100 PeV to the highest energies detected at the Pierre Auger Observatory
International audienceAt the Pierre Auger Observatory, several searches for anisotropies in the distribution of arrival directions of cosmic rays detected above 100 PeV are being undertaken. Although no significant deviation from isotropy has been revealed at present, some measurements related to the angular distributions at large scales are suggestive of dipole patterns of small amplitudes over a wide energy range. Upper limits on the dipole and quadrupole moments derived from these analyses are presented. They constrain scenarios in which cosmic rays could originate from stationary Galactic sources emitting in all directions up to the ankle energy
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