Scientists find link between the sun and radioactive decay

[LionElJonson]

http://news.stanford.edu/news/2010/augu ... 82310.html

The strange case of solar flares and radioactive elements

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.

BY DAN STOBER

It's a mystery that presented itself unexpectedly: The radioactive decay of some elements sitting quietly in laboratories on Earth seemed to be influenced by activities inside the sun, 93 million miles away.

Is this possible?

Researchers from Stanford 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," said 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.

Random numbers

But that assumption was challenged in an unexpected way by a group of researchers from Purdue University 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 said.

The sun speaks

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 almost 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 their colleagues showed that the observed variations in decay rates were highly unlikely to have come from environmental influences on the detection systems.

Reason for suspicion

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 researchers.

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 to Purdue: 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."

A surprise

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 said.

All of the evidence points toward a conclusion that the sun is "communicating" with radioactive isotopes on Earth, said 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 said. Jenkins whimsically added, "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," agreed 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 said.

Quite interesting, if it turns out to be true; I wonder what the implications for nuclear physics would be.

[CaptJodan]

Interesting. Now we cue YECs crying that they were right all along, radiometric dating is a fraud because it's not even constant.

[Sarevok]

^^

Negative. The effect even if it is conclusively proven is so negligible it has not been observed in a century of intense research with radioactivity. Any errors in calculations made regarding age of the earths crust must be very minute.

[Surlethe]

Holy christ. Can anybody get their hands on the articles themselves?

[The Vortex Empire]

I expect to hear creationists claiming victory with this, despite the implications of this discovery only meaning that fossil A might be from 975,000 years ago rather than 1,000,000 years ago. But we can't expect them to use their brains, can we?

[Mayabird]

I did a quick search for the articles to see if I could get them for free (no such luck and I'm not paying $31.50 each when someone might be able to get it elsewhere) but I did find some titles so people at universities might be able to access them:

Perturbation of nuclear decay rates during the solar flare of 2006 December 13
Jere H. Jenkins and Ephraim Fischbach
Astroparticle Physics
Volume 31, Issue 6, July 2009, Pages 407-411
doi:10.1016/j.astropartphys.2009.04.005

Evidence of correlations between nuclear decay rates and Earth–Sun distance
Jere H. Jenkins, Ephraim Fischbach, John B. Bunchera, John T. Gruenwalda, Dennis E. Krausea, and Joshua J. Mattes
Astroparticle Physics
Volume 32, Issue 1, August 2009, Pages 42-46
doi:10.1016/j.astropartphys.2009.05.004

There were more, but Jere Jenkins and Ephraim Fischbach have their names on pretty much all of the related articles and follow-up research (understandable since it's so recent). The only one I found that didn't was this:

No evidence for antineutrinos significantly influencing exponential β+ decay
R.J. de Meijera, M. Blaauw and F.D. Smit
Applied Radiation and Isotopes
doi:10.1016/j.apradiso.2010.08.002

which seems to come to a different conclusion, but again, it's a bit pricey and I can only see the abstract.

So, can anyone at a university access them for free? What do they say?

[phongn]

Holy christ. Can anybody get their hands on the articles themselves?

Evidence of correlations between nuclear decay rates and Earth–Sun distance, DOI: 10.1016/j.astropartphys.2009.05.004

Analysis of environmental influences in nuclear half-life measurements exhibiting time-dependent decay rates, DOI: 10.1016/j.nima.2010.03.129

Perturbation of nuclear decay rates during the solar flare of 2006 December 13, DOI: 10.1016/j.astropartphys.2009.04.005

[phongn]

So, can anyone at a university access them for free? What do they say?

As we noted in the Introduction, there are at present two competing general explanations for the apparent fluctuations observed in the BNL and PTB data: (a) they arise from the responses of the respective detector systems to seasonal variations in temperature, pressure and humidity, and possibly other factors such as radon buildup, and (b) the fluctuations arise from the decay process itself, due to some as yet unknown influence possibly originating from the Sun. By modeling the respective detector systems in detail, we have shown here that alternative (a) is an unlikely explanation for the observed BNL and PTB data, and hence by implication alternative (b) is more likely to be correct. The resulting inference, that nuclear decay rates are being directly influenced by solar activity, is further supported by our analysis of 54Mn decay data acquired during the solar flare of 2006 December 13, which we have also analyzed. Our conclusion that the dip in the 54Mn data, which was coincident in time with the flare, was not likely attributable to changes in the cosmic ray flux during the flare, further strengthens the case that nuclear decays are being directly affected by solar activity. This inference can evidently be checked in a variety of experiments such as those described on Ref. [3], some of which are already in progress.

Full text of the article not posted for copyright reasons.

[Dooey Jo]

Isn't it fairly well-known that neutrinos can interact with nucleons, at least by changing a proton into a neutron, or causing fission?

[starslayer]

So far I've only read the last two papers Mayabird posted, but if the effect Jenkins and Fischbach described is in fact real, it reveals some interesting facts about radioactive decay, neutrinos, and solar dynamics:

-Assuming that both papers are on the right track, Meijera, et al. note that this would mean the effect of antineutrinos on β+ decay (positron emission) is very different from that of electron neutrinos on β- decay (electron emission). Namely, that antineutrinos don't have any effect whatever on how protons decay, but that neutrinos can and do influence how neutrons decay.
-Following on from Jenkins and Fischbach's work, it would mean that solar storms are influenced by fluctuations in fusion rates in the Sun's core, which is all kinds of weird, because that is not where the Sun's field is generated, as the core is radiative, not convective and thus does not support the large scale movement of plasma necessary to drive a magnetic dynamo. Rather, the field originates in the convective zone, which comprises most of the Sun's envelope.
-It would mean that neutrinos are almost certainly not their own antiparticles, or that the spin of a neutrino has large effects on what interactions it can participate in.*

I'm still not sold Jenkins and Fischbach's work, but they do seem to have controlled for various outside influences that could upset their conclusion. I do however think that further experimentation based on the decay of Mn-54 or other such short-lived isotopes is warranted in the next 10 years, as solar maximum comes around again. If no effects are seen then, it would mean something anomalous occurred in Jenkins and Fischbach's apparatus in 2006.

Isn't it fairly well-known that neutrinos can interact with nucleons, at least by changing a proton into a neutron, or causing fission?

Yes, but Jenkins and Fischbach's data shows a dip in the decay rate during significant solar storms, not an increase. One would expect the opposite to be true if neutrino collisions were responsible for beta decay (they're not), and such an effect would be much, much smaller than than seen by Jenkins and Fischbach.

*DISCLAIMER: I am not an expert on particle physics by any means; my area of study is optics and astronomical instrumentation, so take this especially with a grain of salt.

[Dooey Jo]

Isn't it fairly well-known that neutrinos can interact with nucleons, at least by changing a proton into a neutron, or causing fission?

Yes, but Jenkins and Fischbach's data shows a dip in the decay rate during significant solar storms, not an increase. One would expect the opposite to be true if neutrino collisions were responsible for beta decay (they're not), and such an effect would be much, much smaller than than seen by Jenkins and Fischbach.

Well that's unless the neutrino flux also decreased for some reason during the solar storm. Solar storms aren't supposed to create very many neutrinos compared to the reactions in the Sun's core anyway.

In any case, the seasonal variation seems easy enough to test.

[starslayer]

Well that's unless the neutrino flux also decreased for some reason during the solar storm. Solar storms aren't supposed to create very many neutrinos compared to the reactions in the Sun's core anyway.

No, they don't; no real change in the neutrino rate has ever been measured due to solar storms, except in this data set, which is what makes this so damned weird. Given that they also say that they've measured dips in the decay rate due to seasonal changes, and it was higher at aphelion (at least, IIRC; I haven't gone back and checked since earlier this afternoon), a dip would indicate increased neutrino flux. Even if the opposite is true, that a higher neutrino flux increases the decay rate, we still come back to the conclusion that fluctuations in the Sun's core affect solar storms, as the core is the only significant source of solar neutrinos.

[Simon_Jester]

-It would mean that neutrinos are almost certainly not their own antiparticles, or that the spin of a neutrino has large effects on what interactions it can participate in.*

This much we already know. The difference between neutrinos and antineutrinos was nailed down even before the first observation of the beasts and proved to be spot on, andd the second... well, it's called the "law of conservation of angular momentum."

[Kuroneko]

A preprint of the Earth-Sun paper is available at [arXiv:0808.3283v1]. It's worth noting that:
-- Probably the study least environmentally-dependent study decay rates, or at least one in best position to detect specifically solar effects, was based on the plutonium on the Cassini spacecraft, and found no deviation from the normally expected exponential decay [arXiv:0809.4248v1]. Another study based on numerous isotopes was published in the same journal several months before that particular Jenkins & Fischbach paper, and similarly found no evidence for the "Jenkins hypothesis" of ~1/R² Earth-Sun distance contribution to decay rates [arXiv:0810.3265v1].
-- Jenkins & Fischbach's data is decomposed into the normally expected decay, a seasonal adjustment, and a third unexplained factor. You can see it pretty clearly in Fig. 2 [arXiv:0808.3283v1] [large png], where there are large deviations from the claimed seasonal term.

Thus, the measured decay rate is the exponential rate, a seasonal shift in decay rate, and some other stuff skewing the measurement. If the third term was negligible compared to the other two, or if there was an additional explanation for it, then there would be evidence that there is a seasonal change in the decay rate. But it's not negligible and no explanation for provided, i.e., all of the deviation could be to the unexplained factor skewing the measurement, with no actual shift in decay rate. And I'd bet that this factor eventually turns out to be calibration errors, which could easily introduce seasonal shifts in measurements without a corresponding change in the decay rate, because actual detectors are not free from environmental effects.

The bottom line is that there are numerous studies both on decay rate variations in general and on the Jenkins hypothesis specifically, and only ones done by Jenkins et al. actually find such an effect... and the logic is somewhat dubious even there.

[wautd]

I expect to hear creationists claiming victory with this, despite the implications of this discovery only meaning that fossil A might be from 975,000 years ago rather than 1,000,000 years ago. But we can't expect them to use their brains, can we?

They did the same when they found the speed of light can be altered/slowed. Offcourse, this would imply that the visible universe might be slightly older, so I guess this finding is evening things out