Since September 23rd, when the OPERA collaboration announced they had discovered neutrinos travelling faster than the speed of light, the laws of physics have not collapsed and are still standing strong. The vast majority of physicists, even the ones conducting the experiment, believe that they had made a mistake (http://xkcd.com/955/).
However, since then the team have been trying to find out what this mistake is. They decided to repeat the experiment, but this time they altered the structure of the proton beam. They changed the proton beam from 10.5 microseconds long to only 3 nanoseconds long. This modification helped the team identify individual particles when they were fired out and when they arrived at there destination. But this new result only supports the previous findings.
“This is reinforcing the previous finding and ruling out some possible systematic errors which could have in principle been affecting it,” said Antonio Ereditato of the Opera collaboration.
CERN have provided an update on the muon-neutrino time of flight measurement performed by the OPERA Collaboration, which I shall now quote:
“Following the OPERA collaboration’s presentation at CERN on 23 September, inviting scrutiny of their neutrino time-of-flight measurement from the broader particle physics community, the collaboration has rechecked many aspects of its analysis and taken into account valuable suggestions from a wide range of sources. One key test was to repeat the measurement with very short beam pulses from CERN. This allowed the extraction time of the protons, that ultimately lead to the neutrino beam, to be measured more precisely.
The beam sent from CERN consisted of pulses three nanoseconds long separated by up to 524 nanoseconds. Some 20 clean neutrino events were measured at the Gran Sasso Laboratory, and precisely associated with the pulse leaving CERN. This test confirms the accuracy of OPERA’s timing measurement, ruling out one potential source of systematic error. The new measurements do not change the initial conclusion. Nevertheless, the observed anomaly in the neutrinos’ time of flight from CERN to Gran Sasso still needs further scrutiny and independent measurement before it can be refuted or confirmed.
On 17 November, the collaboration submitted a paper on this measurement to the peer reviewed Journal of High Energy Physics (JHEP). This paper is also available on the ArXiv preprint server.”