Etudes des proprietes des neutrinos dans les contextes ...

tel-00450051, version 1 - 25 Jan 2010
Chapter 2
Neutrino oscillations: the
experimental results and
perspectives
Since the first neutrino experiment in 1956 by Cowan and Reines [36], incredible
progress has been made in the search for neutrino properties. One of the most important
one is the discovery of the oscillation phenomenon by Super-Kamiokande
in 1998. Many neutrino experiments are currently running and several future
experiments have been financially approved. Their goal is the same, improve our
knowledge of the MNSP matrix and in particular experiments are rather turned
to the improvement of the third mixing angle, the CP-violation phase (which are
the two unknown parameters of the mixing matrix) and search to discriminate
the hierarchy of neutrinos 1 .
2.1 The solar data: θ12 and ∆m 2 21
2.1.1 The Standard Solar Model (SSM)
In the 20’s, Eddington advocated the theory that proton-proton reactions were
the basic principle by which the Sun and other stars burn. In the 30’s, another
process for the stars to burn was proposed by Weizsäcker and Bethe [28] independently
in 1938 and 1939, it is called the CNO cycle. Those two processes imply
an important production of electron neutrinos. Later on, it became clear that
stars are powerful neutrino sources.
By the 1960’s our understanding of the solar interior, and of low energy nuclear
physics, had reached such a stage that the Sun’s output could be predicted with
1 One of the main concerns is the question of their nature, i.e whether they are Dirac or
Majorana types. See appendix A for a brief discussion. Other open issues concern for instance
the neutrino magnetic moment, or the existence of sterile neutrinos.
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