Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!


Forgot your password?

The Strange Case of Solar Flares and Radioactive Decay Rates 408

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.'"
This discussion has been archived. No new comments can be posted.

The Strange Case of Solar Flares and Radioactive Decay Rates

Comments Filter:
  • 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].
  • 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.

  • 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?

  • by c0lo ( 1497653 ) on Tuesday August 24, 2010 @12:46AM (#33350970)

    really nice find - that wrecks their thesis at the bottom.

    Huh? Why?

    Assuming the explanation is "Seasonal variation in neutrino flux", because 2 radioactive elements (silicon-32 and radium-) seems to show a neutrino capture cross-section higher than another one (Pu238)? Would this be so unusual?

  • by c0lo ( 1497653 ) on Tuesday August 24, 2010 @12:49AM (#33350988)

    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 dakameleon ( 1126377 ) on Tuesday August 24, 2010 @12:59AM (#33351062)

    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 samullin ( 1850996 ) on Tuesday August 24, 2010 @01:03AM (#33351088)
    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 Geiger counter on a cheap satellite without relying on indirect measurements.
  • by Black Parrot ( 19622 ) on Tuesday August 24, 2010 @01:14AM (#33351158)

    Just like, as is proven by history, at least a couple of million Chinese and Egyptians.

    Genesis literalists like to "show" that if you started with eight people around the assumed time of the flood, it takes only a modest exponential growth rate to get the world's current population. Too bad they don't pause to consider what their curve predicts for just a few hundred years beyond the starting point.

    And therein lies, I think, the big cognitive difference between scientists and traditionalists. Scientists are all over their own hypotheses with "what about this?" questions, but a traditionalist doesn't look beyond the most superficial analysis if it gives the desired result.

  • by Anonymous Coward on Tuesday August 24, 2010 @01:17AM (#33351170)

    Even us Southern Baptists (mostly) think they're loons. They guys at the top are in it for the money, trying to inflate an unimportant issue to a major doctrinal point (coming down on the wrong side of it, acting contrary to traditional church leaders like Augustine).

  • 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.

  • Re:Earth Date (Score:5, Interesting)

    by wvmarle ( 1070040 ) on Tuesday August 24, 2010 @02:20AM (#33351486)

    They found the same results in historical data of various labs. That of course does not rule out such a mundane reason, it makes it less likely.

    I agree that there are certainly seasonal variations in labs, even if you try to keep it as constant as possible. But for starters the air in the lab has to be refreshed all the time, and this air comes from the outside. I can imagine the composition changes between summer and winter (plants don't grow in winter).

    The 33-day cycle another replier mentioned is interesting of course, as it correlates with a solar cycle and no normal human cycles.

    A multi-year cycle correlating to solar spots could be interesting.

    Effects correlating to known solar flares too.

  • Re:Very interesting. (Score:3, Interesting)

    by The Master Control P ( 655590 ) <ejkeever@neDEBIA ... com minus distro> on Tuesday August 24, 2010 @02:58AM (#33351742)
    You do realize that as a classical field theory General Relativity has nothing to do with atomic decay?

    And that GR has been subjected to one experimental test after another for over 90 years now and passed them all?
  • 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).

  • Re:Earth Date (Score:1, Interesting)

    by AlecC ( 512609 ) <aleccawley@gmail.com> on Tuesday August 24, 2010 @06:30AM (#33352786)

    ...correlating to a 33-day cycle that they hypothesize to be that of the Sun's core. There is no other evidence for such a rotation: the Sun's surface rotates in 28 days. An intetresting observation, and an interesting theory, but still very hypothetical.

  • 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.

  • Not entirely... (Score:3, Interesting)

    by postermmxvicom ( 1130737 ) on Tuesday August 24, 2010 @11:33AM (#33355962)
    Fun sentiment, but not true. For years critics ridiculed the book of Daniel for having someone name Belshazzar as king of Babylon. Ultimately, archeology [wikipedia.org] supported the Bible. We could probably get into a long drawn out tit for tat about different things, but I am uninterested in that. I only wanted to point out that your claim about "every" time is nothing but wishful hyperbole. Perhaps, you only meant it that way, and not as literal truth - in that case I apologize. Let's not get into a flame war over it :)
  • Re:Not entirely... (Score:3, Interesting)

    by Chris Burke ( 6130 ) on Tuesday August 24, 2010 @12:24PM (#33356750) Homepage

    I think it's fair to distinguish between historical claims regarding the periods in which the Bible was written (or the accounts it was based on were from), and claims about physics, geology, and other natural sciences (which, imo, the Bible actually makes very few if any claims about anyway).

    I think it's unsurprising that the Bible would have accurately named a contemporaneous ruler, yet not so accurately give the age of the planet earth.

"If you lived today as if it were your last, you'd buy up a box of rockets and fire them all off, wouldn't you?" -- Garrison Keillor