ANTARES (telescope)
The ANTARES neutrino telescope is a large undersea instrument that was built for the detection of neutrinos in the Mediterranean. It's on the ocean floor at a depth of about 2500 m, was built 30 km off the coast of Toulon in southern France. Creator and operator is a consortium of institutes, universities and research institutions from France, Germany, Italy, Russia and Spain. The research areas involved are astrophysics and astronomy, geophysics and oceanography. Antares is an acronym and stands for Astronomy with a Neutrino Telescope and Abyss Environmental Research.
History
In the summer of 1996 marks the start of scientists to prepare a study for the construction of a neutrino telescope in the Mediterranean group. Until 1999, the team have gathered data which should demonstrate that the project is at all feasible. In the final report environmental conditions, availability of the necessary technical capabilities as well as expected costs were compiled and issued a recommendation to follow up on the initiators. In December 1999, the first line (String) was built with detectors for the trial of the prototype in the sea. The prototype consisted of seven optical elements for the detection of associated components for positioning in the "space" (equal currents ), as well as power supply and calibration from the control panel. Six months later (June 2000), the string was dismantled and the data obtained. The results showed a good agreement with the expectations. In October 2001, about 40 km could be long " cable " successfully installed with the optical fibers for data transmission and one for the power supply and connected in December of the following year. On 17 March 2003, the first signals of the first provisional strings were received ( still in a prototype stage, but fully equip with all components ). The official inauguration of the Antares station took place on 18 November 2003. Was not until the beginning of 2006 was started with the installation of the final strings, and stores the first data in March. Until that time, the necessary infrastructure at the base of the site was built, consisting of lines, points of connection, as well as devices for other areas of research. So an earthquake in Japan has been registered with a magnitude of 6.2 with a belonging to the entire project seismometers in August 2005. Back in September of the same year (2006) the second string could be connected and put into operation. After five strings were in operation, the direction could be calculated from the reception of current signals for the first time in February 2007. It was in this case probably coming to an atmospheric neutrino from the southern Erdhemisphäre. On 30 May 2008, the last two strings could be installed and connected, which meant the completion of the currently largest undersea neutrino telescope.
Design and operation
Since neutrinos are practically massless and are not subject to as neutral electromagnetic interactions, they can be very difficult demonstrated. The detection of neutrinos at the Antares experiment is based on the Cherenkov principle. Pavel Alekseyevich Cherenkov discovered in 1934, the light - phenomenon and ordered it with his colleague Vavilov correctly the electromagnetic radiation of core elements to. Cherenkov was awarded in 1958 the Nobel Prize. The radiation occurs when a charged particle moves faster than the speed of light in the medium through this medium. The speed of light through the water, for example, is slower by almost a quarter than in the vacuum. A result of a nuclear reaction, which is caused by the neutrino, one charged secondary particles such as an electron or a muon, as Cherenkov radiation is when this particle is now moving faster than the speed of light in the medium, emitted. This effect is comparable to the sonic boom, occurs when an object is from subsonic speed is accelerated to a supersonic velocity. In this process, Cherenkov radiation is emitted, which makes, among other things in the visible wavelength range as Cherenkov light noticeable.
Due to the small cross sections for reactions of neutrinos with nuclei, detectors must be built according to a large scale in order to achieve a sufficient signal yield. The Antares - detector covered on the bottom of the sea an area of 10 hectares. This is relatively small compared to other neutrino detectors, but the shield for shielding the remaining particles is quite large: the entire diameter of the Earth. The detector elements are aligned to the bottom of the sea and thus register the neutrinos, which come from the southern celestial sphere. Virtually all charged particles ( ionized atoms, protons, electrons) are deflected more or less strongly by the Earth's magnetic field, but not the weakly interacting neutrinos. In this way, the direction and speed of the neutrinos can be determined by the spatially structured system with 12 strings arranged in about 1000 detector elements. The energy range in which it is measured, E > 10 GeV. At wavelengths between 400 to 500 nm, the selected photomultipliers operate most efficiently at the same time the transparency of the water in this area of the light is at its highest, which promises a good yield of data and information. The emission of Cherenkov light in the wavelength range from 285 to 400 nm is approximately twice as high as in the measured spectral range, the radiation in this wavelength range can not be utilized because of the photodetectors used.
News
On 24 June 2008, a fault in the power supply has been detected. The investigations revealed that a defect had to be present on the cable. The location of the defect was located 25 km distance from the coast. Repair work lasted about 5 days, with a portion of the cable must be replaced. The cause of the defect is the subject of ongoing investigations. On 6 September, the plant was handed over their operation.
Swell
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