The use of conventional neutrino telescope methods and technology for detecting neutrinos with energies above 1 EeV from astrophysical sources would be prohibitively expensive and may turn out to be technically not feasible. Acoustic detection is a promising alternative for future deep-sea neutrino telescopes operating in this energy regime. It utilises the effect that the energy deposit of the particle cascade evolving from a neutrino interaction in water generates a coherently emitted sound wave with frequency components in the range between about 1 and 50 kHz. The AMADEUS (Antares Modules for Acoustic DEtection Under the Sea) project is integrated into the ANTARES neutrino telescope and aims at the investigation of techniques for acoustic particle detection in sea water. The acoustic sensors of AMADEUS are using piezo elements and are recording a broad-band signal with frequencies ranging up to 125 kHz. After an introduction to acoustic neutrino detection it will be shown how an acoustic array similar to AMADEUS can be used for positioning as well as acoustic particle detection. Experience from AMADEUS and possibilities for a future large scale neutrino telescope in the Mediterranean Sea will be discussed.
This article focuses on techniques for position reconstruction of acoustic point sources with the AMADEUS setup consisting of 36 acoustic sensors in the Mediterranean Sea. The direction reconstruction of an acoustic point source utilizes the information of the 6 small-volume hydrophone clusters of AMADEUS individually. Source position reconstruction is then done by combining the directional information of each cluster. The algorithms for direction and position reconstruction are explained and demonstrated using data taken in the deep sea.
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-…
The AMADEUS system is integrated in the ANTARES neutrino telescope in the Mediterranean Sea and aims for the investigation of acoustic particle detection techniques in the deep sea. Installed at a depth of more than 2000m, the acoustic sensors of AMADEUS are using piezo-ceramic elements for the broad-band recording of acoustic signals with frequencies ranging up to 125kHz. AMADEUS consists of six clusters, each one comprising six acoustic sensors that are arranged at distances of roughly 1m from each other. Three acoustic clusters are installed along a vertical mechanical structure (a so-calle…
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/muPa (including preamplifier). Completed in May 2008, AMADEUS consis…
The emission of neutrinos within a wide energy range is predicted from very-high-energy phenomena in the Universe. Even the current or next-generation Cherenkov neutrino telescopes might be too small to detect the faint fluxes expected for cosmic neutrinos with energies exceeding the EeV scale. The acoustic detection method is a promising option to enlarge the discovery potential in this highest-energy regime. In a possible future deep-sea detector, the pressure waves produced in a neutrino interaction could be detected by a 100 km\^3-sized array of acoustic sensors, even if it is sparsely ins…
The ANTARES Neutrino Telescope is a water Cherenkov detector composed of an array of approximately 900 photomultiplier tubes in 12 vertical strings, spread over an area of about 0.1 km^2 with an instrumented height of about 350 metres. ANTARES, built in the Mediterranean Sea, is the biggest neutrino Telescope operating in the northern hemisphere. Acoustic sensors (AMADEUS project) have been integrated into the infrastructure of ANTARES, grouped in small arrays, to evaluate the feasibility of a future acoustic neutrino telescope in the deep sea operating in the ultra-high energy regime. In this…
Acousticneutrinodetectionisapromisingapproachforlarge-scaleultra-highenergyneutrinodetectorsinwater.In this article, a Monte Carlo simulation chain for acoustic neutrino detection devices in water will be presented. The simulation chain covers the generation of the acoustic pulse produced by a neutrino interaction and its propagation to the sensors within the detector. Currently, ambient and transient noise models for the Mediterranean Sea and simulations of the data acquisition hardware, equivalent to the one used in ANTARES/AMADEUS, are implemented. A pre-selection scheme for neutrino-like s…
Acoustic neutrino detection is a promising approach for large-scale ultra-high energy neutrino detectors in water. In this article, a Monte Carlo simulation chain for acoustic neutrino detection devices in water is presented. It is designed within the SeaTray/IceTray software framework. Its modular architecture is highly flexible and makes it easy to adapt to different environmental conditions, detector geometries, and hardware. The simulation chain covers the generation of the acoustic pulse produced by a neutrino interaction and the propagation to the sensors within the detector. In this pha…
Acoustic neutrino detection is a promising approach to extend the energy range of neutrino telescopes to energies beyond $10^{18}$\,eV. Currently operational and planned water-Cherenkov neutrino telescopes, most notably KM3NeT, include acoustic sensors in addition to the optical ones. These acoustic sensors could be used as instruments for acoustic detection, while their main purpose is the position calibration of the detection units. In this article, a Monte Carlo simulation chain for acoustic detectors will be presented, covering the initial interaction of the neutrino up to the signal class…
This article focuses on techniques for acoustic noise reduction, signal filters and source reconstruction. For noise reduction, bandpass filters and cross correlations are found to be efficient and fast ways to improve the signal to noise ratio and identify a possible neutrino-induced acoustic signal. The reconstruction of the position of an acoustic point source in the sea is performed by using small-volume clusters of hydrophones (about 1 cubic meter) for direction reconstruction by a beamforming algorithm. The directional information from a number of such clusters allows for position recons…
The acoustic neutrino detection technique is a promising approach for future large-scale detectors with the aim of measuring the small expected flux of neutrinos at energies in the EeV-range and above. The technique is based on the thermo-acoustic model, which implies that the energy deposition by a particle cascade - resulting from a neutrino interaction in a medium with suitable thermal and acoustic properties - leads to a local heating and a subsequent characteristic pressure pulse that propagates in the surrounding medium. Current or recent test setups for acoustic neutrino detection have …
Arrays of acoustic receivers are an integral part of present and potential future Cherenkov neutrino telescopes in the deep sea. They measure the positions of individual detector elements which vary with time as an effect of undersea currents. At the same time, the acoustic receivers can be employed for marine science purposes, in particular for monitoring the ambient noise environment and the signals emitted by the fauna of the sea. And last but not least, they can be used for studies towards acoustic detection of ultra-high-energy neutrinos. Measuring acoustic pressure pulses in huge underwa…
We report theoretical and experimental results of on-going feasibility studies to detect cosmic neutrinos acoustically in Lake Baikal. In order to examine ambient noise conditions and to develop respective pulse detection techniques a prototype device was created. The device is operating at a depth of 150 m at the site of the Baikal Neutrino Telescope and is capable to detect and classify acoustic signals with different shapes, as well as signals from neutrino-induced showers.
KM3NeT is a future multi-cubic-kilometre water Cherenkov neutrino telescope currently entering a first construction phase. It will be located in the Mediterranean Sea and comprise about 600 vertical structures called detection units. Each of these detection units has a length of several hundred metres and is anchored to the sea bed on one side and held taut by a buoy on the other side. The detection units are thus subject to permanent movement due to sea currents. Modules holding photosensors and additional equipment are equally distributed along the detection units. The relative positions of …
The proposed large scale Cherenkov neutrino telescope KM3NeT will carry photo-sensors on flexible structures, the detection units. The Mediterranean Sea, where KM3NeT will be installed, constitutes a highly dynamic environment in which the detection units are constantly in motion. Thus it is necessary to monitor the exact sensor positions continuously to achieve the desired resolution for the neutrino telescope. A common way to perform this monitoring is the use of acoustic positioning systems with emitters and receivers based on the piezoelectric effect. The acoustic receivers are attached to…
Friedrich-Alexander-Universität Erlangen-Nürnberg（埃尔朗根-纽伦堡弗里德里希-亚历山大大学）；Erlangen Centre for Astroparticle Physics（埃尔朗根天体粒子物理中心）
This article focuses on signal classification for deep-sea acoustic neutrino detection. In the deep sea, the background of transient signals is very diverse. Approaches like matched filtering are not sufficient to distinguish between neutrino-like signals and other transient signals with similar signature, which are forming the acoustic background for neutrino detection in the deep-sea environment. A classification system based on machine learning algorithms is analysed with the goal to find a robust and effective way to perform this task. For a well-trained model, a testing error on the level…
The next generation multi-cubic-kilometre water Cherenkov neutrino telescope will be build in the Mediterranean Sea. This telescope, called KM3NeT, is currently entering a first construction phase. The KM3NeT research infrastructure will comprise 690 so-called Detection Units in its final design which will be anchored to the sea bed and held upright by submerged floats. The positions of these Detection Units, several hundred metres in length, and their attached Optical Modules for the detection of Cherenkov light have to be monitored continously to provide the telescope with its desired pointi…
We describe the sound emission board proposed for installation in the acoustic positioning system of the future KM3NeT underwater neutrino telescope. The KM3NeT European consortium aims to build a multi-cubic kilometre underwater neutrino telescope in the deep Mediterranean Sea. In this kind of telescope the mechanical structures holding the optical sensors, which detect the Cherenkov radiation produced by muons emanating from neutrino interactions, are not completely rigid and can move up to dozens of meters in undersea currents. Knowledge of the position of the optical sensors to an accuracy…
With the aim to optimize and test the method of acoustic detection of ultra-high energy neutrinos in underwater telescopes a compact acoustic transmitter array has been developed. The acoustic parametric effect is used to reproduce the acoustic signature of an ultra-high-energy neutrino interaction. Different reseach and development studies are presented in order to show the viability of the parametric sources technique to deal with the difficulties of the acoustic signal generation: a very directive transient bipolar signal with pancake directivity. The design, construction and characterizati…
The production of acoustic signals from the interactions of ultra-high energy (UHE) cosmic ray neutrinos in water and ice has been studied. A new computationally fast and efficient method of deriving the signal is presented. This method allows the implementation of up to date parameterisations of acoustic attenuation in sea water and ice that now includes the effects of complex attenuation, where appropriate. The methods presented here have been used to compute and study the properties of the acoustic signals which would be expected from such interactions. A matrix method of parameterising the…
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…
In this paper acoustic transmitters that were developed for use in underwater neutrino telescopes are presented. Firstly, an acoustic transceiver has been developed as part of the acoustic positioning system of neutrino telescopes. These infrastructures are not completely rigid and require a positioning system in order to monitor the position of the optical sensors which move due to sea currents. To guarantee a reliable and versatile system, the transceiver has the requirements of reduced cost, low power consumption, high pressure withstanding (up to 500 bars), high intensity for emission, low…
The study and application of signal detection techniques based on cross-correlation method for acoustic transient signals in noisy and reverberant environments are presented. These techniques are shown to provide high signal to noise ratio, good signal discernment from very close echoes and accurate detection of signal arrival time. The proposed methodology has been tested on real data collected in environments and conditions where its benefits can be shown. This work focuses on the acoustic detection applied to tasks of positioning in underwater structures and calibration such those as ANTARE…
In this paper, we present the acoustic transceiver developed for the positioning system in underwater neutrino telescopes. These infrastructures are not completely rigid and need a positioning system in order to monitor the position of the optical sensors of the telescope which have some degree of motion due to sea currents. To have a highly reliable and versatile system in the infrastructure, the transceiver has the requirements of reduced cost, low power consumption, high intensity for emission, low intrinsic noise, arbitrary signals for emission and the capacity of acquiring and processing …
A possible detection of ultra-high-energy neutrinos has been attempted since decades through the Askarian radiation and different observation techniques. In fact, when such energetic neutrinos interact in a medium are able to produce a thermo-acoustic effect resulting in a bipolar pressure pulse that carries a portion of the energy generated by the particle cascades. This effect can be observed in atmosphere looking for the correlated radio emission and in ice/water searching directly the acoustic pulse. The kilometric attenuation length as well as the well-defined shape of the expected pulse …
Calibration of acoustic neutrino telescopes with neutrino-like signals is an essential aspect to evaluate the feasibility of the technique and to know the efficiency of the detectors. However, it is not straightforward to have acoustic transmitters that, on one hand, are able to mimic the signature of a UHE neutrino interaction, that is, a bipolar acoustic pulse with the 'pancake' directivity, and, on the other hand, fulfill practical issues such as ease of deployment and operation. This is a non-trivial problem since it requires directive transducer with cylindrical symmetry for a broadband f…
Ultra high energy neutrinos may be observed in ice by the emission of acoustic signals. The SPATS detector has investigated the possibility of observing GZK-neutrinos in the clear ice near the South Pole at the IceCube detector site. To explore other potential detection sites glacial ice in the Alps and in Antarctica has been surveyed for its acoustical properties. The purpose of the Enceladus Explorer (EnEx), on the other hand, is the search for extraterrestrial life on the Saturn moon Enceladus. Here acoustics is used to maneuver a subsurface probe inside the ice by trilateration of signals.…
The existence of cosmic accelerators able to emit charged particles up to EeV energies has been confirmed by the observations made in the last years by experiments such as Auger and Telescope Array. The interaction of such energetic cosmic-rays with gas or low energy photons, surrounding the astrophysical sources or present in the intergalactic medium, guarantee an ultra-high-energy neutrino related emission. When these energetic neutrinos interact in a medium produce a thermo-acoustic process where the energy of generated particle cascades can be conveyed in a pressure pulse propagating into …
