Leaders of faster-than-light neutrino team resign

A month after revealing errors in their high-profile claim that subatomic neutrinos had been clocked traveling faster than the speed of light, two leaders of the Italian OPERA collaboration have resigned. Both spokesman Antonio Ereditato of the University of Bern in Switzerland and physics coordinator Dario Autiero of Lyon’s Institute of Nuclear Physics in France, who presented the stunning result in September 2011 to a packed auditorium at CERN (pictured), sent out resignations today.

Autiero says that both men have been concerned about the existence of a large split within OPERA’s 170-strong collaboration, and want to make way for an alternative leadership that can provide more unity. Ereditato, reached by phone, says firmly, “my comment is no comment.”

OPERA had clocked neutrinos traveling 730 kilometres from CERN near Geneva, Switzerland, to Gran Sasso National Laboratory near L’Aquila, Italy, finding that they arrived 60 nanoseconds faster than a light beam would do. This seemed to conflict with Einstein’s Special Theory of Relativity, which bans faster-than-light travel. But a subsequent investigation of the experiment’s systematics revealed a troublesome cable and timing device that cast doubt on the certainty of the result. OPERA still plans to repeat its measurement in May with the goal of quantifying the effect of its errors.

Autiero denied that he was stepping down because of mistakes in the measurement, saying that the discovery of an unknown systematic error is an inevitable hazard for any scientist doing a precision measurement. “In science you cannot pretend to be the owner of any absolute truth,” he says. Instead, he says that he and Ereditato felt that tensions that had always existed within OPERA were becoming impossible to bridge. He acknowledges that these were exacerbated by the publication of the provocative result, with some complaining from the beginning that the findings were likely to be wrong. He also agrees that the spectacular degree of media attention has brought pressure to bear. Despite the fact that OPERA itself never claimed to overturn Einstein’s theory, keeping its claims narrowly to the report of an anomalous measurement, many newspapers depicted it that way. ‘They played with the sensationalism of the story,” he says.

Yves Declais, also of Lyon’s Institute of Nuclear Physics in France, who was spokesman of OPERA from 2002 to 2008, says that OPERA has always been difficult to lead. There are cultural splits between the Italians and Northern Europeans, and a lot of personality conflicts that make it hard to have a quiet scientific discussion, he says. He believes that part of the problem is that the leaders are elected by a collaboration board of 20–30 people, consisting of one person from each participating institution, and not by the whole collaboration, so many do not feel it is truly representative.

Ereditato’s resignation was first reported by Reuters. His and Autiero’s resignations were unexpected, and Autiero suggests that it may take some weeks for OPERA to elect successors.

Update: Physics World reports that the resignations followed a vote of ‘no confidence’, which, although it did not carry with enough votes to require a change of leadership, made clear that the majority of researchers in the collaboration were no longer supportive.

Update 31 March: Antonio Ereditato has issued a lengthy public statement, echoing Autiero’s account of the resignation, and again taking a swipe at the media for, he says, sensationalizing the result and putting pressure on the collaboration. He says he did everything he could to dissipate tensions in the project, but when these turned into open criticism, “I felt that the time had come for me to tender my resignation in order to foster a new, more widely-shared consensus.”

Image: Dario Autiero’s September 2011 Seminar/CERN

Faster-than-light neutrino measurement has two possible errors

The OPERA collaboration, which made headlines in September with the revolutionary claim to have clocked neutrinos travelling faster than the speed of light, has identified two possible sources of error in its experiment. If true, its result would have violated Einstein’s Special Theory of Relativity, a cornerstone of modern physics.

OPERA had collected data suggesting that neutrinos generated at CERN near Geneva, Switzerland, and sent 730 kilometres to its detector at Gran Sasso National Laboratory in Italy were arriving 60 nanoseconds faster than a light beam would take to travel the same distance. Many physicists were skeptical but the measurement seemed to have been done carefully and reached a statistically significant level.

But according to a statement OPERA began circulating today, two possible problems have now been found with its set-up. As many physicists had speculated might be the case, both are related to the experiment’s pioneering use of Global Positioning System (GPS) signals to synchronize atomic clocks at each end of its neutrino beam. First, the passage of time on the clocks between the arrival of the synchronizing signal has to be interpolated, and OPERA now says that this may not have been done correctly. Second, there was a possible faulty connection between the GPS signal and the OPERA master clock.

An anonymously sourced account on Science Insider today broke the news that OPERA may have made a mistake. That report says that the faulty connection can account exactly for the 60-nanosecond effect. OPERA’s official statement stops short of that, saying instead that its two possible sources of error point in opposite directions and it is still working things out. Its statement reads, in full:

The OPERA Collaboration, by continuing its campaign of verifications on the neutrino velocity measurement, has identified two issues that could significantly affect the reported result. The first one is linked to the oscillator used to produce the events time-stamps in between the GPS synchronizations. The second point is related to the connection of the optical fiber bringing the external GPS signal to the OPERA master clock.

These two issues can modify the neutrino time of flight in opposite directions. While continuing our investigations, in order to unambiguously quantify the effect on the observed result, the Collaboration is looking forward to performing a new measurement of the neutrino velocity as soon as a new bunched beam will be available in 2012. An extensive report on the above mentioned verifications and results will be shortly made available to the scientific committees and agencies.

Caren Hagner, a member of OPERA at the University of Hamburg in Germany, says: “For the moment the collaboration decided not to make a quantitative statement, because we have to recheck and discuss the findings more thoroughly.”

At Fermilab, members of the MINOS collaboration (Main Injector Neutrino Oscillation Search) continue to try to make their own independent measurement of the speed of neutrinos, with initial results expected later this year.