ANTARES (telescope)
Encyclopedia
ANTARES is the name of a neutrino detector
residing 2.5 km under the Mediterranean Sea
off the coast of Toulon
, France
. It is designed to be used as a directional Neutrino Telescope to locate and observe neutrino
flux
from cosmic origins in the direction of the Southern Hemisphere
of the Earth
, a complement to the northern hemisphere neutrino detector IceCube. The name comes from Astronomy with a Neutrino Telescope and Abyss environmental RESearch project; the acronym also being the name of the prominent star Antares
. Other neutrino telescopes designed for use in the nearby area include the Greek
NESTOR
telescope and the Italian
NEMO telescope, which are both in early design stages.
tubes. Each one has 75 optical modules and is about 350 meters long. They are anchored at the bottom of the sea at a depth of about 2.5 km, roughly 70 meters apart from each other. When neutrinos enter the southern hemisphere of the earth, they usually continue traveling directly through it. On rare occasions, a few muon
neutrinos interact with the water in the Mediterranean Sea. When this happens, they produce a high energy muon. ANTARES works by its photomultiplier tubes detecting the Cherenkov radiation
emitted as the muon passes through the water. The detection techniques used discriminate between the signature of "upward-going muons", a muon neutrino that has had interactions with matter below the detector (the Earth
), and much higher flux of "downward atmospheric muons".
In contrast to the South Pole
neutrino telescopes AMANDA
and IceCube, ANTARES uses water instead of ice as its Cherenkov medium. As light in water is less scattered than in ice this results in a better resolving power
. On the other hand, water contains more sources of background light than ice (radioactive isotopes potassium
-40 in the sea salt and bioluminescent organisms
), leading to a higher energy thresholds for ANTARES with respect to IceCube and making more sophisticated background-suppression methods necessary.
Initial testing began in 2000. Equipment indirectly related to the detector such as a seismometer
were deployed in 2005. The first string of photomultiplier tubes was moved into place in February 2006. In September 2006 the second line was successfully connected. Lines 3, 4 and 5 were deployed at the end of 2006 and connected in January 2007. This was an important step that made Antares the biggest neutrino telescope in the Northern hemisphere (surpassing the Baikal neutrino telescope). Lines 6, 7, 8, 9, and 10 were deployed between March and early November 2007 and connected in December 2007 and January 2008. From May 2008 the detector has been running in its complete 12-line configuration.
Deployment and connection of the detector are performed in cooperation with the French oceanographic institute, IFREMER
, currently using the ROV Victor, and for some past operations the submarine
Nautile
.
. The detection principles of the two projects are very similar, but they point toward opposite hemispheres. ANTARES will detect neutrinos from high energy origin, particularly in the range from
to 
electron-volts (100 GeV
- 100 TeV
). Over several years of operation, it may be able to produce a map of the neutrino flux
from cosmic origins in the southern hemisphere. Of particular interest is the detection of astrophysical point sources of neutrinos, possibly in correlation with observations in other bands (such as gamma rays sources observed by the HESS
telescope in Namibia
, which has a common field of view with ANTARES).
Apart from this astro-particle physics aspect, the ANTARES telescope will also tackle some fundamental problems in particle physics, such as the search for dark matter
in the form of neutralino
annihilation
in the sun
("normal" solar neutrinos being outside the energy range of ANTARES) or the galactic centre. Due to the very different methods employed, its expected sensitivity is nearly complementary to the direct dark matter searches performed by various experiments such as DAMA
, CDMS
and at the LHC
. Detection of neutralino signals would also confirm supersymmetry
. Other possible "exotic" phenomena that could be measured by ANTARES include nuclearites or magnetic monopoles.
environment, such as salinity
and oxygen
probes, sea current profilers and instrumentation for the measurement of light transmission and sound velocity. Also, a camera system has been installed for the automatic tracking of bioluminescent
organisms. Results from these instruments, while also important for the calibration of the detector, will be shared with ocean science institutes involved in the ANTARES collaboration.
While the ANTARES detector contains an acoustic positioning system for the alignment of the free-floating detector lines, it also houses a separate dedicated acoustic detection system AMADEUS, which will comprise 6 converted ANTARES storeys with hydrophones to evaluate the possibility for the acoustic detection of neutrinos in the deep sea. The first 3 of these acoustic storeys have been included in the instrumentation line, the other 3 on the 12th line.
Neutrino detector
A neutrino detector is a physics apparatus designed to study neutrinos. Because neutrinos are only weakly interacting with other particles of matter, neutrino detectors must be very large in order to detect a significant number of neutrinos. Neutrino detectors are often built underground to isolate...
residing 2.5 km under the Mediterranean Sea
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...
off the coast of Toulon
Toulon
Toulon is a town in southern France and a large military harbor on the Mediterranean coast, with a major French naval base. Located in the Provence-Alpes-Côte-d'Azur region, Toulon is the capital of the Var department in the former province of Provence....
, France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
. It is designed to be used as a directional Neutrino Telescope to locate and observe neutrino
Neutrino
A neutrino is an electrically neutral, weakly interacting elementary subatomic particle with a half-integer spin, chirality and a disputed but small non-zero mass. It is able to pass through ordinary matter almost unaffected...
flux
Flux
In the various subfields of physics, there exist two common usages of the term flux, both with rigorous mathematical frameworks.* In the study of transport phenomena , flux is defined as flow per unit area, where flow is the movement of some quantity per time...
from cosmic origins in the direction of the Southern Hemisphere
Southern Hemisphere
The Southern Hemisphere is the part of Earth that lies south of the equator. The word hemisphere literally means 'half ball' or "half sphere"...
of the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
, a complement to the northern hemisphere neutrino detector IceCube. The name comes from Astronomy with a Neutrino Telescope and Abyss environmental RESearch project; the acronym also being the name of the prominent star Antares
Antares
Antares is a red supergiant star in the Milky Way galaxy and the sixteenth brightest star in the nighttime sky . Along with Aldebaran, Spica, and Regulus it is one of the four brightest stars near the ecliptic...
. Other neutrino telescopes designed for use in the nearby area include the Greek
Greece
Greece , officially the Hellenic Republic , and historically Hellas or the Republic of Greece in English, is a country in southeastern Europe....
NESTOR
Nestor Project
The NESTOR Project is an international scientific collaboration whose target is the deployment of a neutrino telescope on the sea floor off Pylos, Greece.-Neutrino:...
telescope and the Italian
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
NEMO telescope, which are both in early design stages.
Design
The array contains a set of twelve separate vertical strings of photomultiplierPhotomultiplier
Photomultiplier tubes , members of the class of vacuum tubes, and more specifically phototubes, are extremely sensitive detectors of light in the ultraviolet, visible, and near-infrared ranges of the electromagnetic spectrum...
tubes. Each one has 75 optical modules and is about 350 meters long. They are anchored at the bottom of the sea at a depth of about 2.5 km, roughly 70 meters apart from each other. When neutrinos enter the southern hemisphere of the earth, they usually continue traveling directly through it. On rare occasions, a few muon
Muon
The muon |mu]] used to represent it) is an elementary particle similar to the electron, with a unitary negative electric charge and a spin of ½. Together with the electron, the tau, and the three neutrinos, it is classified as a lepton...
neutrinos interact with the water in the Mediterranean Sea. When this happens, they produce a high energy muon. ANTARES works by its photomultiplier tubes detecting the Cherenkov radiation
Cherenkov radiation
Cherenkov radiation is electromagnetic radiation emitted when a charged particle passes through a dielectric medium at a speed greater than the phase velocity of light in that medium...
emitted as the muon passes through the water. The detection techniques used discriminate between the signature of "upward-going muons", a muon neutrino that has had interactions with matter below the detector (the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
), and much higher flux of "downward atmospheric muons".
In contrast to the South Pole
South Pole
The South Pole, also known as the Geographic South Pole or Terrestrial South Pole, is one of the two points where the Earth's axis of rotation intersects its surface. It is the southernmost point on the surface of the Earth and lies on the opposite side of the Earth from the North Pole...
neutrino telescopes AMANDA
Antarctic Muon And Neutrino Detector Array
The Antarctic Muon And Neutrino Detector Array is a neutrino telescope located beneath the Amundsen-Scott South Pole Station. In 2005, after nine years of operation, AMANDA officially became part of its successor project, the IceCube Neutrino Observatory.AMANDA consists of optical modules, each...
and IceCube, ANTARES uses water instead of ice as its Cherenkov medium. As light in water is less scattered than in ice this results in a better resolving power
Angular resolution
Angular resolution, or spatial resolution, describes the ability of any image-forming device such as an optical or radio telescope, a microscope, a camera, or an eye, to distinguish small details of an object...
. On the other hand, water contains more sources of background light than ice (radioactive isotopes potassium
Potassium
Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...
-40 in the sea salt and bioluminescent organisms
Bioluminescence
Bioluminescence is the production and emission of light by a living organism. Its name is a hybrid word, originating from the Greek bios for "living" and the Latin lumen "light". Bioluminescence is a naturally occurring form of chemiluminescence where energy is released by a chemical reaction in...
), leading to a higher energy thresholds for ANTARES with respect to IceCube and making more sophisticated background-suppression methods necessary.
Construction history
The construction of ANTARES was completed on May 30, 2008, two years after the first string was deployed.Initial testing began in 2000. Equipment indirectly related to the detector such as a seismometer
Seismometer
Seismometers are instruments that measure motions of the ground, including those of seismic waves generated by earthquakes, volcanic eruptions, and other seismic sources...
were deployed in 2005. The first string of photomultiplier tubes was moved into place in February 2006. In September 2006 the second line was successfully connected. Lines 3, 4 and 5 were deployed at the end of 2006 and connected in January 2007. This was an important step that made Antares the biggest neutrino telescope in the Northern hemisphere (surpassing the Baikal neutrino telescope). Lines 6, 7, 8, 9, and 10 were deployed between March and early November 2007 and connected in December 2007 and January 2008. From May 2008 the detector has been running in its complete 12-line configuration.
Deployment and connection of the detector are performed in cooperation with the French oceanographic institute, IFREMER
Ifremer
Ifremer, standing for French Research Institute for Exploitation of the Sea is an oceanographic institution in France.- Scope of works :...
, currently using the ROV Victor, and for some past operations the submarine
Submarine
A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...
Nautile
Nautile
The Nautile is a manned submersible owned by Ifremer, the French Research Institute for Exploitation of the Sea. Commissioned in 1984, the submersible can be operated at depths of up to ....
.
Experimental goals
The ANTARES project is the counterpart to the IceCube Neutrino DetectorIceCube Neutrino Detector
The IceCube Neutrino Observatory is a neutrino telescope constructed at the Amundsen-Scott South Pole Station in Antarctica...
. The detection principles of the two projects are very similar, but they point toward opposite hemispheres. ANTARES will detect neutrinos from high energy origin, particularly in the range from
to electron-volts (100 GeVGEV
GEV or GeV may stand for:*GeV or gigaelectronvolt, a unit of energy equal to billion electron volts*GEV or Grid Enabled Vehicle that is fully or partially powered by the electric grid, see plug-in electric vehicle...
- 100 TeV
TEV
TEV may refer to:* TeV, or teraelectronvolt, a measure of energy* Total Enterprise Value, a financial measure* Total Economic Value, an economic measure* Tobacco etch virus, a plant pathogenic virus of the family Potyviridae....
). Over several years of operation, it may be able to produce a map of the neutrino flux
Flux
In the various subfields of physics, there exist two common usages of the term flux, both with rigorous mathematical frameworks.* In the study of transport phenomena , flux is defined as flow per unit area, where flow is the movement of some quantity per time...
from cosmic origins in the southern hemisphere. Of particular interest is the detection of astrophysical point sources of neutrinos, possibly in correlation with observations in other bands (such as gamma rays sources observed by the HESS
Hess
Hess or Heß may refer to:* People with the surname Hess * Hess Educational Organization, the largest private provider of English instruction in the Republic of China...
telescope in Namibia
Namibia
Namibia, officially the Republic of Namibia , is a country in southern Africa whose western border is the Atlantic Ocean. It shares land borders with Angola and Zambia to the north, Botswana to the east and South Africa to the south and east. It gained independence from South Africa on 21 March...
, which has a common field of view with ANTARES).
Apart from this astro-particle physics aspect, the ANTARES telescope will also tackle some fundamental problems in particle physics, such as the search for dark matter
Dark matter
In astronomy and cosmology, dark matter is matter that neither emits nor scatters light or other electromagnetic radiation, and so cannot be directly detected via optical or radio astronomy...
in the form of neutralino
Neutralino
In particle physics, the neutralino is a hypothetical particle predicted by supersymmetry. There are four neutralinos that are fermions and are electrically neutral, the lightest of which is typically stable...
annihilation
Annihilation
Annihilation is defined as "total destruction" or "complete obliteration" of an object; having its root in the Latin nihil . A literal translation is "to make into nothing"....
in the sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
("normal" solar neutrinos being outside the energy range of ANTARES) or the galactic centre. Due to the very different methods employed, its expected sensitivity is nearly complementary to the direct dark matter searches performed by various experiments such as DAMA
DAMA
DAMA is a not-for-profit, vendor-independent, international association of technical and business professionals dedicated to advancing the concepts and practices of information resource management and data resource management .DAMA's primary purpose is to promote the understanding, development...
, CDMS
Cryogenic Dark Matter Search
The Cryogenic Dark Matter Search is a series of experiments designed to directly detect particle dark matter in the form of WIMPs. Using an array of semiconductor detectors at millikelvin temperatures, CDMS has set the most sensitive limits to date on the interactions of WIMP dark matter with...
and at the LHC
LHC
LHC may refer to:* Large Hadron Collider, a particle accelerator and collider located on the Franco-Swiss border near Geneva, SwitzerlandLHC also may refer to:* La hora Chanante, a Spanish comedy television show...
. Detection of neutralino signals would also confirm supersymmetry
Supersymmetry
In particle physics, supersymmetry is a symmetry that relates elementary particles of one spin to other particles that differ by half a unit of spin and are known as superpartners...
. Other possible "exotic" phenomena that could be measured by ANTARES include nuclearites or magnetic monopoles.
Additional instrumentation
In addition to the main optical detector for cosmic neutrinos, the ANTARES experiment also houses a number of instruments for the study of the deep seaDeep sea
The deep sea, or deep layer, is the lowest layer in the ocean, existing below the thermocline and above the seabed, at a depth of 1000 fathoms or more. Little or no light penetrates this part of the ocean and most of the organisms that live there rely for subsistence on falling organic matter...
environment, such as salinity
Salinity
Salinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates...
and oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
probes, sea current profilers and instrumentation for the measurement of light transmission and sound velocity. Also, a camera system has been installed for the automatic tracking of bioluminescent
Bioluminescence
Bioluminescence is the production and emission of light by a living organism. Its name is a hybrid word, originating from the Greek bios for "living" and the Latin lumen "light". Bioluminescence is a naturally occurring form of chemiluminescence where energy is released by a chemical reaction in...
organisms. Results from these instruments, while also important for the calibration of the detector, will be shared with ocean science institutes involved in the ANTARES collaboration.
While the ANTARES detector contains an acoustic positioning system for the alignment of the free-floating detector lines, it also houses a separate dedicated acoustic detection system AMADEUS, which will comprise 6 converted ANTARES storeys with hydrophones to evaluate the possibility for the acoustic detection of neutrinos in the deep sea. The first 3 of these acoustic storeys have been included in the instrumentation line, the other 3 on the 12th line.