Tohoku Univ. scientists find new neutrino

Yomiuri Shimbun ^ | 2002-12-07

[Lessismore]

An international team researching particle physics at Tohoku University has observed a new kind of neutrino--one of the building blocks of the universe--and almost certainly confirmed that the particles have mass, it was learned Tuesday.

The neutrinos are different from the type detected by Tokyo University professor emeritus and Nobel laureate Masatoshi Koshiba and others, according to the researchers.

Working at Tokohu University's Research Center for Neutrino Science neutrino observation facility, the researchers detected antielectron neutrinos, which are the antimatter of one of three types of neutrinos.

They almost certainly confirmed that the neutrinos they detected had mass--just as the team of which Koshiba was a member did, the researchers said.

The findings are significant because under the so-called Standard Model of conventional elementary particles it has been postulated that neutrinos have no mass.

In 1998, the Tokyo University research group almost certainly confirmed that another kind of neutrinos, muon neutrinos, have mass as they interact gravitationally with other particles.

If it is confirmed that neutrinos do have mass, it will necessitate the rewriting of conventional theories about the components and origin of the universe, according to experts.

The latest findings back up those of the Tokyo University team, and place Japan at the forefront of neutrino studies, they said.

The team, which comprised researchers from Stanford University and other institutes around the world, began observing the neutrinos in January with a neutrino detection system called KamLAND (Kamioka Liquid Scintillator Anti-Neutrino Detector) of Tohoku University's neutrino science research center.

The center is next to Tokyo University's neutrino-detecting facility, Super-Kamiokande, in Kamiokacho, Gifu Prefecture.

[Fish out of Water]

bump

[billorites]

"The findings are significant because under the so-called Standard Model of conventional elementary particles it has been postulated that neutrinos have no mass. "

Great. That means they can be taxed as personal property.

[knighthawk]

A new neutrino!

[Willie Green]

The team, which comprised researchers from Stanford University and other institutes around the world, began observing the neutrinos in January with a neutrino detection system called KamLAND (Kamioka Liquid Scintillator Anti-Neutrino Detector) of Tohoku University's neutrino science research center.

The cool thing about Kamioka Liquid Scintillator Anti-Neutrino Detectors is that they can be recalibrated for use as a long range Godzilla warning device.

[onedoug]

Funny, God.

[struggle]

Tohoku: The West Virginia of Japan.

[El Gato]

A new neutrino!

Sort of. Positron (anti electron) neutrinos are a part of the "standard model". This is just experiement confirming that they exist, and then throwning a part of the theory into a cocked by finding that they have (rest) mass, which the "Standard Model" says neutrinos, any kind and there are 6 of them counting the anti-particles) shouldn't have mass. Interesting times for the physicists.

[TopQuark]

I wonder what that will do to the quark model.

Am I in trouble?

[TopQuark]

Interesting times... My very existence is in danger, and you call that interesting?

[BenR2]

Ahh, yess. Good old Tohoku. Land of onsen and nebuta!

[Gary Boldwater]

"If it is confirmed that neutrinos do have mass, it will necessitate the rewriting of conventional theories about the components and origin of the universe, according to experts."

If so, does this mean current theories are wrong?

[longshadow]

Holy anti-neutrino with mass, Batman!

[general_re]

Tohoku Univ. scientists find new neutrino

Was it lost? I sometimes find my keys under the couch cushions - did they look there?

[razorback-bert]

Glad they found a new neutrino, my old one was getting worn.

[mjp]

it will necessitate the rewriting of conventional theories about the components and origin of the universe, according to experts.

Does this mean there will be an omega point?

[Doctor Stochastic]

The suggestion that neutrinos have mass has been around since the "neutrino" problem with the sun was found. There were only 1/3 as many neutrinos as expected. This could be explained if neutrinos had mass and thus could switch type.

[Stirner]

Armchair physics is such fun! I remember speculating about 10 years ago with someone about neutrinos having mass, and his response was that neutrinos move at the speed of light and that the theory of relativity implies that no massive object can achieve that speed. My thought was that neutrinos with slight mass could account for the "missing matter" (the fact that galaxies interact with each other gravitationally as if they had much greater mass than we can observe in them). But my friend's comment about relativity shut me up. However, maybe neutrinos travel at slightly less than the speed of light, or the theory of relativity needs revision.

[Physicist]

The headline is so misleading as to be wrong. This is not a new kind of neutrino, but the antimatter counterpart to the same old neutrinos that are produced by the sun or by nuclear reactors. This discovery is perfectly in step with the Standard Model of Particle Physics.

Assuming that the reporter got the story right, which is highly uncertain, the significance of this finding has to do with the spin structure of the neutrino. There have been two possible candidates for this structure since the 1930's: the Dirac neutrino model allows for both neutrinos and antineutrinos, while the Majorana neutrino model states that neutrinos are their own antiparticles.

If neutrinos have no mass, the two models give exactly the same predictions for the behavior of neutrinos. [Geek alert: this is because two components of the 4-component spinor used to describe the neutrino spin are projected out at the speed of light; both Dirac-type and Majorana-type neutrinos end up with the same 2-component spinor.]

But neutrinos do have mass, as was proved conclusively by the Sudbury Neutrino Observatory last year. If the conclusion of this article is correct, and antineutrinos are not simply neutrinos with the opposite "handedness" (a quantity about which two observers in different frames might disagree), then it seems that the Majorana picture has been ruled out. The sand has been shifted away, and we may now build our house upon Dirac.

[PatrickHenry]

Probably this is a duplicate ping for some of you, but that's how it goes. Big neutrino news!

[This ping list for the evolution -- not creationism -- side of evolution threads, and sometimes (as now) for other science topics. If you want to be included, or dropped, let me know.]