Neutrino speed at OPERA

beam trajectory

 The OPERA experiment has recently announced a measurement that contradicts one of the consequences of the special theory of relativity: that matter cannot travel faster than the speed of light. The OPERA experiment is a long-baseline neutrino experiment with the detector based in an underground laboratory in the Gran Sasso mountain. The experiment utilises a high intensity beam of muon neutrinos produced at CERN by the CERN Neutrinos to Gran Sasso (CNGS) facility. The experiment has studied more than 16,000 neutrino events collected over 3 years of running and has used timing information based on the produced neutrinos at CERN and those detected in the OPERA detector to measure the time of flight of the muon neutrino from CNGS to OPERA. The measured time is then compared with the predicted time assuming neutrinos travel at the speed of light. The experiment has detected a discrepancy of 60ns with the measured neutrinos arriving earlier at the detector than predicted. A possible cause of the early arrival could be that neutrinos travel faster than the speed of light. Particle Physicists at QMUL are well placed to verify this observation at the T2K long-baseline neutrino experiment in Japan in the future with an improved system.