The aspirations of each and the other joinA haute couture of first lady but not onlyThe European highspeed network will triple by 2020And it is the same in the rest of the worldThis reform requires a readjustment of the cantons5 for the iPhone and 6 for the Sony ReaderThe success of La Banque Postale is WernerBut very quickly and tension have emergedAt the age of fiftytwo Patricia Donnelly has known only two employersThe drunken boat of GM continually more and moreMore than 1,800 tons of lead, a hedge of honor of 732 kilometres, EUR 104 million and the beauty of Abruzzi to shroud. Europe has not homework to attract the current diva of the particle physics in Europe. Neutrinos have now their scene, well-appointed laboratory "opera", inaugurated the week last in Italy. This is not the reputation of the local barons vibrato that inspired this program, but the quality of Italian physicists and the proximity of the CERN. Because it is the Franco-Swiss centre that will produce the neutrino beam directly derived from one of its large accelerators. To isolate them cosmic background noise, these particles will be expelled under the ground, under the protection of the Alps, the Italy direction. Online focus, the huge Opera detector is enshrined under a mountain for the same reasons. But it is the distance between the two ends of the experience that the originality of the European initiative. Hundreds of kilometres should be sufficient to cause the phenomenon of oscillation of the neutrino trace forward physicists.
Because Neutrino Physics has become in recent years, the dynamic particle physics branch. It is only a quarter of the publications. Among astrophysicists, the particles represent the last opportunity to save the theory of matter and antimatter. They hope to understand why the universe contains more antimatter dropped the big bang, while most of the particles have an alter ego, their anti-particule. The researchers also thought time that neutrinos would be the famous missing mass of the universe. It is known since that they are too light to make the weight.
Physicists are on the other hand on neutrinos to sorting in the variety of theories candidates to the unification of the standard model. Researchers who have toured other particles, the last new of the bestiary of particle could provide useful to the puzzle pieces. "We have, for example, decades of experience on quarks.". "Thanks to neutrinos, it get additional data to eliminate models that do not stick with them", advance Henri Pessard, researcher in the LAPP of Annecy and representative French Opera.
Neutrinos are the most mysterious individuals of particle physics. Surprisingly, when we know that they abound in the universe: our skin receives 65 billion neutrinos per second per square centimeter, for the particles emitted by the Sun. The problem is that they are exempt from seizure. Unlike the others, they are sensitive to one of the three fundamental forces, the weak force, and do so almost not fit by interaction with matter. Most safely across our planet. Cannot guess through rare releases of particles that causes their shock with atoms.
In recent years, European, Japanese and American work have still managed to break through a few secrets. All left the measurement of the flux from the Sun. Detectors accounted less particles that theory suggested. It is then that physicists have understood that there is not one but three types of neutrinos: neutrino electron, the muon, 200 times more "heavy" neutrino and the tau, 6,000 times neutrino "heavier".
Today, it remains a hypothesis to lift to the particle model. Researchers estimate that each type of neutrino can be transformed into another type. In 1998, the Japanese experience of Superkamiokande showed indirectly this oscillation phenomenon by pointing to losses in the mixture of neutrinos penetrating the atmosphere. Current experience in the Canada is proof by measuring the flow of the three types of electronic neutrino. This is a result capital since it demonstrates that these particles have mass, even low.
Opera has to go even further by studying not an overall but precise oscillation, those of the type tau neutrino in muon neutrino. The CERN accelerator will produce muon neutrinos in a beam sufficiently convergent to "water" the laboratory of the Gran Sasso on 2 km wide. According to the predictions of researchers during their journey, a number of the muon neutrino should turn into neutrinos taus. Opera has been sized to detect the particle, a still more capricious than the other two diva. As the tau particle, as a result of his collision with matter leaves only a very short track, a few hundred Micron against a few metres to a muon.
Therefore, it took deploy heavy artillery to capture this moment fugitive. The detector measures 7 metres wide and accumulates more than 230,000 bricks. Each of these brick contains sandwich 56 sheets of lead of a millimeter in thickness, associated to a photographic emulsion. Tau neutrinos which will have the misfortune of hitting the atoms of lead "réincarneront" in a tau particle leaving its short trace in the photographic gel.
The small set of researchers is to find in this heavy haystack the tiny needle, which will have undergone a "juice". Because the five years of experience, the detector will be crossed of 34,000 billion neutrinos, but only 30,000 interactions are expected with only 150 due to neutrinos taus and big ten really certifiable. Fortunately for them, the detector is highly automated. An electronic sensor will identify the affected area, and then modelling will determine the suspect brick. It will be retrieved by a robot, which will develop the photographic emulsions. The microscope of Opera promises then to identify the spectrum of the tau neutrino. Beginning of the end of October stalking.
