New tests support previous result of faster than light neutrinos

The CERN results in September indicating faster than light neutrinos have stood up to one set of tests to check the result.

Reuters:

The new experiment at the Gran Sasso laboratory, using a neutrino beam from CERN in Switzerland, 720 km (450 miles) away, was held to check findings in September by a team of scientists which were greeted with some skepticism. Scientists at the Italian Institute for Nuclear Physics (INFN) said in a statement on Friday that their new tests aimed to exclude one potential systematic effect that may have affected the original measurement. ….

An international team of scientists shocked the scientific world with the original findings in September. That first finding was recorded when 15,000 neutrino beams were pumped over three years from CERN to Gran Sasso, an underground Italian laboratory near Rome.

Physicists on the experiment, called OPERA after the initials of its formal scientific title, said they had checked and rechecked over many months anything that could have produced a misreading before announcing what they had found. …

.. one potential source of error in the first results was that the pulses of neutrinos sent by CERN were relatively long at around 10 microseconds each, so measuring their exact arrival time at Gran Sasso could have had relatively large errors.

To account for this, the beams sent by CERN in this latest experiment were around three nanoseconds shorter, with large gaps of 524 nanoseconds between them, meaning the scientists at Gran Sasso would time their arrival more accurately.

“In this way, compared to the previous measurement, the neutrinos bunches are narrower and more spaced from each other,” the scientists said. “This permits to make a more accurate measure of their velocity at the price of a much lower beam intensity.”

Jacques Martino, director of the French National Institute of Nuclear and Particle Physics, who worked on the second experiment, said that while this test was not a full confirmation, it did remove some of the potential systematic errors that may have occurred in the first one.

Measurement of the neutrino velocity with the OPERA detector in the CNGS beam   http://arxiv.org/abs/1109.4897v2

The OPERA neutrino experiment at the underground Gran Sasso Laboratory has measured the velocity of neutrinos from the CERN CNGS beam over a baseline of about 730 km with much higher accuracy than previous studies conducted with accelerator neutrinos. The measurement is based on high-statistics data taken by OPERA in the years 2009, 2010 and 2011. Dedicated upgrades of the CNGS timing system and of the OPERA detector, as well as a high precision geodesy campaign for the measurement of the neutrino baseline, allowed reaching comparable systematic and statistical accuracies. An early arrival time of CNGS muon neutrinos with respect to the one computed assuming the speed of light in vacuum of (57.8 \pm 7.8 (stat.)+8.3-5.9 (sys.)) ns was measured. This anomaly corresponds to a relative difference of the muon neutrino velocity with respect to the speed of light (v-c)/c = (2.37 \pm 0.32 (stat.) (sys.)) \times10-5. The above result, obtained by comparing the time distributions of neutrino interactions and of protons hitting the CNGS target in 10.5 {\mu}s long extractions, was confirmed by a test performed using a beam with a short-bunch time-structure allowing to measure the neutrino time of flight at the single interaction level.

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One Response to “New tests support previous result of faster than light neutrinos”

  1. CERN OPERA’s FTL neutrinos are rejected by CERN ICARUS scientists « The k2p blog Says:

    […] FTL neutrinos to widespread scepticism, wonder and some delight. Last Friday the OPERA scientists reported that new experiments supported the September […]

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