Giulia De Bonis - Academia.edu (original) (raw)

Papers by Giulia De Bonis

Astroparticle Physics, 2016

ABSTRACT The ANTARES experiment consists of an array of photomultipliers distributed along 12 lin... more 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\simsim10 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.

Journal of Cosmology and Astroparticle Physics, 2016

optical or X-ray counterparts associated to the neutrino triggers have been found, and upper limi... more 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.

Astronomy & Astrophysics, 2015

The source(s) of the neutrino excess reported by the IceCube Collaboration is unknown. The TANAMI... more 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

Ocean Science Discussions, 2010

... K. Fratini 24,3 , U. Fritsch 4 , J.-L. Fuda 22 , G. Giacomelli 11,12 , JP G ómez-González 1 ,... more ... K. Fratini 24,3 , U. Fritsch 4 , J.-L. Fuda 22 , G. Giacomelli 11,12 , JP G ómez-González 1 , ... van Amsterdam, Institut voor Hoge-Energiefysika, Science Park 105, 1098 XG Amsterdam, The Netherlands 30Dipartimento di Fisica ed Astronomia dell'Universit`a, Viale Andrea Doria 6 ...

A 13-inch Optical Module (OM) containing a large-area (10-inch) photomultiplier was designed as p... more A 13-inch Optical Module (OM) containing a large-area (10-inch) photomultiplier was designed as part of Phase-2 of the NEMO project. An intense R&D activity on the photomultipliers, the voltage supply boards, the optical coupling as well as the study of the influences of the Earth's magnetic field has driven the choice of each single component of the OM. Following a well-established production procedure, 32 OMs were assembled and their functionality tested. The design, the testing and the production phases are thoroughly described in this paper.

In the underwater neutrino telescopes, the positions of the Cherenkov light sensors and their mov... more In the underwater neutrino telescopes, the positions of the Cherenkov light sensors and their movements must be known with an accuracy of few tens of centimetres. In this work, the activities of the SMO and KM3NeT-Italia teams for the development of an acoustic positioning system for KM3NeT-Italia project are presented. The KM3NeT-Italia project foresees the construction, within two years, of 8 towers in the view of the several km 3 -scale neutrino telescope KM3NeT.

Journal of High Energy Astrophysics, 2014

The first prototype of a photo-detection unit of the future KM3NeT neutrino telescope has been de... more 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 localisation bioluminescent activity in the neighbourhood. The single unit can cleanly identify atmospheric muons and provide sensitivity to the muon arrival directions.

Context. The jets of radio-loud Active Galactic Nuclei are among the most powerful particle accel... more 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 × 10 46 erg 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.

IEEE Nuclear Science Symposium Conference Record, 2007

... A. D'Amico d, G. De Bonis j, C. De Marzo a, G. De Rosa n, G. De Ruvo a, R. De Vita e, C.... more ... A. D'Amico d, G. De Bonis j, C. De Marzo a, G. De Rosa n, G. De Ruvo a, R. De Vita e, C. Distefano d, E. Falchini f, V. Flaminio f, K ... V. Pappalardo d, C. Petta p, P. Piattelli d, D. Piombo e, F. Raffaelli f, G. Raia d, N. Randazzo b, S. Reito b, G. Ricco i, G. Riccobene d, M. Ripani e, A ...

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2011

The ANTARES Neutrino Telescope was completed in May 2008 and is the first operational Neutrino Te... more 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.

The Astrophysical Journal, 2012

In this paper, a time integrated search for point sources of cosmic neutrinos is presented using ... more In this paper, a time integrated search for point sources of cosmic neutrinos is presented using the data collected from 2007 to 2010 by the ANTARES neutrino telescope. No statistically significant signal has been found and upper limits on the neutrino flux have been obtained. Assuming an E −2 ν spectrum, these flux limits are at 1 − 10×10 −8 GeV cm −2 s −1 for declinations ranging from −90 • to The Netherlands -4 -40 • . Limits for specific models of RX J1713.7-3946 and Vela X, which include information on the source morphology and spectrum, are also given.

The Astrophysical Journal, 2013

This paper presents a search for correlation in the arrival directions of 2190 neutrino candidate... more This paper presents a search for correlation in the arrival directions of 2190 neutrino candidate events detected in 2007-2008 by the ANTARES telescope, and 69 ultra-high energy cosmic rays (UHECRs) observed by the Pierre Auger Observatory between January 1st 2004 and December 31st 2009. No significant correlation was found. The corresponding 90% C.L. upper limit on the neutrino flux from each observed UHECR direction (assuming an equal flux from all of them and for E −2 energy spectrum) is 4.99×10 −8 GeVcm −2 s −1 .

Physical Review Letters, 2013

Nuclear Physics B - Proceedings Supplements, 2007

... G. De Bonis i , C. De Marzo b , maltese cross , G. De Rosa g , R. De Vita e , C. Distefano a ... more ... G. De Bonis i , C. De Marzo b , maltese cross , G. De Rosa g , R. De Vita e , C. Distefano a , E. Falchini h , C. Fiorello b , V. Flaminio h , K ... V. Pappalardo a , C. Petta d , P. Piattelli a , F. Raffaelli h , G. Raia a , N. Randazzo d , S. Reito d , G. Ricco e , G. Riccobene a , M. Ripani e , A ...

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2010

ANTARES is a high-energy neutrino telescope installed in the Mediterranean Sea at a depth of 2475... more ANTARES is a high-energy neutrino telescope installed in the Mediterranean Sea at a depth of 2475 m. It consists of a three-dimensional array of optical modules, each containing a large photomultiplier tube. A total of 2700 frontend ASICs named Analogue Ring Samplers (ARS) process the phototube signals, measure their arrival time, amplitude and shape as well as perform monitoring and calibration tasks. The ARS chip processes the analogue signals from the optical modules and converts information into digital data. All the information is transmitted to shore through further multiplexing electronics and an optical link. This paper describes the performance of the ARS chip; results from the functionality and characterization tests in the laboratory are summarized and the long-term performance in the apparatus is illustrated.

by G. Larosa, J. Brunner, V. Bertin, M. Bouwhuis, Christian Curtil, Giulia De Bonis, S. Escoffier, P. Keller, Annarita Margiotta, P. Kooijman, and Domenico Lo Presti

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2011

The AMADEUS (ANTARES Modules for the Acoustic Detection Under the Sea) system which is described ... more The AMADEUS (ANTARES Modules for the Acoustic Detection Under the Sea) system which is described in this article aims at the investigation of techniques for acoustic detection of neutrinos in the deep sea. It is integrated into the ANTARES neutrino telescope in the Mediterranean Sea. Its acoustic sensors, installed at water depths between 2050 and 2300 m, employ piezo-electric elements for the broad-band recording of signals with frequencies ranging up to 125 kHz. The typical sensitivity of the sensors is around −145 dB re 1V/µPa (including preamplifier). Completed in May 2008, AMADEUS consists of six "acoustic clusters", each comprising six acoustic sensors that are arranged at distances of roughly 1 m from each other. Two vertical mechanical structures (so-called lines) of the ANTARES detector host three acoustic clusters each. Spacings between the clusters range from 14.5 to 340 m. Each cluster contains custom-designed electronics boards to amplify and digitise the acoustic signals from the sensors. An on-shore computer cluster is used to process and filter the data stream and store the selected events. The daily volume of recorded data is about 10 GB. The system is operating continuously and automatically, requiring only little human intervention. AMADEUS allows for extensive studies of both transient signals and ambient noise in the deep sea, as well as signal correlations on several length scales and localisation of acoustic point sources. Thus the system is excellently suited to assess the background conditions for the measurement of the bipolar pulses expected to originate from neutrino interactions. 4 a local heating of the medium which is instantaneous with respect to the hydro-7 dynamic time scales. This temperature change induces an expansion or contrac-8 tion of the medium depending on its volume expansion coefficient. According to 9 the thermo-acoustic model 2], the accelerated motion of the heated volume-a 10 micro-explosion-forms a pressure pulse of bipolar shape which propagates in the 11 surrounding medium. Coherent superposition of the elementary sound waves, pro-12 duced over the volume of the energy deposition, leads to a propagation within a 13 flat disk-like volume (often referred to as pancake) in the direction perpendicular 14 to the axis of the particle cascade. After propagating several hundreds of metres 15 in sea water, the pulse has a characteristic frequency spectrum that is expected to 16 peak around 10 kHz [3][4][5]. Given the strongly anisotropic propagation pattern of the 17 sound waves, the details of the pressure pulse, namely its amplitude, asymmetry and 18 frequency spectrum, depend on the distance and angular position of the observer 19 with respect to the particle cascade induced by the neutrino interaction [3]. Besides 20 sea water, which is the medium under investigation in the case of the AMADEUS 21 (ANTARES Modules for the Acoustic Detection Under the Sea) project, ice [6] 22

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2009

The ANTARES neutrino telescope, located 40 km off the coast of Toulon in the Mediterranean Sea at... more The ANTARES neutrino telescope, located 40 km off the coast of Toulon in the Mediterranean Sea at a mooring depth of about 2475 m, consists of twelve detection lines equipped typically with 25 storeys. Every storey carries three optical modules that detect Cherenkov light induced by charged secondary particles (typically muons) coming from neutrino interactions. As these lines are flexible structures fixed to the sea bed and held taut by a buoy, sea currents cause the lines to move and the storeys to rotate. The knowledge of the position of the optical modules with a precision better than 10 cm is essential for a good reconstruction of particle tracks. In this paper the ANTARES positioning system is described. It consists of an acoustic positioning system, for distance triangulation, and a compass-tiltmeter system, for the measurement of the orientation and inclination of the storeys. Necessary corrections are discussed and the results of the detector alignment procedure are described.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2009

... C. D'Amato a , V. D&... more ... C. D'Amato a , V. D'Amato a , G. De Bonis q , G. De Rosa g , G. De Ruvo b , R. De Vita e , C. Distefano a , E. Falchini p , V. Flaminio p , K ... a , C. Petta m , P. Piattelli a , D. Piombo e , F. Raffaelli p , G. Raia a , N. Randazzo d , S. Reito d , G. Ricco n , G. Riccobene a , M. Ripani e , A ...

Astroparticle Physics, 2016

ABSTRACT The ANTARES experiment consists of an array of photomultipliers distributed along 12 lin... more 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\simsim10 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.

Journal of Cosmology and Astroparticle Physics, 2016

optical or X-ray counterparts associated to the neutrino triggers have been found, and upper limi... more 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.

Astronomy & Astrophysics, 2015

The source(s) of the neutrino excess reported by the IceCube Collaboration is unknown. The TANAMI... more 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

Ocean Science Discussions, 2010

... K. Fratini 24,3 , U. Fritsch 4 , J.-L. Fuda 22 , G. Giacomelli 11,12 , JP G ómez-González 1 ,... more ... K. Fratini 24,3 , U. Fritsch 4 , J.-L. Fuda 22 , G. Giacomelli 11,12 , JP G ómez-González 1 , ... van Amsterdam, Institut voor Hoge-Energiefysika, Science Park 105, 1098 XG Amsterdam, The Netherlands 30Dipartimento di Fisica ed Astronomia dell'Universit`a, Viale Andrea Doria 6 ...

A 13-inch Optical Module (OM) containing a large-area (10-inch) photomultiplier was designed as p... more A 13-inch Optical Module (OM) containing a large-area (10-inch) photomultiplier was designed as part of Phase-2 of the NEMO project. An intense R&D activity on the photomultipliers, the voltage supply boards, the optical coupling as well as the study of the influences of the Earth's magnetic field has driven the choice of each single component of the OM. Following a well-established production procedure, 32 OMs were assembled and their functionality tested. The design, the testing and the production phases are thoroughly described in this paper.

In the underwater neutrino telescopes, the positions of the Cherenkov light sensors and their mov... more In the underwater neutrino telescopes, the positions of the Cherenkov light sensors and their movements must be known with an accuracy of few tens of centimetres. In this work, the activities of the SMO and KM3NeT-Italia teams for the development of an acoustic positioning system for KM3NeT-Italia project are presented. The KM3NeT-Italia project foresees the construction, within two years, of 8 towers in the view of the several km 3 -scale neutrino telescope KM3NeT.

Journal of High Energy Astrophysics, 2014

The first prototype of a photo-detection unit of the future KM3NeT neutrino telescope has been de... more 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 localisation bioluminescent activity in the neighbourhood. The single unit can cleanly identify atmospheric muons and provide sensitivity to the muon arrival directions.

Context. The jets of radio-loud Active Galactic Nuclei are among the most powerful particle accel... more 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 × 10 46 erg 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.

IEEE Nuclear Science Symposium Conference Record, 2007

... A. D'Amico d, G. De Bonis j, C. De Marzo a, G. De Rosa n, G. De Ruvo a, R. De Vita e, C.... more ... A. D'Amico d, G. De Bonis j, C. De Marzo a, G. De Rosa n, G. De Ruvo a, R. De Vita e, C. Distefano d, E. Falchini f, V. Flaminio f, K ... V. Pappalardo d, C. Petta p, P. Piattelli d, D. Piombo e, F. Raffaelli f, G. Raia d, N. Randazzo b, S. Reito b, G. Ricco i, G. Riccobene d, M. Ripani e, A ...

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2011

The ANTARES Neutrino Telescope was completed in May 2008 and is the first operational Neutrino Te... more 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.

The Astrophysical Journal, 2012

In this paper, a time integrated search for point sources of cosmic neutrinos is presented using ... more In this paper, a time integrated search for point sources of cosmic neutrinos is presented using the data collected from 2007 to 2010 by the ANTARES neutrino telescope. No statistically significant signal has been found and upper limits on the neutrino flux have been obtained. Assuming an E −2 ν spectrum, these flux limits are at 1 − 10×10 −8 GeV cm −2 s −1 for declinations ranging from −90 • to The Netherlands -4 -40 • . Limits for specific models of RX J1713.7-3946 and Vela X, which include information on the source morphology and spectrum, are also given.

The Astrophysical Journal, 2013

This paper presents a search for correlation in the arrival directions of 2190 neutrino candidate... more This paper presents a search for correlation in the arrival directions of 2190 neutrino candidate events detected in 2007-2008 by the ANTARES telescope, and 69 ultra-high energy cosmic rays (UHECRs) observed by the Pierre Auger Observatory between January 1st 2004 and December 31st 2009. No significant correlation was found. The corresponding 90% C.L. upper limit on the neutrino flux from each observed UHECR direction (assuming an equal flux from all of them and for E −2 energy spectrum) is 4.99×10 −8 GeVcm −2 s −1 .

Physical Review Letters, 2013

Nuclear Physics B - Proceedings Supplements, 2007

... G. De Bonis i , C. De Marzo b , maltese cross , G. De Rosa g , R. De Vita e , C. Distefano a ... more ... G. De Bonis i , C. De Marzo b , maltese cross , G. De Rosa g , R. De Vita e , C. Distefano a , E. Falchini h , C. Fiorello b , V. Flaminio h , K ... V. Pappalardo a , C. Petta d , P. Piattelli a , F. Raffaelli h , G. Raia a , N. Randazzo d , S. Reito d , G. Ricco e , G. Riccobene a , M. Ripani e , A ...

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2010

ANTARES is a high-energy neutrino telescope installed in the Mediterranean Sea at a depth of 2475... more ANTARES is a high-energy neutrino telescope installed in the Mediterranean Sea at a depth of 2475 m. It consists of a three-dimensional array of optical modules, each containing a large photomultiplier tube. A total of 2700 frontend ASICs named Analogue Ring Samplers (ARS) process the phototube signals, measure their arrival time, amplitude and shape as well as perform monitoring and calibration tasks. The ARS chip processes the analogue signals from the optical modules and converts information into digital data. All the information is transmitted to shore through further multiplexing electronics and an optical link. This paper describes the performance of the ARS chip; results from the functionality and characterization tests in the laboratory are summarized and the long-term performance in the apparatus is illustrated.

by G. Larosa, J. Brunner, V. Bertin, M. Bouwhuis, Christian Curtil, Giulia De Bonis, S. Escoffier, P. Keller, Annarita Margiotta, P. Kooijman, and Domenico Lo Presti

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2011

The AMADEUS (ANTARES Modules for the Acoustic Detection Under the Sea) system which is described ... more The AMADEUS (ANTARES Modules for the Acoustic Detection Under the Sea) system which is described in this article aims at the investigation of techniques for acoustic detection of neutrinos in the deep sea. It is integrated into the ANTARES neutrino telescope in the Mediterranean Sea. Its acoustic sensors, installed at water depths between 2050 and 2300 m, employ piezo-electric elements for the broad-band recording of signals with frequencies ranging up to 125 kHz. The typical sensitivity of the sensors is around −145 dB re 1V/µPa (including preamplifier). Completed in May 2008, AMADEUS consists of six "acoustic clusters", each comprising six acoustic sensors that are arranged at distances of roughly 1 m from each other. Two vertical mechanical structures (so-called lines) of the ANTARES detector host three acoustic clusters each. Spacings between the clusters range from 14.5 to 340 m. Each cluster contains custom-designed electronics boards to amplify and digitise the acoustic signals from the sensors. An on-shore computer cluster is used to process and filter the data stream and store the selected events. The daily volume of recorded data is about 10 GB. The system is operating continuously and automatically, requiring only little human intervention. AMADEUS allows for extensive studies of both transient signals and ambient noise in the deep sea, as well as signal correlations on several length scales and localisation of acoustic point sources. Thus the system is excellently suited to assess the background conditions for the measurement of the bipolar pulses expected to originate from neutrino interactions. 4 a local heating of the medium which is instantaneous with respect to the hydro-7 dynamic time scales. This temperature change induces an expansion or contrac-8 tion of the medium depending on its volume expansion coefficient. According to 9 the thermo-acoustic model 2], the accelerated motion of the heated volume-a 10 micro-explosion-forms a pressure pulse of bipolar shape which propagates in the 11 surrounding medium. Coherent superposition of the elementary sound waves, pro-12 duced over the volume of the energy deposition, leads to a propagation within a 13 flat disk-like volume (often referred to as pancake) in the direction perpendicular 14 to the axis of the particle cascade. After propagating several hundreds of metres 15 in sea water, the pulse has a characteristic frequency spectrum that is expected to 16 peak around 10 kHz [3][4][5]. Given the strongly anisotropic propagation pattern of the 17 sound waves, the details of the pressure pulse, namely its amplitude, asymmetry and 18 frequency spectrum, depend on the distance and angular position of the observer 19 with respect to the particle cascade induced by the neutrino interaction [3]. Besides 20 sea water, which is the medium under investigation in the case of the AMADEUS 21 (ANTARES Modules for the Acoustic Detection Under the Sea) project, ice [6] 22

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2009

The ANTARES neutrino telescope, located 40 km off the coast of Toulon in the Mediterranean Sea at... more The ANTARES neutrino telescope, located 40 km off the coast of Toulon in the Mediterranean Sea at a mooring depth of about 2475 m, consists of twelve detection lines equipped typically with 25 storeys. Every storey carries three optical modules that detect Cherenkov light induced by charged secondary particles (typically muons) coming from neutrino interactions. As these lines are flexible structures fixed to the sea bed and held taut by a buoy, sea currents cause the lines to move and the storeys to rotate. The knowledge of the position of the optical modules with a precision better than 10 cm is essential for a good reconstruction of particle tracks. In this paper the ANTARES positioning system is described. It consists of an acoustic positioning system, for distance triangulation, and a compass-tiltmeter system, for the measurement of the orientation and inclination of the storeys. Necessary corrections are discussed and the results of the detector alignment procedure are described.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2009

... C. D'Amato a , V. D&... more ... C. D'Amato a , V. D'Amato a , G. De Bonis q , G. De Rosa g , G. De Ruvo b , R. De Vita e , C. Distefano a , E. Falchini p , V. Flaminio p , K ... a , C. Petta m , P. Piattelli a , D. Piombo e , F. Raffaelli p , G. Raia a , N. Randazzo d , S. Reito d , G. Ricco n , G. Riccobene a , M. Ripani e , A ...