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  11-09-2006: GREEN LIGHT FOR THE NEUTRINO BEAM FROM CERN TO GRAN SASSO  
 COMPLETE LIST 
Opera detector's detail
Opera detector's detail

© Copyright LNGS-INFN The use of photos is free of charge. Please request authorisation from the INFN Communication Office


it will provide information about the mysterious phenomenon of neutrino oscillation

The delivery of the neutrino beam (Cngs) from Cern and the beginning of a new generation of experiments were officially celebrated today at Infn (Italian National Institute for Nuclear Physics) National Laboratories of Gran Sasso with the participation of Fabio Mussi, Minister of Universities and Research.

The Cngs beam and the experimental devices constructed in the Gran Sasso Laboratories to study neutrino interactions are part of a project aimed at shedding light on the mysterious phenomenon of the oscillation of these particles.

Neutrinos are continuously produced in nuclear reactions within the stars, and they are the most abundant particles in the Universe after photons. Our planet is constantly traversed by their flux: each second, 60 billion neutrinos go through a fingertip. They interact so weakly with other particles that they can go through any form of matter without leaving a trace. This peculiarity makes neutrinos so elusive that a great sensitivity is required in the design of experiments to study them. Neutrinos are divided into three families: electron, muon and tau. Experimental evidence obtained through both cosmic and man-made neutrinos shows that they can oscillate from one type into another. This important phenomenon implies that each type of neutrino has a mass, and that the masses of the three types are different.

“The existence of a mass for these particles sheds light on some of the most important problems of modern physics,” explains Roberto Petronzio, Infn President. “For example, the existence of neutrino mass could help to explain the so-called asymmetry between matter and antimatter, that is to say the prevalence of matter in the Universe, in spite of the nearly perfect similarity of their fundamental interactions”.

By virtue of the oscillation phenomenon, a beam of neutrinos that is initially homogeneous, detected after some time, would contain within it another kind of neutrino. Experiments at the Gran Sasso Laboratories, which use the neutrino beam from Cern, will be able to demonstrate in particular the transformation of muon neutrinos into tau neutrinos, a phenomenon never so far observed. Only muon neutrinos will be produced at Cern, but after 2,5 milliseconds, when the beam arrives at Gran Sasso after having covered about 730 kilometers at the speed of light, a very small number of tau neutrinos are expected to be detected by the researchers. According to some theoretical calculations, among many billions of billions of muon neutrinos arriving at Gran Sasso, only about 15 tau neutrinos will be identified.

At Cern, neutrinos are generated from collisions of an accelerated beam of protons with a target. When protons hit the target, particles called pions and kaons are produced. They quickly decay, giving rise to neutrinos. Unlike charged particles, neutrinos are not sensitive to the electromagnetic fields usually used by physicists to change the trajectories of particle beams. Neutrinos can pass through matter without interacting with it; they keep the same direction of motion they have from their “birth”. Hence, as soon as they are produced, they maintain a straight path, passing through the earth’s crust. For this reason, it is extremely important that from the very beginning the beam points exactly towards the laboratories at Gran Sasso.

At Gran Sasso two experiments will be waiting for the neutrinos from Cern: Opera, and, eventually, Icarus, the latter still under construction. Opera is an enormous detector weighing 1.800 tons, made up of photographic plates interleaved with lead layers. The very few tau neutrinos produced from neutrino oscillation, interacting with the lead layers, will generate very short-lived charged particles (called tau leptons) whose decay products will leave marks in the photographic emulsions. The reconstruction of these traces will allow experimenters to identify the tau lepton and so detect the presence of tau neutrinos in the beam. The Icarus apparatus will instead use a detector of 600 tons of liquid argon. The products of the interaction among neutrinos and argon atoms will be registered by a series of sophisticated sensors plunged into the liquid itself. The experiments are located at the Gran Sasso Laboratories where they are sheltered by 1.440 metres of rock, a very powerful screen against the cosmic rays produced in the atmosphere by primary cosmic radiation. Cosmic rays produce a storm of charged particles that constantly hit our planet. Without the protection of rock, the “noise” from cosmic rays would drown out the very weak signal of the few interactions of neutrinos in the detectors.

Cngs experiments are an integral part of the strategy for particle physics conceived by the Cern Council for the next ten years, expressed in a series of guidelines approved last 14 July in Lisbon.
The development of a common strategy for nuclear particle physics in Europe is necessary because of the scale of research in this field for the near future. Therefore coordinating among Cern, research centres and National Laboratories is more than ever necessary. A joint experiment between Cern and the Laboratories of Gran Sasso therefore embodies the ideal inauguration of the new direction approved in Lisbon.

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Photos and animations of the experiment are available on line to be used in web pages and in television broadcasts
www.infn.it/comunicazione/CNGS

For further information about Laboratories visit the website: http://www.lngs.infn.it


 RELATED SITES 

 RECENT NEWS  
26-03-2013: OPERA observed a third neutrino tau
08-06-2012: Neutrinos sent from CERN to Gran Sasso respect the cosmic speed limit
06-06-2012: OPERA OBSERVES THE SECOND TAU NEUTRINO
18-05-2012: FEL, A SUPER LASER FOR SUPERB
15-05-2012: Research on neutrinos allows the discovery of vortices in the abysses of the eastern Mediterranean
16-03-2012: The Icarus experiment measures the neutrino speed: even neutrinos are not faster than light
23-02-2012: NEUTRINOS: STATEMENT ISSUED BY THE OPERA COLLABORATION
13-12-2011: ato attuale della ricerca dell’Higgs
18-11-2011: NEW TESTS CONFIRM THE RESULTS OF OPERA ON THE NEUTRINO VELOCITY. BUT IT IS NOT YET THE FINAL CONFIRMATION
26-10-2011: Fernando Ferroni appointed as the president of the Italian National Institute for Nuclear Physics

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