Precision measurement of the neutrino velocity with the ICARUS detector in the CNGS beam

Abstract

During May 2012, the CERN-CNGS neutrino beam has been operated for two weeks for a total of 1:8 1017 p.o.t., with the proton beam made of bunches, few ns wide and separated by 100 ns. This beam structure allows a very accurate time of ight measurement of neutrinos from CERN to LNGS on an event-by-event basis. Both the ICARUS-T600 PMT-DAQ and the CERN-LNGS timing synchronization have been substantially improved for this campaign, taking advantage of additional independent GPS receivers, both at CERN and LNGS as well as of the deployment of the \White Rabbit" protocol both at CERN and LNGS. The ICARUS-T600 detector has collected 25 beam-associated events; the correspond- ing time of ight has been accurately evaluated, using all di erent time synchroniza- tion paths. The measured neutrino time of ight is compatible with the arrival of all events with speed equivalent to the one of light: the di erence between the expected value based on the speed of light and the measured value is t = tofc􀀀tof = 0:10 0:67stat: 2:39syst: ns. This result is in agreement with the value previously reported by the ICARUS Collaboration, t = 0:3 4:9stat: 9:0syst: ns, but with improved statistical and systematic accuracy.