A. Kouchner

Paris Diderot University, Lutetia Parisorum, Île-de-France, France

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Publications (102)266.55 Total impact

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    S. Croft · D. L. Kaplan · S. J. Tingay · T. Murphy · M. E. Bell · A. Rowlinson · S. Adrián-Martínez · M. Ageron · A. Albert · M. André · [...] · D. Vivolo · S. Wagner · J. Wilms · J. D. Zornoza · J. Zúñiga · A. Klotz · M. Boer · A. Le Van Suu · C. Akerlof · W. Zheng ·
    [Show abstract] [Hide abstract] ABSTRACT: We present a search, using the Murchison Widefield Array (MWA), for electromagnetic (EM) counterparts to two candidate high-energy neutrino events detected by the ANTARES neutrino telescope in 2013 November and 2014 March. These events were selected by ANTARES because they are consistent, within 04, with the locations of galaxies within 20 Mpc of Earth. Using MWA archival data at frequencies between 118 and 182 MHz, taken ~20 days prior to, at the same time as, and up to a year after the neutrino triggers, we look for transient or strongly variable radio sources that are consistent with the neutrino positions. No such counterparts are detected, and we set a 5σ upper limit for low-frequency radio emission of ~1037 erg s−1 for progenitors at 20 Mpc. If the neutrino sources are instead not in nearby galaxies, but originate in binary neutron star coalescences, our limits place the progenitors at z 0.2. While it is possible, due to the high background from atmospheric neutrinos, that neither event is astrophysical, the MWA observations are nevertheless among the first to follow up neutrino candidates in the radio, and illustrate the promise of wide-field instruments like MWA for detecting EM counterparts to such events.
    Full-text · Article · Mar 2016
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    ANTARES collaboration · S. Adrián-Martínez · A. Albert · M. André · G. Anton · M. Ardid · J. -J. Aubert · T. Avgitas · B. Baret · J. Barrios-Martí · [...] · M. Tselengidou · D. Turpin · B. Vallage · C. Vallée · V. Van Elewyck · D. Vivolo · S. Wagner · J. Wilms · J.D. Zornoza · J. Zúñiga ·
    [Show abstract] [Hide abstract] ABSTRACT: A search for muon neutrinos originating from dark matter annihilations in the Sun is performed using the data recorded by the ANTARES neutrino telescope from 2007 to 2012. In order to obtain the best possible sensitivities to dark matter signals, an optimisation of the event selection criteria is performed taking into account the background of atmospheric muons, atmospheric neutrinos and the energy spectra of the expected neutrino signals. No significant excess over the background is observed and $90\%$ C.L. upper limits on the neutrino flux, the spin--dependent and spin--independent WIMP-nucleon cross--sections are derived for WIMP masses ranging from $ \rm 50$ GeV to $\rm 5$ TeV for the annihilation channels $\rm WIMP + WIMP \to b \bar b, W^+ W^-$ and $\rm \tau^+ \tau^-$.
    Full-text · Article · Mar 2016 · Physics Letters B
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    S. Adrián-Martínez · A. Albert · M. André · G. Anton · M. Ardid · J. -J. Aubert · T. Avgitas · B. Baret · J. Barrios-Martí · S. Basa · [...] · D. Turpin · C. Tönnis · B. Vallage · C. Vallée · V. Van Elewyck · D. Vivolo · S. Wagner · J. Wilms · J.D. Zornoza · J. Zúñiga ·
    [Show abstract] [Hide abstract] ABSTRACT: A search for Secluded Dark Matter annihilation in the Sun using 2007-2012 data of the ANTARES neutrino telescope is presented. Three different cases are considered: a) detection of dimuons that result from the decay of the mediator, or neutrino detection from: b) mediator that decays into a dimuon and, in turn, into neutrinos, and c) mediator that decays directly into neutrinos. As no significant excess over background is observed, constraints are derived on the dark matter mass and the lifetime of the mediator.
    Full-text · Article · Feb 2016 · Journal of Cosmology and Astroparticle Physics
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    [Show abstract] [Hide abstract] ABSTRACT: We present the high-energy-neutrino follow-up observations of the first gravitational wave transient GW150914 observed by the Advanced LIGO detectors on Sept. 14th, 2015. We search for coincident neutrino candidates within the data recorded by the IceCube and ANTARES neutrino detectors. A possible joint detection could be used in targeted electromagnetic follow-up observations, given the significantly better angular resolution of neutrino events compared to gravitational waves. We find no neutrino candidates in both temporal and spatial coincidence with the gravitational wave event. Within 500 s of the gravitational wave event, the number of neutrino candidates detected by IceCube and ANTARES were three and zero, respectively. This is consistent with the expected atmospheric background, and none of the neutrino candidates were directionally coincident with GW150914. We use this non-detection to constrain neutrino emission from the gravitational-wave event.
    Full-text · Article · Feb 2016
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    S. Adrián-Martínez · A. Albert · M. André · M. Anghinolfi · G. Anton · M. Ardid · J. -J. Aubert · T. Avgitas · B. Baret · J. Barrios-Martí · [...] · C. Tönnis · B. Vallage · C. Vallée · V. Van Elewyck · E. Visser · D. Vivolo · S. Wagner · J. Wilms · J. D. Zornoza · J. Zúñiga ·
    [Show abstract] [Hide abstract] ABSTRACT: Compelling evidence for the existence of astrophysical neutrinos has been reported by the IceCube collaboration. Some features of the energy and declination distributions of IceCube events hint at a North/South asymmetry of the neutrino flux. This could be due to the presence of the bulk of our Galaxy in the Southern hemisphere. The ANTARES neutrino telescope, located in the Mediterranean Sea, has been taking data since 2007. It offers the best sensitivity to muon neutrinos produced by galactic cosmic ray interactions in this region of the sky. In this letter a search for an extended neutrino flux from the Galactic Ridge region is presented. Different models of neutrino production by cosmic ray propagation are tested. No excess of events is observed and upper limits for different neutrino flux spectral indices are set. This constrains the number of IceCube events possibly originating from the Galactic Ridge. A simple power-law extrapolation of the Fermi-LAT flux to associated IceCube High Energy Starting Events is excluded at 90% confidence level.
    Full-text · Article · Feb 2016
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    S. Adrián-Martínez · M. Ageron · F. Aharonian · S. Aiello · A. Albert · F. Ameli · E. Anassontzis · M. Andre · G. Androulakis · M. Anghinolfi · [...] · S. Viola · D. Vivolo · M. Volkert · G. Voulgaris · L. Wiggers · J. Wilms · E. de Wolf · K. Zachariadou · J. D. Zornoza · J. Zúñiga ·
    [Show abstract] [Hide abstract] ABSTRACT: The main objectives of the KM3NeT Collaboration are i) the discovery and subsequent observation of high-energy neutrino sources in the Universe and ii) the determination of the mass hierarchy of neutrinos. These objectives are strongly motivated by two recent important discoveries, namely: 1) The high-energy astrophysical neutrino signal reported by IceCube and 2) the sizable contribution of electron neutrinos to the third neutrino mass eigenstate as reported by Daya Bay, Reno and others. To meet these objectives, the KM3NeT Collaboration plans to build a new Research Infrastructure consisting of a network of deep-sea neutrino telescopes in the Mediterranean Sea. A phased and distributed implementation is pursued which maximises the access to regional funds, the availability of human resources and the synergetic opportunities for the earth and sea sciences community. Three suitable deep-sea sites are identified, namely off-shore Toulon (France), Capo Passero (Italy) and Pylos (Greece). The infrastructure will consist of three so-called building blocks. A building block comprises 115 strings, each string comprises 18 optical modules and each optical module comprises 31 photo-multiplier tubes. Each building block thus constitutes a 3-dimensional array of photo sensors that can be used to detect the Cherenkov light produced by relativistic particles emerging from neutrino interactions. Two building blocks will be configured to fully explore the IceCube signal with different methodology, improved resolution and complementary field of view, including the Galactic plane. One building block will be configured to precisely measure atmospheric neutrino oscillations.
    Full-text · Article · Jan 2016
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    Alexis Coleiro · Rodrigo Gracia Ruiz · Antoine Kouchner
    Preview · Article · Jan 2016 · The European Physical Journal Conferences
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    [Show abstract] [Hide abstract] ABSTRACT: We present the results of searches for point-like sources of neutrinos based on the first combined analysis of data from both the ANTARES and IceCube neutrino telescopes. The combination of both detectors which differ in size and location forms a window in the Southern sky where the sensitivity to point sources improves by up to a factor of two compared to individual analyses. Using data recorded by ANTARES from 2007 to 2012, and by IceCube from 2008 to 2011, we search for sources of neutrino emission both across the Southern sky and from a pre-selected list of candidate objects. No significant excess over background has been found in these searches, and flux upper limits for the candidate sources are presented for $E^{-2.5}$ and $E^{-2}$ power-law spectra with different energy cut-offs.
    Full-text · Article · Nov 2015 · The Astrophysical Journal
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    [Show abstract] [Hide abstract] ABSTRACT: A prototype detection unit of the KM3NeT deep-sea neutrino telescope has been installed at 3500m depth 80km offshore the Italian coast. KM3NeT in its final configuration will contain several hundreds of detection units. Each detection unit is a mechanical structure anchored to the sea floor, held vertical by a submerged buoy and supporting optical modules for the detection of Cherenkov light emitted by charged secondary particles emerging from neutrino interactions. This prototype string implements three optical modules with 31 photomultiplier tubes each. These optical modules were developed by the KM3NeT Collaboration to enhance the detection capability of neutrino interactions. The prototype detection unit was operated since its deployment in May 2014 until its decommissioning in July 2015. Reconstruction of the particle trajectories from the data requires a nanosecond accuracy in the time calibration. A procedure for relative time calibration of the photomultiplier tubes contained in each optical module is described. This procedure is based on the measured coincidences produced in the sea by the 40K background light and can easily be expanded to a detector with several thousands of optical modules. The time offsets between the different optical modules are obtained using LED nanobeacons mounted inside them. A set of data corresponding to 600 hours of livetime was analysed. The results show good agreement with Monte Carlo simulations of the expected optical background and the signal from atmospheric muons. An almost background-free sample of muons was selected by filtering the time correlated signals on all the three optical modules. The zenith angle of the selected muons was reconstructed with a precision of about 3{\deg}.
    Full-text · Article · Oct 2015 · European Physical Journal C
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    J. P. Yañez · A. Kouchner
    [Show abstract] [Hide abstract] ABSTRACT: Neutrino oscillations have been probed during the last few decades using multiple neutrino sources and experimental set-ups. In the recent years, very large volume neutrino telescopes have started contributing to the field. First ANTARES and then IceCube have relied on large and sparsely instrumented volumes to observe atmospheric neutrinos for combinations of baselines and energies inaccessible to other experiments. Using this advantage, the latest result from IceCube starts approaching the precision of other established technologies, and is paving the way for future detectors, such as ORCA and PINGU. These new projects seek to provide better measurements of neutrino oscillation parameters, and eventually determine the neutrino mass ordering. The results from running experiments and the potential from proposed projects are discussed in this review, emphasizing the experimental challenges involved in the measurements.
    Preview · Article · Sep 2015 · Advances in High Energy Physics
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    [Show abstract] [Hide abstract] ABSTRACT: High-energy neutrinos could be produced in the interaction of charged cosmic rays with matter or radiation surrounding astrophysical sources. Even with the recent detection of extraterrestrial high-energy neutrinos by the IceCube experiment, no astrophysical neutrino source has yet been discovered. Transient sources, such as gamma-ray bursts, core-collapse supernovae, or active galactic nuclei are promising candidates. Multi-messenger programs offer a unique opportunity to detect these transient sources. By combining the information provided by the ANTARES neutrino telescope with information coming from other observatories, the probability of detecting a source is enhanced, allowing the possibility of identifying a neutrino progenitor from a single detected event. A method based on optical and X-ray follow-ups of high-energy neutrino alerts has been developed within the ANTARES collaboration. This method does not require any assumptions on the relation between neutrino and photon spectra other than time-correlation. This program, denoted as TAToO, triggers a network of robotic optical telescopes (TAROT and ROTSE) and the Swift-XRT with a delay of only a few seconds after a neutrino detection, and is therefore well-suited to search for fast transient sources. To identify an optical or X-ray counterpart to a neutrino signal, the images provided by the follow-up observations are analysed with dedicated pipelines. A total of 42 alerts with optical and 7 alerts with X-ray images taken with a maximum delay of 24 hours after the neutrino trigger have been analysed. No optical or X-ray counterparts associated to the neutrino triggers have been found, and upper limits on transient source magnitudes have been derived. The probability to reject the gamma-ray burst origin hypothesis has been computed for each alert.
    Full-text · Article · Aug 2015 · Journal of Cosmology and Astroparticle Physics
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    [Show abstract] [Hide abstract] ABSTRACT: The ANTARES experiment consists of an array of photomultipliers distributed along 12 lines and located deep underwater in the Mediterranean Sea. It searches for astrophysical neutrinos collecting the Cherenkov light induced by the charged particles, mainly muons, produced in neutrino interactions around the detector. Since at energies of $\sim$10 TeV the muon and the incident neutrino are almost collinear, it is possible to use the ANTARES detector as a neutrino telescope and identify a source of neutrinos in the sky starting from a precise reconstruction of the muon trajectory. To get this result, the arrival times of the Cherenkov photons must be accurately measured. A to perform time calibrations with the precision required to have optimal performances of the instrument is described. The reconstructed tracks of the atmospheric muons in the ANTARES detector are used to determine the relative time offsets between photomultipliers. Currently, this method is used to obtain the time calibration constants for photomultipliers on different lines at a precision level of 0.5 ns. It has also been validated for calibrating photomultipliers on the same line, using a system of LEDs and laser light devices.
    Full-text · Article · Jul 2015
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    [Show abstract] [Hide abstract] ABSTRACT: The ANTARES telescope is well-suited for detecting astrophysical transient neutrino sources as it can observe a full hemisphere of the sky at all times with a high duty cycle. The background due to atmospheric particles can be drastically reduced, and the point-source sensitivity improved, by selecting a narrow time window around possible neutrino production periods. Blazars, being radio-loud active galactic nuclei with their jets pointing almost directly towards the observer, are particularly attractive potential neutrino point sources, since they are among the most likely sources of the very high-energy cosmic rays. Neutrinos and gamma rays may be produced in hadronic interactions with the surrounding medium. Moreover, blazars generally show high time variability in their light curves at different wavelengths and on various time scales. This paper presents a time-dependent analysis applied to a selection of flaring gamma-ray blazars observed by the FERMI/LAT experiment and by TeV Cherenkov telescopes using five years of ANTARES data taken from 2008 to 2012. The results are compatible with fluctuations of the background. Upper limits on the neutrino fluence have been produced and compared to the measured gamma-ray spectral energy distribution.
    Full-text · Article · Jun 2015
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    [Show abstract] [Hide abstract] ABSTRACT: A search for high-energy neutrinos coming from the direction of the Galactic Centre is performed using the data recorded by the ANTARES neutrino telescope from 2007 to 2012. The event selection criteria are chosen to maximise the sensitivity to possible signals produced by the self-annihilation of weakly interacting massive particles accumulated around the centre of the Milky Way with respect to the atmospheric background. After data unblinding, the number of neutrinos observed in the line of sight of the Galactic Centre is found to be compatible with background expectations. The 90% C.L. upper limits in terms of the neutrino+anti-neutrino flux, $\rm \Phi_{\nu_{\mu}+\bar{\nu}_\mu}$, and the velocity averaged annihilation cross-section, $\rm <\sigma_{A}v>$, are derived for the WIMP self-annihilation channels into $\rm b\bar{b},W^{+}W^{-},\tau^{+}\tau^{-},\mu^{+}\mu^{-},\nu\bar{\nu}$. The ANTARES limits for $\rm <\sigma_{A}v>$ are shown to be the most stringent for a neutrino telescope over the WIMP masses $\rm 25\,GeV < M_{WIMP} < 10\,TeV$.
    Full-text · Article · May 2015 · Journal of Cosmology and Astroparticle Physics
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    [Show abstract] [Hide abstract] ABSTRACT: The source(s) of the neutrino excess reported by the IceCube Collaboration is unknown. The TANAMI Collaboration recently reported on the multiwavelength emission of six bright, variable blazars which are positionally coincident with two of the most energetic IceCube events. Such objects are prime candidates to be the source of the highest-energy cosmic rays, and thus of associated neutrino emission. We present an analysis of neutrino emission from the six blazars using observations with the ANTARES neutrino telescope. The standard methods of the ANTARES candidate list search are applied to six years of data to search for an excess of muons - and hence their neutrino progenitors - from the directions of the six blazars described by the TANAMI Collaboration, and which are possibly associated with two IceCube events. Monte Carlo simulations of the detector response to both signal and background particle fluxes are used to estimate the sensitivity of this analysis for different possible source neutrino spectra. A maximum-likelihood approach, using the reconstructed energies and arrival directions of through-going muons, is used to identify events with properties consistent with a blazar origin.Both blazars predicted to be the most neutrino-bright in the TANAMI sample (1653-329 and 1714-336) have a signal flux fitted by the likelihood analysis corresponding to approximately one event. This observation is consistent with the blazar-origin hypothesis of the IceCube event IC14 for a broad range of blazar spectra, although an atmospheric origin cannot be excluded. No ANTARES events are observed from any of the other four blazars, including the three associated with IceCube event IC20. This excludes at a 90% confidence level the possibility that this event was produced by these blazars unless the neutrino spectrum is flatter than -2.4.
    Full-text · Article · Mar 2015 · Astronomy and Astrophysics
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    [Show abstract] [Hide abstract] ABSTRACT: Context. The jets of radio-loud Active Galactic Nuclei are among the most powerful particle accelerators in the Universe, and a plausible production site for high-energy cosmic rays. The detection of high-energy neutrinos from these sources would provide unambiguous evidence of a hadronic component in such jets. High-luminosity blazars, such as the flat-spectrum radio quasars (FSRQs), are promising candidates to search for such emission. Because of the low fluxes due to large redshift, these sources are however challenging for the current generation of neutrino telescopes such as ANTARES and IceCube. Aims. This paper proposes to exploit gravitational lensing effects to improve the sensitivity of neutrino telescopes to the intrinsic neutrino emission of distant blazars. Methods. This strategy is illustrated with a search for cosmic neutrinos in the direction of four distant and gravitationally lensed blazars, using data collected from 2007 to 2012 by ANTARES. The magnification factor is estimated for each system assuming a singular isothermal profile for the lens. The neutrino event selection and statistical analysis are identical to the already published ANTARES search for neutrino point sources, which included a few (non-lensed) FSRQs. Results. Based on ANTARES data, we derive upper limits on the intrinsic luminosity of the selected lensed sources. We obtain the strongest constraint from the lensed system B0218$+$357, providing a limit on the total neutrino luminosity of this FSRQ of $1.08\times 10^{46}\,\mathrm{erg}\,\mathrm{s}^{-1}$. This limit is about one order of magnitude lower than those obtained in the ANTARES standard point source search with non-lensed FSRQs, demonstrating the utility of the method.
    Full-text · Article · Nov 2014 · Journal of Cosmology and Astroparticle Physics
  • Antoine Kouchner
    [Show abstract] [Hide abstract] ABSTRACT: The ANTARES detector, located 40 km off the French coast, is the largest deep-sea neutrino telescope in the world. It consists of an array of 885 photomultipliers detecting the Cherenkov light induced by charged leptons produced by neutrino interactions in and around the detector. The primary goal of ANTARES is to search for astrophysical neutrinos in the TeV-PeV range. This comprises generic searches for any diffuse cosmic neutrino flux as well as more specific searches for astrophysical sources such as active galactic nuclei or galactic sources. The search program also includes multi-messenger analyses based on time and/or space coincidences with other cosmic probes. The ANTARES observatory is sensitive to a wide range of other phenomena, from atmospheric neutrino oscillations to dark matter annihilation or potential exotics such as nuclearites and magnetic monopoles. The most recent results are reported.
    No preview · Article · Oct 2014 · Brazilian Journal of Physics
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    [Show abstract] [Hide abstract] ABSTRACT: The first prototype of a photo-detection unit of the future KM3NeT neutrino telescope has been deployed in the deep waters of the Mediterranean Sea. This digital optical module has a novel design with a very large photocathode area segmented by the use of 31 three inch photomultiplier tubes. It has been integrated in the ANTARES detector for in-situ testing and validation. This paper reports on the first months of data taking and rate measurements. The analysis results highlight the capabilities of the new module design in terms of background suppression and signal recognition. The directionality of the optical module enables the recognition of multiple Cherenkov photons from the same $^{40}$K decay and the localization bioluminescent activity in the neighbourhood. The single unit can cleanly identify atmospheric muons and provide sensitivity to the muon arrival directions.
    Full-text · Article · Sep 2014 · European Physical Journal C
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    Antoine Kouchner
    [Show abstract] [Hide abstract] ABSTRACT: A short review on the next-generation experiments aiming to study the neutrinos produced in cosmic-ray induced atmospheric showers is presented. The projects currently proposed rely on different complementary detection techniques, from the successful water Cherenkov and magnetized tracko-calorimeter techniques to the more innovative Liquid Argon technology. As all of the proposed detectors must be deeply buried to mitigate the atmospheric muon background, many experiments are expected to be placed deep underground. Following the neutrino telescope approach, the largest ones will be located deep under the sea/ice. Several future projects are part of a wider physics program which includes a neutrino beam. For such cases, the focus is put on the expected performances with only using atmospheric neutrinos. The main physics thread of the review is the question of the determination of the ordering of the neutrino mass eigenstates, referred to as the neutrino mass hierarchy. This falls into the broader context of the precise measurement of the neutrino mixing parameters. The expected reach of the future planned detectors in this respect is also addressed.
    Preview · Article · Sep 2014 · Physics of the Dark Universe
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    [Show abstract] [Hide abstract] ABSTRACT: This paper reports a search for spatial clustering of the arrival directions of high energy muon neutrinos detected by the ANTARES neutrino telescope. An improved two-point correlation method is used to study the autocorrelation of 3058 neutrino candidate events as well as cross-correlations with other classes of astrophysical objects: sources of high energy gamma rays, massive black holes and nearby galaxies. No significant deviations from the isotropic distribution of arrival directions expected from atmospheric backgrounds are observed.
    Full-text · Article · May 2014 · Journal of Cosmology and Astroparticle Physics

Publication Stats

1k Citations
266.55 Total Impact Points

Institutions

  • 2012-2015
    • Paris Diderot University
      • AstroParticule et Cosmologie (APC) UMR 7164
      Lutetia Parisorum, Île-de-France, France
  • 2013
    • University of Paris-Est
      La Haye-Descartes, Centre, France
  • 2011-2013
    • French National Centre for Scientific Research
      Lutetia Parisorum, Île-de-France, France
    • AstroParticle and Cosmology Laboratory
      Lutetia Parisorum, Île-de-France, France
    • Leiden University
      Leyden, South Holland, Netherlands
  • 2009-2013
    • Université Paris 13 Nord
      Вильтанез, Île-de-France, France
  • 2005-2011
    • Friedrich-Alexander Universität Erlangen-Nürnberg
      Erlangen, Bavaria, Germany
  • 2007
    • Cea Leti
      Grenoble, Rhône-Alpes, France
  • 2001
    • The University of Sheffield
      • Department of Physics and Astronomy
      Sheffield, England, United Kingdom