Tiny Particle With No Charge Discovered 280
ZonkerWilliam writes to mention PhysOrg is reporting that a tiny particle with no charge, called an 'axion' has been discovered. From the article: "The finding caps nearly three decades of research both by Piyare Jain, Ph.D., UB professor emeritus in the Department of Physics and lead investigator on the research, who works independently -- an anomaly in the field -- and by large groups of well-funded physicists who have, for three decades, unsuccessfully sought the recreation and detection of axions in the laboratory, using high-energy particle accelerators."
and it means... (Score:4, Informative)
Wiki (Score:5, Informative)
Re:Detected... (Score:5, Informative)
"They didn't know how to handle the detector for short-lived particles," Jain said. "I knew that for this very short-lived particle -- 10-13 seconds -- the detector must be placed very near the interaction point where the collision between the projectile beam and the target takes place so that the produced particle doesn't run away too far; if it does, it will decay quickly and it will be completely missed. That is what happened in most of the unsuccessful experiments." Instead, Jain used a visual detector, made of three-dimensional photographic emulsions, which act as both target and detector and that therefore can detect very short-lived particles, such as the axion. However, use of such a detector is so specialized that to be successful, it requires intensive training and experience. In the 1950s, Jain was trained to use this type of detector by its developer, the Nobel laureate, British physicist Cecil F. Powell. Jain has used it throughout his career to successfully detect other exotic
Re:Detected... (Score:3, Informative)
Think of it like those high speed film clips of a bullet going through a block of ballistics gel. The particle hits the emulsion and leaves a detectable wake.
Re:Tiny Particle with no charge? (Score:5, Informative)
Re:Not news (Score:3, Informative)
No, neutrons have a neutral charge -- that is, that their net charge is neither positive (+) nor negative (-). But they have a charge. Protons have a net positive charge, electrons have a net negative charge and axions have absolutely no charge at all.
Re:Long Lived Axions (Score:4, Informative)
Most models for axions are much lighter and have much weaker interactions, giving them much longer lifespans. That's what's being described in the article you cite. An axion with those properties would be an ideal candidate for dark matter - tons of them would fill the universe, and they'd be nearly undetectable due to their weak interactions.
Most searches for axions focus on the longer-lived possibilities for this reason, so far with no success. I'm intrigued if this claim is true, but I'll wait to see what other physicists think.
Re:This is a big deal (Score:5, Informative)
that is in the plancks (need a atom smasher as big as the solar system) mass range. String theory does have axions in it as well
as stacks of light neutral particles called moduli. The article didn't say how they knew or why they thought that particle was an
axion. The experiment found at light neutral particle with mass ~19 Mev (or maybe 7 Mev) that decays to electron positron pairs, they didn't say the had a spin measurement, if its not spin 0 with negative parity its definitely not an axion. Another experiment (PVLAS) last year found evidence a particle with mass in the milliEv range, that fits more with an axion. So maybe this is something
else.
Re:Long Lived Axions (Score:2, Informative)
Re:Detected... (Score:2, Informative)
I guess it doesn't have anything to do with the charged particles that those atoms are made out of, and that they wouldn't use the electromagnetic force to interact with each other.
There surely is stupidity here, but I'd look more to your own ignorance than with the grandparent's commentary.
Re:Detected... (Score:5, Informative)
And the Universe is powered by stupidity. The wake of a bullet going through ballistics gel is caused by the shockwave of the bullet's impact with the surface of the gel; a bullet is not a charged particle, nor magnetic, and it's way to big to create the ionization effects that traditional particle detectors use. I don't know how it is possible that, not only could say that a bullet causes a wake due to electromagnetic force, but that a mod actually believed that bullshit.
I hope this is a good learning experience for you and I hope that you don't recklessly call other posters stupid next time.
"Physics today" covered axion searches in August (Score:2, Informative)
Re:Detected... (Score:2, Informative)
Re:Detected... (Score:4, Informative)
The point that I was trying to make is that a zero charge particle doesn't interact electromagnetically so we can't use conceptual examples that involve the electromagnetic force regardless of how trivial to describe it. There do exist many particles that do interact electromagnetically and you could say they travel through a medium (such as a bubble chamber [wikipedia.org]) like a bullet through a ballistics jel. Heck, I've even seen the extreme examples of this where I was able to observe Cherenkov radiation [wikipedia.org] from a nuclear reactor's fuel elements (where a charged particle moves faster than the speed of light in that medium producing a really pretty blue light).
But the axion itself does not interact electromagnetically so by itself it does not produce a wake. The electron and positron produced will certainly produce wakes, but that point needs to be pointed out explicitly. The axion is not detected directly from electromagnetic interactions, only its decay products are (which are released symmetrically around the axis of the axion).
Re:What did the bartender say to the axion? (Score:4, Informative)
Re:This is a big deal (Score:4, Informative)
Re:Cool that he had to use an analog detector (Score:4, Informative)
Re:This is a big deal (Score:3, Informative)
Actually sting theory predicts axions. As per Wikipedia on Axion [wikipedia.org]: It should be noted that the existence of axions is also a necessary component of string theory. But that is a fairly weak prediction of string theory, as other models also predict the axion.
String theory is stuck in a bizarre limbo in that the interesting predictions it does make involve math that's so hard that we can't actually understand what the predictions are.
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