A recent analysis of the Fermi Large Area Telescope data provided evidence for a high-intensity emission of high-energy gamma rays with a E−2 spectrum from two large areas, spanning 50° above and below the Galactic centre (the “Fermi bubbles”). A hadronic mechanism was proposed for this gamma-ray emission making the Fermi bubbles promising source candidates of high-energy neutrino emission. In this work Monte Carlo simulations regarding the detectability of high-energy neutrinos from the Fermi bubbles with the future multi-km3 neutrino telescope KM3NeT in the Mediterranean Sea are presented. Under the hypothesis that the gamma-ray emission is completely due to hadronic processes, the results indicate that neutrinos from the bubbles could be discovered in about one year of operation, for a neutrino spectrum with a cutoff at 100TeV and a detector with about 6km3 of instrumented volume. The effect of a possible lower cutoff is also considered.
Detection of high-energy neutrinos from distant astrophysical sources will open a new window on the Universe. The detection principle exploits the measurement of Cherenkov light emitted by charged particles resulting from neutrino interactions in the matter containing the telescope. A novel multi-PMT digital optical module (DOM) was developed to contain 31 3-inch photomultiplier tubes (PMTs). In order to maximize the detector sensitivity, each PMT will be surrounded by an expansion cone which collects photons that would otherwise miss the photocathode. Results for various angles of incidence with respect to the PMT surface indicate an increase in collection efficiency by 30% on average for angles up to 45° with respect to the perpendicular. Ray-tracing calculations could reproduce the measurements, allowing to estimate an increase in the overall photocathode sensitivity, integrated over all angles of incidence, by 27% (for a single PMT). Prototype DOMs, being built by the KM3NeT consortium, will be equipped with these expansion cones.
Historically, observation in Marine Science was mainly based on in situ measurements made mainly over ship surveys and shore measurements. Unfortunately, ship surveys can only be episodic, and are constrained by weather and by the constant rise of ship-time cost. As the data provided by non-communicating moorings are stored in the measurement system, a ship intervention is needed to recover both the mooring and the data after several acquisition months. Further to the rather successful mediumand short-term deployment of these traditional devices, scientists have expected the development of long-term observations and permanent marine system-monitoring tools so as to gain more insight into the observed processes. By providing additional information, satellite technology can partly solve this gap between the reality and expectations. However, even though satellite images provide information over a large time frame (from minutes to years) and a wide range of spatial resolutions (from metres to thousands of kilometres), they only cover the upper layer of the sea. An Open-Sea Observatory is a complementary tool that allows one to make, in the water column and on the seafloor, long-term measurements of many environmental parameters and to acquire them in real-time, or near real-time. In addition to this real-time data transmission, these systems permit remote intervention by humans when needed, and thus can be considered as 2-way communicating devices. Because of these two characteristics, observatories are innovative systems that bring internet to the ocean and make the ocean reality visible to the human eye. According to our definition of an Open-Sea observatory, other very useful observation tools such as gliders, floats, repeated profiler transects, etc. will not be considered in this chapter to only focus on such ocean observatories. Observatory initiatives have been spreading worldwide since the 1990s. In Europe, several initiatives started twenty years ago so as to upgrade free-fall systems from the sea surface (the so-called “landers”) to make them 2-way communicating and to develop bottom
Recently the ANTARES Neutrino telescope's Infrastructure in the deep Mediterranean Sea, has been extended by a Secondary Junction Box. The main emphasis has been to provide basic power and communications capability for new scientific cabled observatories. This new infrastructure provides unprecedented amounts of power and two-way bandwidth to access and control instrument networks in the oceans. This new development allows cabled observatory to connect the seafloor to the Internet via real-time, two-way highspeed communications. This design gives researchers new capabilities beyond the reach of traditional oceanography. Ocean scientists can run deep-water experiments from labs and universities anywhere around the world. Three different underwater observatories are already been connected at this Secondary Junction Box. This paper presents this new Infrastructure which has been deployed by the R/V Pourquoi Pas? and connected by the IFREMER's ROV VICTOR6000. After a technical description of the system, we detailled an overview of the complete deployment at sea.
ABSTRACT A method for the prompt and cost-effective intervention and remediation of tanker wrecks dealing with eventual leaks and recovering the fuel trapped in their tanks, even at considerable depths, is described. The method is of general applicability as long as the trapped pollutant does not dissolve and is of lower density than sea water. It relies on gravity to channel the flow of spilt fuel towards the surface. Instead of channeling the flow directly to the surface, the fuel-water mix is directed to a buffer reservoir/separator some 30–50 m below the sea surface so as not to be affected by rough weather. This is achieved by means of a light, quickly deployable flexible structure that should stay in place until all the tanks of the wreck are emptied and the pollution threat eliminated. The buffer reservoir, into which the spilt fuel is channelled, is provided with standard equipment through which shuttle vessels, weather permitting, can recover the fuel rapidly, using standard off-shore equipment and procedures.
EXOCET/D was a three-year project that started in 2004 and that was funded by the European Commission (STREP, FP6-GOCE-CT-2003-505342). The general objective of this project was to develop, implement and test specific technologies aimed at exploring, describing and quantifying biodiversity in deep-sea fragmented habitats as well as at identifying links between community structure and environmental dynamics. The MoMARETO cruise, held during the summer 2006, was the main demonstration action of EXOCET/D. After nearly 3 years of development, the project was a real success with the at sea trial and validation of 13 instrument prototypes developed for the study of deep-sea extreme habitats. These instruments were dedicated to quantitative imaging, in situ measurements, faunal sampling and in vivo experiments.
ANTARES is a neutrino telescope being deployed in the Mediterranean Sea. It consists of a three dimensional array of photomultiplier tubes that can detect the Cherenkov light induced by charged particles produced in the interactions of neutrinos with the surrounding medium. High angular resolution can be achieved, in particular when a muon is produced, provided that the Cherenkov photons are detected with sufficient timing precision. Considerations of the intrinsic time uncertainties stemming from the transit time spread in the photomultiplier tubes and the mechanism of transmission of light in sea water lead to the conclusion that a relative time accuracy of the order of 0.5 ns is desirable. Accordingly, different time calibration systems have been developed for the ANTARES telescope. In this article, a system based on Optical Beacons, a set of external and well-controlled pulsed light sources located throughout the detector, is described. This calibration system takes into account the optical properties of sea water, which is used as the detection volume of the ANTARES telescope. The design, tests, construction and first results of the two types of beacons, LED and laser-based, are presented.
A full-scale mechanical prototype line was deployed to a depth of 2500m to test the leak tightness of the electronics containers and the pressure-resistant properties of an electromechanical cable under evaluation for use in the ANTARES deep-sea neutrino telescope. During a month-long immersion study, line parameter data were taken using miniature autonomous data loggers and shore-based optical time domain reflectometry. Details of the mechanical prototype line, the electromechanical cable and data acquisition are presented. Data taken during the immersion study revealed deficiencies in the pressure resistance of the electromechanical cable terminations at the entry points to the electronics containers. The improvements to the termination, which have been integrated into subsequent detection lines, are discussed. The line also allowed deep-sea acoustic measurements with a prototype hydrophone system. The technical setup of this system is described, and the first results of the data analysis are presented.
In 2005, the ANTARES Collaboration deployed and operated at a depth of 2500 m a so-called Mini Instrumentation Line equipped with Optical Modules (MILOM) at the ANTARES site. The various data acquired during the continuous operation from April to December 2005 of the MILOM confirm the satisfactory performance of the Optical Modules, their front-end electronics and readout system. as well as the calibration devices of the detector. The in situ measurement of the Optical Module time response yields a resolution better than 0.5 ns. The performance of the acoustic positioning system, which enables the spatial reconstruction of the ANTARES detector with a precision of about 10 cm, is verified. These results demonstrate that with the full ANTARES neutrino telescope the design angular resolution of better than 0.3 degrees can be realistically achieved. Crown Copyright (c) 2006 Published by Elsevier B.V. All rights reserved.
The ANTARES neutrino telescope, to be immersed depth in the Mediterranean Sea, will consist of a three-dimensional matrix of 900 large area photomultiplier tubes housed in pressure-resistant glass spheres. The selection of the optimal photomultiplier was a critical step for the project and required an intensive phase of tests and developments carried out in close collaboration with the main manufacturers worldwide. This paper provides an overview of the tests performed by the collaboration and describes in detail the features of the photomultiplier tube chosen for ANTARES.
The general objective of EXOCET/D is to develop, implement and test specific instruments aimed at exploring, describing, quantifying and monitoring biodiversity in deep-sea fragmented habitats as well as at identifying links between community structure and environmental dynamics. Inboard experimental devices will complement the approach, enabling experiments on species physiology. The EXOCET/D working fields include: video and acoustic imagery, in situ analysis of physico- chemical factors, quantitative sampling of macro- and micro- organisms, in vivo experiments, integration of multidisciplinary data, implementation on European deep-submersibles and a final phase of technical and scientific validation.
Following the needs of a widening community of end users the modular deep Remotely Operated Vehicle Victor 6000 of the Institut Francais d’Exploitation de la Mer, Ifremer, is evolving using new technologies. A deep record dive at high latitude (79°north) was reached in the Molloy Deep at 5550 metres in 1999. The performance obtained till 2002 during 2600 hours of work/survey near the seafloor are contributing significantly to the observation and the monitoring of the deep benthic ecosystems in various environments of the midoceanic ridges and the continental margins.
The evaluation of the first year of intensive scientific use of the French deep sea remotely operated vehicle (ROV) "Victor 6000" is presented. Victor was used in 2001 during five cruises on the continental margins. The Zairov 1 & 2, Biozaire 1 & 2 cruises were conducted offshore Western Africa and the Caracole cruise was conducted along the North East Atlantic margins (Porcupine and Rockall bank). Cold seep settings (up to 3000 m depth), coral mounds (400-1000 m), oil exploration rigs (1300 m) and the Zaire channel (about 4000 m) were explored. Victor carried out on site work during two cruises (IRIS & ATOS) on the hydrothermal vent areas in the Mid Atlantic Ridge (Menez Gwen 850 m, Lucky Strike 1650 m and Rainbow 2350 m). Finally, Victor was used by the Alfred Wegener Institute, through a French-German cooperation in the Arctic deep sea, to study the high diversity of species in the deep sea, at high latitude (AWI leg). Different strategies were tested during those cruises like survey and exploration or experimental work on small areas. The dive durations ranged between 8 to 28 hours on the bottom. The high potential of Victor was confirmed in both strategies with a high ability for the manipulation and. the trials of varied pieces of instrumentation. The status and recent evolution of Victor 6000 are presented showing the essential role of dynamic technical support oriented toward scientific objectives and operability.
The ANTARES collaboration has performed a series of {\em in situ} measurements to study the background light for a planned undersea neutrino telescope. Such background can be caused by $^{40}$K decays or by biological activity. We report on measurements at two sites in the Mediterranean Sea at depths of 2400~m and 2700~m, respectively. Three photomultiplier tubes were used to measure single counting rates and coincidence rates for pairs of tubes at various distances. The background rate is seen to consist of three components: a constant rate due to $^{40}$K decays, a continuum rate that varies on a time scale of several hours simultaneously over distances up to at least 40~m, and random bursts a few seconds long that are only correlated in time over distances of the order of a meter. A trigger requiring coincidences between nearby photomultiplier tubes should reduce the trigger rate for a neutrino telescope to a manageable level with only a small loss in efficiency.
The ANTARES Collaboration proposes to construct a large area water Cherenkov detector in the deep Mediterranean Sea, optimised for the detection of muons from high-energy astrophysical neutrinos. This paper presents the scientific motivation for building such a device, along with a review of the technical issues involved in its design and construction. The observation of high energy neutrinos will open a new window on the universe. The primary aim is to study particle acceleration mechanisms in energetic astrophysical objects such as AGN's and GRB's, which may also shed light on the origin of ultra-high-energy cosmic rays. At lower energies, non-baryonic dark matter may be detected through the neutrinos produced when gravitationally captured WIMPs annihilate in the cores of the Earth and the Sun. Neutrino oscillations can be measured by studying distortions in the energy spectrum of upward-going atmospheric nu's. The characteristics of the proposed site are an important consideration in detector design. Water properties and detector environment parameters were measured. These tests have shown that the proposed site provides a good-quality environment for the detector, and have also demonstrated the feasibility of the deployment technique. The present proposal concerns the construction and deployment of a detector with surface area 0.1 km^2. The conceptual design for such a detector is discussed, and the physics performance evaluated. An overview of costs and schedules is presented. It is concluded that a 0.1 km^2 detector is technically feasible at realistic cost, and offers an exciting and varied physics and astrophysics programme. Such a detector will also provide practical experience which will be invaluable in the design and operation of future detectors on the astrophysically desirable 1 km^2 scale.