Tag Archives: neutrinos

Physicists fail to find sterile neutrino

The uncertainty of science: A year’s collection of data using IceCube, a gigantic neutrino telescope built in the icecap of Antarctica, has found no evidence of a theorized fourth type of neutrino.

To search for sterile neutrinos, Halzen’s team looked for the arrival of muon neutrinos that started life on the other side of Earth. These were originally produced by the collision of cosmic rays with air molecules in the atmosphere, and passed through the planet to reach the detector. The IceCube team hoped to find a dearth of muon neutrinos at particular energies. That would have suggested that some muon neutrinos had temporarily mutated into sterile neutrinos during their voyage.

But, after analysing the results of a year’s worth of data, the researchers found no feature suggesting the existence of sterile neutrinos around 1 eV. This is line with results from the European Space Agency’s Planck observatory, which concluded from cosmological evidence that there should only be three families of neutrinos in that mass range. “I hope that with our result and with the Planck result we are slowly walking our way back from this story,” says Halzen. The IceCube team are still taking data in their sterile neutrino hunt, but don’t expect their results to change, he adds.

Despite this null result, there is still a possibility that sterile neutrinos exist, but not at the mass predicted.

The rupture of a drum at a nuclear waste site in New Mexico has shut down a neutrino experiment.

The rupture of a drum at a nuclear waste site in New Mexico has shut down a neutrino experiment.

This article, from Nature, focuses on the harm done to the science experiment, which is considerable and very unfortunate. However, scroll to the end of the article to learn a little about the drum rupture, which has serious implications for the storage of nuclear waste anywhere.

Chinese physicists have discovered a key measurement that helps explain why and how can neutrinos magically oscillate between three different states.

Chinese physicists have discovered a key measurement that helps explain why and how neutrinos can magically oscillate between three different states. Moreover, the data

implies that there could be a slight asymmetry between neutrinos and antineutrinos—called CP violation—a slight asymmetry that might help explain why the universe evolved to contain so much matter and so little antimatter.

The CERN experiment that appeared to see faster-than-light neutrinos has repeated its results, except that not everyone on the team agrees

The uncertainty of science: The CERN experiment that appeared to see faster-than-light neutrinos has repeated its results, except that not everyone on the team agrees.

The new tests, completed 6 November, did away with the statistical analysis by splitting each pulse into bunches just 1- to 2-nanoseconds long, allowing each neutrino detected at Gran Sasso to be tied to a particular bunch produced at CERN. These tests were carried out over 10 days and provided 20 events. The researchers confirmed that the neutrinos arrived 60 nanoseconds early, with an uncertainty of about 10 nanoseconds, comparable to that of the initial result. The collaboration has also checked its original statistical analysis, but today’s decision to submit the results to a journal was not unanimous. “About four people” among the group of around 15 who did not sign the preprint have signed the journal submission, according to a source within the collaboration, while “four new people” have decided not to sign. That leaves the number of dissenters at about 15, compared with about 180 who did sign the journal submission.

Scientist proposes that the superluminal neutrinos are merely measuring the true speed of light

On Thursday physicist Susan Gardner of the University of Kentucky proposed in a preprint on the Los Alamos astro-ph website that the neutrinos measured at CERN that appeared to be going faster than light were merely giving us a much more accurate measure of the speed of light.

This is only one of a plethora of papers published this last week on astro-ph discussing and attacking the CERN neutrino results. I expect the scientists will solve this mystery before too long.

Faster than light?

Can neutrinos travel faster than light? After three years of gathering data, an experiment at CERN says they do, though by only a tiny amount.

[Physicist Antonio] Ereditato says that he is confident enough in the new result to make it public. The researchers claim to have measured the 730-kilometre trip between CERN and its detector to within 20 centimetres. They can measure the time of the trip to within 10 nanoseconds, and they have seen the effect in more than 16,000 events measured over the past two years. Given all this, they believe the result has a significance of six-sigma — the physicists’ way of saying it is certainly correct.

You can download and read a preprint of their paper here.

What I find intriguing about this result, other than its exciting groundbreaking possibilities, is how it illustrates sharply the contrast between normal and healthy science, and the sad and sick state of the field of climate science.
» Read more

An international team of scientists said on Thursday they had recorded sub-atomic particles traveling faster than light

An international team of scientists said on Thursday they had recorded sub-atomic particles that travel faster than light.

A total of 15,000 beams of neutrinos — tiny particles that pervade the cosmos — were fired over a period of 3 years from CERN toward Gran Sasso 730 (500 miles) km away, where they were picked up by giant detectors. Light would have covered the distance in around 2.4 thousandths of a second, but the neutrinos took 60 nanoseconds — or 60 billionths of a second — less than light beams would have taken. “It is a tiny difference,” said Ereditato, who also works at Berne University in Switzerland, “but conceptually it is incredibly important. The finding is so startling that, for the moment, everybody should be very prudent.”

Fermilab confirms Japanese particle physics results that could explain lack of antimatter in the universe

Fermilab has confirmed the Japanese particle physics experiment from two weeks ago suggesting that muon neutrinos can morph into electron neutrinos.

The results of these two experiments could have implications for our understanding of the role that neutrinos may have played in the evolution of the universe. If muon neutrinos transform into electron neutrinos, neutrinos could be the reason that the big bang produced more matter than antimatter, leading to the universe as it exists today