Radioactive Decay Apparently Influenced By the Sun

quax writes "In school you probably learned that the decay rate of radioactive matter is solely determined by the halftime specific to the element. There is no environmental factor that can somehow tweak this process. At least there shouldn't be. Now a second study confirmed previous findings that the decay rate of some elements seems to be under the subtle and mysterious influence of the sun. As of now there is no theoretical explanation for this strange effect buried in the decay rate data."

Comments

Repost of

[buchner.johannes]

http://news.slashdot.org/story/12/08/15/1839202/advance-warning-system-for-solar-flares-hinges-on-surprising-hypothesis

Re:Repost of

[b4dc0d3r]

It's not a repost. That story was about predicting solar flares based on the hypothesis presented here.

They were posted out of order, certainly, and this one is about 2 weeks too late, and offers no value over the previous story.

But this is a better article about the underlying experiments, even though the website waited until today to push it out. Slow news day at WaveWatching.net? Or is this just pimping an old story for blog views?

It's worse than a dupe, and you calling it a repost does not properly insult the report.

Re:Repost of

[bcrowell]

It's not exactly the same, but it is the same kookery warmed over. Here's a summary.
Do rates of nuclear decay depend on environmental factors?
There is one environmental effect that has been scientifically well established for a long time. In the process of electron capture, a proton in the nucleus combines with an inner-shell electron to produce a neutron and a neutrino. This effect does depend on the electronic environment, and in particular, the process cannot happen if the atom is completely ionized.
Other claims of environmental effects on decay rates are crank science, often quoted by creationists in their attempts to discredit evolutionary and geological time scales.
He et al. (He 2007) claim to have detected a change in rates of beta decay of as much as 11% when samples are rotated in a centrifuge, and say that the effect varies asymmetrically with clockwise and counterclockwise rotation. He believes that there is a mysterious energy field that has both biological and nuclear effects, and that it relates to circadian rhythms. The nuclear effects were not observed when the experimental conditions were reproduced by Ding et al. [Ding 2009]
Jenkins and Fischbach (2008) claim to have observed effects on alpha decay rates at the 10^-3 level, correlated with an influence from the sun. They proposed that their results could be tested more dramatically by looking for changes in the rate of alpha decay in radioisotope thermoelectric generators aboard space probes. Such an effect turned out not to exist (Cooper 2009). Undeterred by their theory's failure to pass their own proposed test, they have gone on to publish even kookier ideas, such as a neutrino-mediated effect from solar flares, even though solar flares are a surface phenomenon, whereas neutrinos come from the sun's core. An independent study found no such link between flares and decay rates (Parkhomov 2010a). Laboratory experiments[Lindstrom 2010] have also placed limits on the sensitivity of radioactive decay to neutrino flux that rule out a neutrino-mediated effect at a level orders of magnitude less than what would be required in order to explain the variations claimed in [Jenkins 2008]. Despite this, Jenkins and Fischbach continue to speculate about a neutrino effect in [Sturrock 2012]; refusal to deal with contrary evidence is a hallmark of kook science. They admit that variations shown in their 2012 work "may be due in part to environmental influences," but don't seem to want to acknowledge that if the strength of these influences in unknown, they may explain the entire claimed effect, not just part of it.
Jenkins and Fischbach made further claims in 2010 based on experiments done decades ago by other people, so that Jenkins and Fischbach have no first-hand way of investigating possible sources of systematic error. Other attempts to reproduce the result are also plagued by systematic errors of the same size as the claimed effect. For example, an experiment by Parkhomov (2010b) shows a Fourier power spectrum in which a dozen other peaks are nearly as prominent as the claimed yearly variation.
Cardone et al. claim to have observed variations in the rate of alpha decay of thorium induced by 20 kHz ultrasound, and claim that this alpha decay occurs without the emission of gamma rays. Ericsson et al. have pointed out multiple severe problems with Cardone's experiments.
In agreement with theory, high-precision experimental tests show no detectable temperature-dependence in the rates of electron capture[Goodwin 2009] and alpha decay.[Gurevich 2008]
He YuJian et al., Science China 50 (2007) 170.
YouQian Ding et al., Science China 52 (2009) 690.
Jenkins and Fischbach (2008), http://arxiv.org/abs/0808.3283v1, Astropart.Phys.32:42-46,2009
Jenkins and Fischbach (2009), http://arxiv.org/abs/0808.3156, Astropart.Phys.31:407-411,2009
Jenkins and Fischbach (2010), http://arxiv.org/abs/1007.3318

Claim not new

[JoshuaZ]

The original claim dates from 2008 and 2009. (Original paper here- http://arxiv.org/abs/0808.3283). While TFA claims that this has been confirmed, the group confirming this shares many of the same authors http://arxiv.org/abs/1205.0205. This still has not yet been confirmed by a genuinely independent group. Also the claims still only focus on two specific isotopes Si-32 and Ra-226. One thing worth emphasizing is that this has no bearing on things like the age of the Earth or other uses of radiometric dating. The isotopes are not used generally for radiometric dating and the percentage change in decay rates being observed is tiny. Moreover, for many of the sorts of things we do radiometric dating we have multiple distinct methods that cross-check each other. For example, when doing zircon dating, one can date from both the decay of U-238 and that of U-235 which use distinct decay changes. This may turn out to be some very interesting thing going on, but as of right now the impact is limited even if it is correct.

Re:Claim not new

[Mt._Honkey]

Yeah. There were also come claims with Cl-36, but multiple measurements have the effect in opposite directions and different magnitudes (http://arxiv.org/abs/1208.4357, so they seem more likely to be due to instrumentation effects than real differences

This is one of those "extraordinary evidence" things, and we aren't there yet. Annual variation is always suspect because experimental conditions can change subtly with the weather.

Re:Not enough

[quax]

Yeah, because slashdot always only carries peer reviewed research from top notch Ivy League universities.

Oh wait a second ... these papers are actually peer-reviewed results from Ivy League research universities.

Re:Neutrinos?

[quax]

This would be a good follow up. But producing a high flux of neutrinos is not trivial especially the right kind. The current thinking is that there are three types of neutrinos and that the latter change via a process called neutrino oscillation on the way from sun to earth.

http://en.wikipedia.org/wiki/Neutrino_oscillation

Re:This is exciting

[volsung]

This argument about solar influence on nuclear decay rates has been going on for a few years now. The experimental issues are hard to interpret, because you have to be able to rule out external influences on your counting apparatus. It is extremely hard when the period of your signal matches the orbit of the Earth, which aliases all sorts periodic behavior that has nothing to do with new physics. There are seasonal variations in temperature, cosmic rays, the voltage delivered by the power company, foot traffic near your lab, etc, etc. Verifying that none of these things can possibly influence your results is what takes all the time.

A semi-random selection of earlier papers on the subject:

"Experimental investigation of changes in beta-decay count rate of radioactive elements" (1999):
Claiming 24 hour and 27 day periodicities in the decay rates of cobalt-60 and cesium-137
http://arxiv.org/pdf/hep-ex/9907008v1.pdf

"Power Spectrum Analyses of Nuclear Decay Rates" (2010):
Reports of an annual periodicity in the decay rates of chlorine-36, silicon-32, manganese-56, and radium-226.
http://arxiv.org/abs/1007.0924

"Solar Influence on Nuclear Decay Rates: Constraints from the MESSENGER Mission" (2011)
A study of cesium-137 decay rates on a spacecraft going to Mercury show no change as the spacecraft travelled closer to the Sun.
http://arxiv.org/abs/1107.4074

"Search for the time dependence of the 137Cs decay constant" (2012)
Cesium-137 decays in a detector underground (shielding it from most cosmic rays) show no significant periodicity, with limits much lower than claimed signals.
http://arxiv.org/abs/1202.3662

"Power Spectrum Analysis of LMSU (Lomonosov Moscow State University) Nuclear Decay-Rate Data: Further Indication of r-Mode Oscillations in an Inner Solar Tachocline" (2012)
Studies of strontium-90 decays show a variety of periodic variations, ranging from 0.26 per year to 3.96 per year.
http://arxiv.org/abs/1203.3107

This list goes on and on. There is hardly any consensus on the issue.

Re:Oh. Oh no.

[Hentes]

Every flux (including neutrino and gravity) is proportional to 1/R^2 because we live in 3D. If gravity affected radioactive decay we would've noticed that on our space RTGs. Neutrinos are the most likely answer.

Re:This is exciting

[volsung]

I think the problem is that the link is not yet established. What we have is a link between count rates in a detector observing a sample of some isotope and time of year, which no one disputes (we reasonably assume they are not making up their data). The argument is whether you can make the inductive leap to the claim that radioactive decay rates depend on the amount of solar radiation. As shown in some of those papers above, other experiments don't (like the test with the MESSENGER probe) show the effect you would expect if solar radiation were the cause.

Even if we do find there is an external influence on decay rates (which would be pretty nifty), that definitely does not imply that the times of individual radioactive decays are predictable.

Re:Not enough

[quax]

These are two different data series involving cooperation with different research partners. The article claims confirmation not independent confirmation.