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The Strange Case of Solar Flares and Radioactive Decay Rates 408

Posted by Soulskill
from the cool-science dept.
DarkKnightRadick writes "Current models for radioactive decay have been challenged by, of all sources, the sun. According to the article, '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.' This is important because the rate of decay is very important not just for antique dating, but also for cancer treatment, time keeping, and the generation of random numbers. This isn't a one time measurement, either. '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.'"
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The Strange Case of Solar Flares and Radioactive Decay Rates

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  • by Tenek (738297) on Tuesday August 24, 2010 @12:00AM (#33350704)
    No, this does not get you down to a 6000-year old Earth. Sorry.
    • If anything, it sounds like our estimates of the Earth's age may be too young, not too old. Pending, of course, confirmation that the results aren't the result of an error in statistical analysis.

      • Re: (Score:3, Informative)

        by mpe (36238)
        If anything, it sounds like our estimates of the Earth's age may be too young, not too old.

        Not just the Earth, but anything where radioactive decay is used as the basis for working out age. Things get even more troublesome if this effect is not uniform across radio isotopes.
    • by postermmxvicom (1130737) on Tuesday August 24, 2010 @11:41AM (#33356092)
      Hello. I am a Bible believing slashdotter. My college degree is in theoretical physics at a state university. My beliefs have never caused a serious permanent conflict with my education. Many people here would tell me that it should. They bash and mock young-earthers or any number of beliefs which *they* see as irreconcilable with science. Just a couple of things I want to point out:

      1) Many *many* scientific advances have been made by deeply religious men and funded by a church. This is true historically and into our modern era. If you want a citation, use google.

      2) Yes, there are religious people who do not understand science and say things that make us science folk cringe. That is not an excuse to bash religion or faith. That will not endear you to anyone or further scientific education. Remember there are also loony unscientific atheists, agnostics, as well as people of any other philosophical or religious persuasion. Pseudo-science is *not* the exclusive domain of the religious.

      Do you want the general public to treat scientist and nerds the way some of you treat religious people? "Hey, a scientist sold me these brilliant pebbles [machinadynamica.com]. It turns out it's a crock - all scientist must be idiots! After all, this guy claiming to be a scientist is." We could all list countless failures by honest and dishonest men of science. Would you like the general public to lump you all together with ridicule and discard any science that has ever been touched or used by one of these men? They would throw out all of science! I am asking for you to be kind and understanding. It is possible to point out weaknesses in someone's theory without scorn and ridicule and without trying to trash their beliefs because of it. That will only alienate most people.

      Defending an idea with bad science does not make the idea wrong - only the defense.
  • Lets hope nobody identifies Plutonium-186 [wikipedia.org]

  • or proximity to the sun? could the amount of ambient energy have an effect on decay rates? Ice melts faster in the summer than in winter, or does it? observed decay is relative to an average state.... balanced equations and all that stuff I tried to forget from school come back....

    • by trip11 (160832) on Tuesday August 24, 2010 @12:11AM (#33350768) Homepage
      I read the article (yes yes I know). But in summary, your hypothesis (temperature fluctations0 was what everyone thought, but the groundbreaking bit was that they did an experiment that provides a LOT of evidence to the contrary.

      The sun has a cycle of it's own (about 1 month). They did a much more accurate study and found the decay rate is tightly correlated to the sun's cycle.

      Longer version:
      The theory now is that it has to do with the neutrino flux. As we move further from the sun the flux goes down by 1/R^2. We saw that fluctuation first. But the neutrino flux also varies with the solar cycle which is independent of the earth's temperature.

      This is very very cool experimental physics. Kudo's to them!

      • Re: (Score:3, Interesting)

        by dakameleon (1126377)

        There's another possible simple test: use the southern hemisphere. If it goes down in winter in the southern hemisphere at the same time as going up in the northern, that's a whole different data point.

        • by camperdave (969942) on Tuesday August 24, 2010 @01:14AM (#33351162) Journal
          Neutrino density is not going to vary a lot by hemisphere because the planet is fairly transparent to neutrinos. However, the Earth as a whole (including the southern hemisphere) is some 3% closer to the sun during the winter (January) than during the summer.
          • by realityimpaired (1668397) on Tuesday August 24, 2010 @07:53AM (#33353234)

            I'm pretty sure that's exactly why darkmeleon suggested doing the experiment in the southern hemisphere: it's a great way to either prove or disprove those saying that temperature variation is what's causing the change in measured decay rates: if it's caused by the weather's effect on the equipment, then the effect should be out of phase in the southern hemisphere than the northern. If, on the other hand, the increase/decrease happens in the same months, then it confirms that it's the proximity to the sun that's causing it.

        • by ComaVN (325750)

          Or... use a termostat in the lab?

  • by MMatessa (673870) on Tuesday August 24, 2010 @12:06AM (#33350752)
    One way to double-check the seasonal variation effect is to look at the output level on radioisotope power sources in spacecraft. Cooper (2008) found no relationship between radioactive decay and distance to the sun [astroengine.com].
    • Cassini also has the advantage of little if any other material around it to have an adverse effect on measurement, measured decay could be affected by surroundings.
      I'm not even certain how you would go about having a closed system to measure, you can know a speed or a location but.....

      • Re: (Score:3, Interesting)

        by c0lo (1497653)

        Cassini also has the advantage of little if any other material around it to have an adverse effect on measurement, measured decay could be affected by surroundings.

        Even more than this.
        What is the precision one can trust for Cassini's measurements? How small is the seasonal variation in Earth conditions? How the two compares?

    • by Sarten-X (1102295) on Tuesday August 24, 2010 @12:27AM (#33350852) Homepage
      Not quite. Cooper found no variation with regards to one specific isotope of plutonium. There could be a different mechanism at work to cause plutonium's decay, or multiple mechanisms. Maybe neutrinos are involved. Maybe not. The ideas presented in TFA are theories, which will (hopefully) eventually lead to a testable hypothesis.A single contradictory result, without explanation, should not be enough to halt research in the field.
    • by c0lo (1497653) on Tuesday August 24, 2010 @12:41AM (#33350930)
      Facts:
      1. long-term observation of the decay rate of silicon-32 and radium-226 show a small seasonal variation (on Earth conditions? With lab equipment that can be subject to other seasonal variation?)
      2. radioactive decay of the Pu-238 isotope is insensitive (within the experimental precision) to distance to the Sun

      What valid conclusion can one derive from the above facts? In my opinion, exactly one, which is more research is necessary.

      • Re: (Score:3, Insightful)

        by ColdWetDog (752185)

        What valid conclusion can one derive from the above facts? In my opinion, exactly one, which is more research is necessary.

        And that's a conclusion you can take to the bank (after the grant comes in, of course).

      • by wvmarle (1070040) on Tuesday August 24, 2010 @02:30AM (#33351560)

        Two interesting points are missing (maybe I should go and read TFA).

        1) The actual variation measured in decay of Si-32 and Ra-226. How small is small? Second, third, fourth significant digit? Even smaller maybe?

        2) The experimental precision of the Pu-238 experiment.

        The precision of 2) should be at least an order of magnitude better than the precision of 1) to be able to reasonably rule out solar effects in case of 2). Considering experiment 2) is done on board a space craft and 1) is done on earth, I don't expect this to be the case.

      • Re: (Score:3, Informative)

        by Mt._Honkey (514673)
        Yes, and the difference in isotope is very important here. Si-32 is a beta emitter, which is the type of decay that one might possibly expect to be affected by neutrinos if they had any effect at all, because neutrinos are emitted along with the beta. Ra-226 and Pu-238 are both alpha emitters, which makes the seasonal variation in Ra-226 even stranger because neutrinos are not involved at all in alpha decay.
    • by AJWM (19027) on Tuesday August 24, 2010 @12:42AM (#33350936) Homepage

      Except that Cassini isn't measuring the decay rate, as the other experiments were directly, but measuring the power output from thermocouples heated by the energy of the particles captured (by the overall mass of the thermocouple/isotope system) from the decaying material -- which also has a rather long half-life.

      There's a lot of averaging out of effects in all that, and the effect they're looking for is quite small. The link didn't mention a lower bound for the detection sensitivity based on looking at Cassini power outputs. Cassini doesn't rule it out, it just sets an upper bound for the effect -- and if the effect were that strong we'd likely have noticed it before now.

      • Re: (Score:3, Informative)

        by radtea (464814)

        The link didn't mention a lower bound for the detection sensitivity based on looking at Cassini power outputs.

        The arxiv.org link at the bottom of the article provides just that. The variation in counting (not decay) rates observed is about 0.1% over the 3% variation in Earth's orbital distance, implying about (3E-2)/R**2 as the relationship, and the Cassini results put an upper limit on of less than (0.84E-4)/R**2 and comparable for a /R term.

        Ergo, the Cassini results put on a limit that is more than two orders of magnitude smaller than the original observation. Ergo, the original observation is not due to simply

    • Re: (Score:2, Interesting)

      by samullin (1850996)
      I believe the seasonal variation in measured decay rates is likely to be a mundane explanation, but I also believe that the evidence from RTG power output in the article you linked is too indirect to prove or disprove the hypothesis. The author goes into a lot of detail to model the RTG thermal efficiency but the variations in decay rates in the attached figure were on the same order as his estimated error in the RTG model. Conceptually, it seems like this is an experiment that can be repeated with a good
  • by Guppy (12314) on Tuesday August 24, 2010 @12:39AM (#33350920)

    One of the really cool parts of this finding -- in modern times, experimental particle physics has required increasingly huge machines (and budgets) to participate. For a change, here's researchers everywhere can participate in, possibly revolutionary, and for very little cost.

  • Electro-Weak force (Score:3, Interesting)

    by jameskojiro (705701) on Tuesday August 24, 2010 @12:44AM (#33350954) Journal

    Strong Magnetic Fields and High temperatures can influence the Weak Nuclear force, causing it to change.

    We have already coupled the forces of ElectroMagnetism and the Weak force in particle accelerators, why is this of any surprise?

  • More info (Score:3, Informative)

    by PinkyGigglebrain (730753) on Tuesday August 24, 2010 @12:51AM (#33351010)
    Found another article from 2008 [astroengine.com] that postulates that the Earth/Sun distance may also have an effect on isotope decay rates.

    There was also some "fringe" claims back in the early 1990's about how high voltage electrical fields affect alpha decay in isotopes. A quick search turned up a patent [freepatentsonline.com].

    If these claims are substantiated its going to hit more fields than we expect. IIRCC current theory's relating to atomic decay, both classic and quantum, state that the decay rate of unstable atoms is totally random and does not change under any normal conditions. This finding would seem to dispute that, even raising the possibility of accelerating the decay of radioactive atoms into stable one. Might be a way of dealing with the nuclear waste issues if its true and we can figure out how to induce it in the lab. Who knows, once we understand it we might be able to make the effect go the other way and create useful isotopes without needing a reactor.

    No mater the case this is interesting. I'm looking forward to seeing more research on this.
    • Re: (Score:3, Informative)

      by sFurbo (1361249)

      IIRCC current theory's relating to atomic decay, both classic and quantum, state that the decay rate of unstable atoms is totally random and does not change under any normal conditions.

      Not quite, k-electron capture are affected by the cross section of the k-electrons with the nucleus, which might be slightly changed by pressure or chemical bonds. This can lead to a change of up to 1%. The fully ionised nucleus would be stable if there is no other decays possible.

      Other decay modes should also be affected, as the energy levels of the nucleus is pertubed by the electron-density, but this would be a much smaller effect, as the electron cloud is not directly involved in these decays.

  • The article says:

    A lump of radioactive cesium-137, for example, may decay at a steady rate overall

    But is that true? I thought a more correct statement would be that Cesium-137 decays at a particular rate on average. I'd have thought you'd expect some minor fluctuations in decay rates would be expected.

  • This is important because the rate of decay is very important not just for antique dating, but also for cancer treatment, time keeping, and the generation of random numbers.

    How is radioactive decay used for time keeping?

    • Seriously? You use this site and have never heard of an atomic clock?

  • Methinks we've got another outbreak of N-Rays or CNF in the works.

    Just a hunch...

  • You mean the glitch in my PC is really POM dependent?

  • But if it's neutrino's doing this, *and* there's a notable difference to what happens to these experiments, depending on what side of the globe you're on, then the amount and the effect of neutrino's racing through earth, us, and whatnot cannot be in any way insignificant, meaning that they must, somehow, interact with us. You know. Give us cancer and that sort of thing. Make us more heavy, I don't know. Or do neutrino's *only* affect isotope-degradation-experiments ?

    • Re:Question (Score:4, Interesting)

      by Angst Badger (8636) on Tuesday August 24, 2010 @01:34AM (#33351268)

      The trouble is that the effect is correlated with the 33-day rotation of the solar core. If varying rates of nuclear decay affected cancer rates -- which they could -- the problem with measuring it is the speed with which cancer progresses. Since we can't detect cancer the moment a cell goes rogue, any variability in oncogenesis rates over a 33-day period would be lost in the statistical noise.

      If you do figure out a way to detect oncogenesis that precisely, you'll be too busy curing cancer to worry much about solar neutrino flux.

  • Is it possible that the decay changes and the solar activity just happen on the same schedule due to some other external force that synchronizes them, or due to some sort of inherent cyclicality that began at a similar instant in the distant past and remains synchronized?

    Other than human error I can't think of any other alternate explanations for the correlation.

    • Due to the Earths orbit not being a perfect circle the Earth/Sun distance is not constant, it changes during the year. The article linked in the summary mentions the Neutrino flux from the sun, may be responsible. Or it may be something new. Further tests are needed to isolate the effect, if its real. That is what science is all about.

      As to you not being able to come up with any alternate explanations, I think Shakespeare had it right in Hamlet "There are more things in heaven and earth, Horatio, Than
  • Solar flare, maybe, but seasonal? That sounds like an artifact.
    • Re: (Score:3, Informative)

      Earths distance from the sun isn't constant. On Winter Solstice (Northern Hemi) the Earth is closer to the Sun than the Summer Solstice (Northern Hemi). Being closer Solar effects like the Neutrino flux would be more intense.
  • Ever since I heard radioactive decay mentioned as a true random process, I have wondered how long it would take until we figured out that it wasn't true random, after all. This story sounds like we may be getting closer.

  • by Old Wolf (56093) on Tuesday August 24, 2010 @03:31AM (#33351920)

    Beta decay is: neutron -> proton + electron + antineutrino.

    If you add a neutrino to each side you get: neutron + neutrino -> proton + electron + energy

    So is it not plausible that the probability of a nucleus undergoing beta decay is related to the number of neutrinos handy?

    A couple of other corollaries: this finding would mean that carbon-14 dating is less reliable than previously thought; and also that it may be possible somehow to extract historical data about the strength of the sun somehow. (relevant to the AGW debate).

  • by node_chomsky (1830014) on Tuesday August 24, 2010 @07:10AM (#33352974)
    Finally! When I say "Science has been in a perpetual state of being wrong since it's inception", I can now point out fundamental changes in what is thought of as indisputable information. Understand that I am a working scientist, and my attitude is not meant to dismiss science, but to point out that people are often wrong in what they think is objective truth. The world is a bit too complicated for anyone to claim that they have a thorough understanding of the universe. Not to say truth is unobtainable, there is just a lot of it, and it's hard to really wrap your head around the exocentric universe in full.
  • Cause and effect (Score:4, Insightful)

    by Skapare (16644) on Tuesday August 24, 2010 @07:34AM (#33353118) Homepage

    TFA seems to assume "seemed to be influenced by activities inside the sun" and "something produced by the sun had traveled all the way through the Earth" ... e.g. that it is the sun affecting the isotopes. Why not the other way around? I'm sure there are some of these isotopes inside the sun. So if their decay rates change, won't that have an effect on the sun?

    • Re: (Score:3, Insightful)

      by shadowofwind (1209890)

      Another possibility would be that some other influence is affecting both the decay rates and the solar activity. If I had to make a poorly informed guess, I would pick that over the idea of the sun influencing the decay rates.

      Assuming this decay rate thing is real, and not some subtle misunderstanding about the measuring technique, am I the only one who thinks this is a fantastic result?

  • Decades Old News (Score:3, Informative)

    by b4upoo (166390) on Tuesday August 24, 2010 @07:40AM (#33353162)

    If we went clear back to 1965 you could attend college classes in astronomy that included the teaching that the sun could not produce as much energy as it does with nuclear reactions without having too short a life span. The calculations of that era suggested that gravity was the most likely source of solar heat generation.

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