The new tests, completed 6 November, did away with the statistical analysis by splitting each pulse into bunches just 1- to 2-nanoseconds long, allowing each neutrino detected at Gran Sasso to be tied to a particular bunch produced at CERN. These tests were carried out over 10 days and provided 20 events. The researchers confirmed that the neutrinos arrived 60 nanoseconds early, with an uncertainty of about 10 nanoseconds, comparable to that of the initial result.
A major concern among the dissenters is the fact that the "time window" within which neutrinos were detected by OPERA in the most recent run had a width of 50 nanoseconds, something that the leader of the superluminal analysis, Dario Autiero, only revealed once the tests had been carried out. It was initially assumed that this window was just 10 nanoseconds wide. This difference does not affect the final result itself, the source notes, but dissenters say it highlights poor experimental procedure. Some researchers are also unhappy that only a small fraction of the analysis, which was carried out by Autiero, has been independently checked by others within the collaboration. This leaves open the possibility, they say, that not all possible errors have been accounted for.
The question of whether or not OPERA really has seen faster-than-light neutrinos will probably be settled only once the results of other experiments are in. Meanwhile, within OPERA, "People are exhausted," says the source. "Everyone should be convinced that the result is real, and they are not."