Friday, September 23, 2011

Neutrinos Moving Faster Than c?

The big news right now, of course, is the report out of the OPERA collaboration at CERN of the apparent measurement of neutrinos moving faster than c.

The OPERA team fires muon neutrinos from the Super Proton Synchrotron at CERN in Geneva a distance of 730 km under the Alps to a detector in Gran Sasso, Italy. The team studied more than 15,000 neutrino events and found that they indicate that the neutrinos travel at a velocity 20 parts per million above the speed of light.
This will be big if true. So before jumping up and down that this is a major discovery, we will have to wait for several verifications, and certainly with experiments with high resolutions.

BTW, the article had a typo in one of its paragraphs:

This is not the first time that a neutrino experiment has glimpsed superluminal speeds. In 2007 the MINOS experiment in the US looked at 473 neutrons that travelled from Fermilab near Chicago to a detector in northern Minnesota. MINOS physicists reported speeds similar to that seen by OPERA, but their experimental uncertainties were much larger. According to the OPERA researchers, their measurement of the neutrino velocity is 10 times better than previous neutrino accelerator experiments.
 That "neutrons" should obviously be "neutrinos". As with OPERA, the MINOS experiment (which I've mentioned on this blog a few times) involves shooting neutrinos from Fermilab to a detector in Soudan, Minnesota.



Unknown said...

They are doing a live webcast right now (startd 16:00 CNT):

Pi-Guy said...

I think this calls for a time-of-flight study over a much longer distance. Can the beam signal be detected at the South Pole? Can it be steered to Soudan?

Kea said...

Pi-Guy, I believe that the geodesy is more accurate when both sites can view the same satellite.

Anonymous said...

Did not Bilaniuk and Sudarshan show in the 1960's (Physics Today, v22, No. 5) that elementary special relativity admits tachyons, but a tachyon cannot become a tardyon or v.v. because an infinite amount of energy would be required either way? So can a tachyon be generated by a collision at CERN? What's the real issue here?

SFG said...

Supernova 1987a was about 168,000 lightyears away. If I'm doing my math right, superluminal neutrinos should have arrived about 3 years early. I know neutrinos from 1987a were detected in 1987. Any evidence for early arrivals?