# IPMU Colloquium

Speaker: Masahiro Komatsu (OPERA Collaboration (Nagoya)) Measurement of the neutrino velocity with the OPERA detector in the CNGS beam Thu, Oct 20, 2011, 15:30 - 17:00 Lecture Hall 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 730 km with unprecedented accuracy. The measurement is based on the high-statistics data taken by OPERA in the years2009, 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 \pm 6.9(stat.) \pm 7.4(sys.)) ns was measured. This unexpected anomaly corresponds to a relative difference of the muon neutrino velocity with respect to the speed of light (v-c)/c = (2.48 \pm 0.28(stat.) \pm 0.30(sys.)) \times 10^{-5}.