| アブストラクト: |
The OPERA neutrino experiment in the underground Gran Sasso Laboratory has
measured the velocity of neutrinos from the CERN CNGS beam over a baseline
of about 730km with unprecedented accuracy. The measurement is based on the
high-statistics data taken by OPERA in the years 2009, 2010 and 2011.
Dedicated upgrades of the CNGS timing system and of the OPERA detector, as
well as a high-precision geodesy campaign for the measurement of the
neutrino baseline allowed reaching comparable systematic and statistical
accuracies. An early arrival time of CNGS muon neutrinos with respect to
the one computed assuming the speed of light in vacuum of
(60.7+/-6.9(stat.)+/-7.4(sys.))ns was measured.
This unexpected anomaly corresponds to a
relative difference of the muon neutrino velocity with re-spect to the
speed of light (v-c)/c=(2.48+/-0.28(stat.)+/-0.30(sys.))*10^{-5}. |
