Following the OPERA collaboration's presentation at CERN on Sept. 23, 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 Nov. 17, the collaboration submitted a paper on this measurement to the peer reviewed Journal of High Energy Physics.
- The OPERA Collaboraton. Measurement of the neutrino velocity with the OPERA detector in the CNGS beam. Journal of High Energy Physics, 2011; (submitted) [link]
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