Neutrinos, the puzzling elementary particle, with neutral electric charge and tiny mass, interact with matter very rarely, and are among the most abundant particles in the Universe. They were predicted in the 1930's to maintain energy conservation in the nuclear beta decay and were observed only in 1956. There are 3 different types of massive neutrinos and they can transform into one another via the quantum process of “neutrino oscillations”, only possible if neutrinos have a non-zero mass. This was observed by the Sudbury Neutrino Observatory (SNO) experiment, solving the problem of the “missing solar neutrinos”. Besides this unique behavior, it is not excluded that neutrinos are Majorana particles, i.e. that a neutrino is its own anti-particle, with potential implications on the explanation of the matter/anti-matter asymmetry in the universe. The LIP neutrino physics team was created in 2005 to participate in SNO and integrated since the beginning (2006) the SNO+ experiment, for which the main goal is the observation of the extremely rare (if it exists) neutrinoless double beta decay (0NDBD) process to probe the possible Majorana character of neutrinos and measure its absolute mass. SNO+ reuses the SNO detector, that consists of a 12 m diameter spherical vessel, surrounded by about 9500 PMTs mounted on a geodesic structure, installed at a depth of 2 km in SNOLAB, Canada. SNO+ will use 780 tons of Tellurium-loaded liquid scintillator as the active medium. Besides the search for 0NDBD, measurements of neutrinos from the Sun, the Earth, Supernovae and nuclear reactors are also planned. The installation of the detector is in progress and it will be commissioned with water only before starting the scintillator fill in 2016. The LIP team carries out activities in several domains, from the optical calibration to the search of 0NDBD signals requiring the estimation of several types of backgrounds, but also in physics studies with reactor anti-neutrinos and geoneutrinos.

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Contacts

Group Leader:  

José Maneira