Neutreno Experiment
Tomorrow, researchers from CERN will be releasing experiment results that suggest neutrinos, the lightest particles we're aware of, may be moving slightly faster than the speed of light. Neutrinos have generally made the news because they engage in what are called flavor oscillations, in which (to give one example) an experiment that creates only muon neutrinos will see some of them behave as electron neutrinos when they hit a detector. "MINOS also measured a faster-than-light value of the neutrino speed," MINOS co-spokesperson Jenny Thomas told Ars, "but the errors were so big we dismissed it." Errors in any one of these factors can introduce errors into the results. CERN has a similar, higher-energy version of the Fermi experiment called OPERA, which sends neutrinos from a source in Switzerland to a detector at Gran Sasso in Italy. Neutrinos from supernovae are relatively low energy; MINOS' were much higher, at which point a weak effect turned up. The physics world is abuzz with news that a group of European physicists plans to announce Friday that it has clocked a burst of subatomic particles known as neutrinos breaking the cosmic speed limit - the speed of light - that was set by Albert Einstein in 1905. If true, it is a result that would change the world. But that "if" is enormous. Incredible claims require incredible evidence. "These guys have done their level best, but before throwing Einstein on the bonfire, you would like to see an independent experiment," said John Ellis, a CERN theorist who has published work on the speeds of the ghostly particles known as neutrinos. According to scientists familiar with the paper, the neutrinos raced from a particle accelerator at CERN outside Geneva, where they were created, to a cavern underneath Gran Sasso in Italy, a distance of about 450 miles, about 60 nanoseconds faster than it would take a light beam. Einstein himself - the author of modern physics, whose theory of relativity established the speed of light as the ultimate limit - said that if you could send a message faster than light, "You could send a telegram to the past." The group that is reporting the results is known as OPERA, for Oscillation Project with Emulsion-Tracking Apparatus. Antonio Ereditato, the physicist at the University of Bern who leads the group, agreed with de Rejula and others who expressed shock. Neutrinos are among the weirdest denizens of the weird quantum subatomic world. de Rujula pointed out however, that it was impossible to identify which protons gave birth to which neutrino, leading to statistical uncertainties. That group found, though with less precision, that the neutrino speeds were consistent with the speed of light. “This result comes as a complete surprise,” said OPERA spokesperson, Antonio Ereditato of the University of Bern. While OPERA researchers will continue their studies, we are also looking forward to independent measurements to fully assess the nature of this observation.” To get the job done, the OPERA Collaboration joined forces with CERN metrology experts and other facilities to establish absolute calibrations. There cannot be any error margin in parameters between the source and detector distances – and the neutrino’s flight time. In this circumstance, the measurements of the initial source of the neutrino beam and OPERA has an uncertainty value of 20 cm over the 730 km. “Today’s seminar is intended to invite scrutiny from the broader particle physics community.”
