Etudes des proprietes des neutrinos dans les contextes ...

tel-00450051, version 1 - 25 Jan 2010
1. Super-Beams. The first generation of neutrino super-beams, T2K and
NOνA, will study the νµ → νe channel which is sensitive to θ13 and δ.
The experiments will start by running in neutrino mode. Neutrino running
alone, however, implies that the experiments have no sensitivity to δ.
A second generation of upgraded superbeams, such as T2HK or the SPL,
could follow. The extremely large data sets provided by these experiments
would yield sensitivity to much smaller values of θ13. These experiments
could also search for CP-violation by running with anti-neutrinos, if θ13 is
large enough.
2. Neutrino Factory. The neutrino factory, often called the ultimate neutrino
facility, will be required if θ13 is too small for other facilities to be able to
measure δ. It will also allow to measure the neutrino hierarchy by exploiting
matter effects in the Earth (see Eq.(1.58)). For these reasons it is considered
for many people as the ”ultimate” machine. This last experiment
distinguishes itself by the fact that the detectors will be able to discriminate
particles with a positive or a negative charge, and consequently, the
neutrinos from the anti-neutrinos.
A a summary for the potentiality of the future neutrino experiments we show
the discovery reach of the various facilities in sin 2 2θ13. The figure (2.7) shows
the fraction of all possible values of the true value of the CP phase δ (Fraction
of δCP) for which sin 2 2θ13 = 0 can be excluded at the 3σ confidence level as
a function of the true value of sin 2 2θ13. Of the super-beam facilities, the most
sensitive is the T2HK with the optimised parameter set. The SPL 9 super-beam
performance is similar to that of T2HK, while the performance of the WBB 10
is slightly worse. While the Beat-Beam seems to be a good option for sin 2 2θ13
in the range 3.10 −3 to 4.10 −4 , the neutrino factory will be the only option for
1.5 10 −5 < sin 2 2θ13 < 4.10 −5 . If Nature has decided for θ13 smaller that this
range astrophysics might play a pivotal role to identify it since one can get unique
features e.g. the supernova time signal if an explosion occur [68] (see chapter 6).
9 SPL is a very intense superbeam which could be hosted at CERN.
10 WBB is the proposal originally put forward by Brookhaven National Laboratory to use
an on-axis, long baseline, wide-band neutrino beam pointed to illuminate a water Cherenkov
detector.
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