Science & Technology - Posted by Dan Stober-Stanford on Tuesday, August 24, 2010 11:21 - 6 Comments 
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(1 votes, average: 5.00 out of 5) Loading ...The search for sun’s mystery particle
When researchers found an unusual linkage between solar flares and the inner life of radioactive elements on Earth, it touched off a scientific detective investigation that could end up protecting the lives of space-walking astronauts and maybe rewriting some of the assumptions of physics. This image shows several flares and their associated waves across the sun. (Credit: NASA/GSFC/AIA)
STANFORD (US)—Is it possible that the radioactive decay of some elements sitting quietly in laboratories on Earth could be influenced by activities inside the sun, 93 million miles away.
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The text of this article by Futurity is licensed under a Creative Commons Attribution-No Derivatives License.
Researchers from Stanford University and Purdue University believe it is. But their explanation of how it happens opens the door to yet another mystery.
There is even an outside chance that this unexpected effect is brought about by a previously unknown particle emitted by the sun. “That would be truly remarkable,” says Peter Sturrock, Stanford professor emeritus of applied physics and an expert on the inner workings of the sun.
The story begins, in a sense, in classrooms around the world, where students are taught that the rate of decay of a specific radioactive material is a constant. This concept is relied upon, for example, when anthropologists use carbon-14 to date ancient artifacts and when doctors determine the proper dose of radioactivity to treat a cancer patient.
But that assumption was challenged in an unexpected way by a group of researchers from Purdue who at the time were more interested in random numbers than nuclear decay. (Scientists use long strings of random numbers for a variety of calculations, but they are difficult to produce, since the process used to produce the numbers has an influence on the outcome.)
Ephraim Fischbach, a physics professor at Purdue, was looking into the rate of radioactive decay of several isotopes as a possible source of random numbers generated without any human input.
A lump of radioactive cesium-137, for example, may decay at a steady rate overall, but individual atoms within the lump will decay in an unpredictable, random pattern. Thus the timing of the random ticks of a Geiger counter placed near the cesium might be used to generate random numbers.
As the researchers pored through published data on specific isotopes, they found disagreement in the measured decay rates—odd for supposed physical constants.
Checking data collected at Brookhaven National Laboratory on Long Island and the Federal Physical and Technical Institute in Germany, they came across something even more surprising: Long-term observation of the decay rate of silicon-32 and radium-226 seemed to show a small seasonal variation. The decay rate was ever so slightly faster in winter than in summer.
Was this fluctuation real, or was it merely a glitch in the equipment used to measure the decay, induced by the change of seasons, with the accompanying changes in temperature and humidity?
“Everyone thought it must be due to experimental mistakes, because we’re all brought up to believe that decay rates are constant,” Sturrock says.
On Dec 13, 2006, the sun itself provided a crucial clue, when a solar flare sent a stream of particles and radiation toward Earth. Purdue nuclear engineer Jere Jenkins, while measuring the decay rate of manganese-54, a short-lived isotope used in medical diagnostics, noticed that the rate dropped slightly during the flare, a decrease that started about a day and a half before the flare.
If this apparent relationship between flares and decay rates proves true, it could lead to a method of predicting solar flares prior to their occurrence, which could help prevent damage to satellites and electric grids, as well as save the lives of astronauts in space.
The decay-rate aberrations that Jenkins noticed occurred during the middle of the night in Indiana—meaning that something produced by the sun had traveled all the way through the Earth to reach Jenkins’ detectors. What could the flare send forth that could have such an effect?
Jenkins and Fischbach guessed that the culprits in this bit of decay-rate mischief were probably solar neutrinos, the almost weightless particles famous for flying at the speed of light through the physical world—humans, rocks, oceans, or planets—with virtually no interaction with anything.
Then, in a series of papers published in Astroparticle Physics, Nuclear Instruments and Methods in Physics Research, and Space Science Reviews, Jenkins, Fischbach, and colleagues showed that the observed variations in decay rates were highly unlikely to have come from environmental influences on the detection systems.
Their findings strengthened the argument that the strange swings in decay rates were caused by neutrinos from the sun. The swings seemed to be in synch with the Earth’s elliptical orbit, with the decay rates oscillating as the Earth came closer to the sun (where it would be exposed to more neutrinos) and then moving away.
So there was good reason to suspect the sun, but could it be proved?
Enter Peter Sturrock, Stanford professor emeritus of applied physics and an expert on the inner workings of the sun. While on a visit to the National Solar Observatory in Arizona, Sturrock was handed copies of the scientific journal articles written by the Purdue team.
Sturrock knew from long experience that the intensity of the barrage of neutrinos the sun continuously sends racing toward Earth varies on a regular basis as the sun itself revolves and shows a different face, like a slower version of the revolving light on a police car.
His advice: Look for evidence that the changes in radioactive decay on Earth vary with the rotation of the sun. “That’s what I suggested. And that’s what we have done.”
Going back to take another look at the decay data from the Brookhaven lab, the researchers found a recurring pattern of 33 days. It was a bit of a surprise, given that most solar observations show a pattern of about 28 days—the rotation rate of the surface of the sun.
The explanation? The core of the sun—where nuclear reactions produce neutrinos—apparently spins more slowly than the surface we see. “It may seem counter-intuitive, but it looks as if the core rotates more slowly than the rest of the sun,” Sturrock says.
All of the evidence points toward a conclusion that the sun is “communicating” with radioactive isotopes on Earth, says Fischbach.
But there’s one rather large question left unanswered. No one knows how neutrinos could interact with radioactive materials to change their rate of decay.
“It doesn’t make sense according to conventional ideas,” Fischbach says. Jenkins whimsically adds, “What we’re suggesting is that something that doesn’t really interact with anything is changing something that can’t be changed.”
“It’s an effect that no one yet understands,” agrees Sturrock. “Theorists are starting to say, ‘What’s going on?’ But that’s what the evidence points to. It’s a challenge for the physicists and a challenge for the solar people too.”
If the mystery particle is not a neutrino, “It would have to be something we don’t know about, an unknown particle that is also emitted by the sun and has this effect, and that would be even more remarkable,” Sturrock says.
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6 Comments
The fact some of the effects of solar flares appear to appear before the flare itself may be due to slow passage from the center of the sun or indicate an exception to the “nothing faster than light” rule. One explanation gives information about the center of the sun, the other gives theoretical physicists headaches and opportunities.
IANAP but I would venture the opinion that a) solar flares begin as a disturbance near the sun’s core that takes 1.0-1.5 days to reach the surface, and b) the constant flow of the neutrinos, even though typically non-interacting with matter, leave less surrounding space for protons or neutrons or energy or however the decay manifests.
Next step in trying to identify the cause, is if all known heavy isotopes behave the same way.
The Razor
One can’t help but wonder what this means for radiometric dating techniques.
Jimmy James
The amount of deviation from currently measured half lives indicate that any change in radiometric carbon dating would be inconsequential. The decay rate oscillates as we revolve around the sun, so the current accepted half lives are more of an average with a small deviation, so any correction in say C-14 dating would be like a few minutes every thousand years.
Screeching Demon
After reading this article a few days ago, I had an idea pop into my head this morning. If scientists are able to capture and reproduce this “mystery particle”, and it slows atomic decay, then it would seem with extensive research we could build a device that renders nuclear weapons useless. The “mystery particle” would have to be mass produced and directed almost as an intense beam. Using that “beam”, it makes sense to me that once this beam comes in contact with radioactive isotopes, if it is concentrated enough then perhaps it could immensely slow down or perhaps even stop nuclear fission. I do realize that our ability to do something like this may be several years or even decades down the road, but perhaps this will catch someone’s eye who has the equipment to do such research. I myself wonder if these particles may be the long sought -gravitons- which may have interactions at the atomic or subatomic level. Then again, it could be a new form of the strong or weak force only with a much longer reach. Who knows? Anyway, I just want to see this become more of a safety device for nuclear power plants if we decide to keep them, and certainly be formed into an anti-weapon capable of stopping nuclear bombs from exploding. Does anyone else have similar ideas? Please reply or feel free to email me!
These are the voyages of the starship Solar Neutrino. Her billion years mission, react with the universe in strange and wonderful ways. And force earthlings back to the drawing board.