E 'was laid and anchored on the seabed 3,500 meters deep off the coast of Pachino, Sicily, the first tower of the observatory for neutrinos KM3NeT-Italian project in which the National Institute of Nuclear Physics (INFN) plays a key role thanks to the contribution of its LNS (LNS). This latest success follows a few months after that of last May, when it was hooked on the seabed the first string. The apparatus employs structures detection of different types, towers and strings, of course, to optimize the response to a range as wide as possible energy of the particles studied.
The experiment, in the final conformation of this phase, will be constituted by a total of eight towers and twenty-four strings, in order to realize a three-dimensional matrix of sensors for the detection and measurement of astrophysical neutrinos of high energy. Upon its completion it will be so, the largest astrophysical neutrino telescope operating in the northern hemisphere. Will also serve as the first portion of the node Italian infrastructure of pan-European research KM3NeT, which has the ultimate goal of expanding the detector with additional two hundred structures of revelation, thereby overcoming the sensitivity of the IceCube neutrino telescope US, operating in the Antarctic ice. "Today's success is another important step toward building KM3NeT-Italy and then towards the completion of the node Italian European research infrastructure," said James Cuttone, project manager and director of Italian-KM3NeT LNS. The project KM3NeT has so far been largely financed by EU structural funds - for the Italian funds PON 2007-2013 - and is already included in the list of European research infrastructures selected by the European Strategy Forum on Research Infrastructures (ESFRI). The marine operation began with the installation of the first of the three junction box that act as nodes for the two-way communication between devices submarines and train data acquisition of land of Portopalo. The junction box is also designed to distribute electrical power supplied to the equipment submarines. They were also installed and connected the cables interconnecting the tools at sea and the electro-optical cable main, connecting the site situated 100 km from the coast. Next, it was laid on the seabed and connected
to the junction box in the tower in its compact configuration (size and shape comparable to a container). Once verified the full operation of all the equipment is imparted to the tower opening command, by means of a wire guided underwater robot (ROV). A shot of the buoy depth placed on the top of the tower has allowed, then, the system to assume its final configuration work: the tower consists of a vertical sequence of 14 trusses aluminum (floors) of 8 meters in length, each host six optical sensors and two aids. The plans, interconnected through peaks in synthetic material, are spaced vertically to obtain a total height of the tower of about 400 meters. "Both the design and construction of the equipment, that the installation are particularly complex - explains Mario Musumeci, coordinator of the integration - particularly hostile operating environment because we are three and a half kilometers deep under the sea level without opportunity of maintenance of the systems. " "The installation led to the perfect coordination of the team who worked at the station for data acquisition of land and one on board the ship, - emphasizes Cuttone - and a special thanks goes to the team INFN, comprising Klaus Leismuller, Nunzio Randazzo and Giorgio Riccobene, that the ship Ambrosious Tide, in weather and sea conditions are not always ideal, coordinated shipboard operations ". In its final configuration the experiment will consist of a 'wilderness' of structures, that will form a grid volume of about one cubic kilometer. The towers and strings serve as the support for tens of thousands of optical sensors (photomultiplier), 'eyes' that will form the highly sensitive electronic underwater antenna capable of detecting the luminous wake bluish (called "Cherenkov light") produced from the rare interactions of neutrinos of astrophysical origin with seawater. The complex of towers will thus provide a telescope for high-energy cosmic neutrinos, which come from the center of our galaxy, after going through deep space and all the Earth, bringing about almost intact on their sources. International collaboration KM3NeT, in which Italy plays a decisive role with the National Institute of Nuclear Physics, adhere Cyprus, France, Germany, Greece, Ireland, Netherlands, United Kingdom, Romania, Spain. The undertaking involved nine groups INFN (Bari, Bologna, Catania, Genoa, LNF, LNS, Naples, Pisa, Rome), in collaboration and synergy with research institutes geophysical, oceanographic marine biology (INGV, CNR, CIBRA , NURC). The peculiarity of the neutrinos lies in the extremely low probability of interacting with matter: this characteristic allows them not to be absorbed by the background radiation and of cross unperturbed regions which are opaque to electromagnetic radiation, such as the inside of the astrophysical sources. Also, being neutral particles do not undergo deflections caused by galactic and intergalactic magnetic fields that would prevent to track the direction of origin. The price to pay for observing these particles so elusive is the need to achieve detectors of enormous dimensions. In addition, to protect themselves from the rain of cosmic radiation that targets the Earth, these detectors must be installed in heavily shielded. However, it is evident that devices of this size can not be placed in underground laboratories. A possible solution, then, is to use large volumes of a natural medium, providing it with appropriate instruments. In a transparent medium, such as water deep sea or polar ice, you can reveal the light radiation produced by the Cherenkov effect from secondary particles (muons), which generate the neutrinos interact with matter. Also, if you put the detector in the deep sea (or of polar ice), matter overlying doubles as a screen against the background of cosmic particles, which on the surface "would blind" the detector.