Nuclear decay rates possibly correlate with distance from Sun

[Mk]

http://arxiv.org/abs/0808.3283
Unexplained periodic fluctuations in the decay rates of Si-32 and Ra-226 have been reported by groups at Brookhaven National Laboratory (Si-32), and at the Physikalisch-Technische-Bundesandstalt in Germany (Ra-226). We show from an analysis of the raw data in these experiments that the observed fluctuations are strongly correlated in time, not only with each other, but also with the distance between the Earth and the Sun. Some implications of these results are also discussed, including the suggestion that discrepancies in published half-life determinations for these and other nuclides may be attributable in part to differences in solar activity during the course of the various experiments, or to seasonal variations in fundamental constants.
This is weird as hell. As far as I knew, nuclear decay rates were not affected by anything, except beta decay under electromagnetic fields. This could possibly have huge consequences in other sciences. Personally, I immediately went to post this in Earth. Paleoclimatologists collect data over hundreds to millions of years based on isotope ratios and nuclear decay rates. Anthropologists, archeologists, geologists— they all do as well, but who knows!

In summary, we have presented evidence for a correlation between changes in nuclear decay rates and the Earth-Sun distance. While the mechanism responsible for this phenomenon is unknown, theories involving variations in fundamental constants could give rise to such effects.
By that they mean the fine structure constant. They cite this paper: http://arxiv.org/abs/0806.4317

They also cite this paper in saying:
http://arxiv.org/abs/0808.3156
These results are also consistent with the correlation between nuclear decay rates and solar activity suggested by Jenkins and Fischbach [18] if the latter effect is interpreted as possibly arising from a change in the solar neutrino flux. These conclusions can be tested in a number of ways. In addition to repeating long-term decay measurements on Earth, measurements on radioactive samples carried aboard spacecraft to other planets would be very useful since the sample-Sun distance would then vary over a much wider range. The neutrino flux hypothesis might also be tested using samples placed in the neutrino flux produced by nuclear reactors.
Interesting, all these papers came out at about the same time in 2008. Nice stuff. I'm not a frequent poster in this forum, but I thought it would be placed well here and get some good discussion on these three papers. If it should be moved by a moderator, then go ahead and move it.

[arivero]

http://arxiv.org/abs/0808.3283
This is weird as hell. As far as I knew, nuclear decay rates were not affected by anything, except beta decay under electromagnetic fields.

I guess that this is the conjecture under test: that beta decay rates could be sensible enough to the variation of solar neutrinos. Weird indeed.

[cesiumfrog]

Has the paper been (expert) peer reviewed? (A little thing like that doesn't stop slashdot running with it of course..) Any attempts at running an identical apparatus in the opposite hemisphere?

[CarlB]

Another, somewhat less convincing, recent article with some of the same authors is:

Perturbation of Nuclear Decay Rates During the Solar Flare of 13 December 2006
Jere H. Jenkins, Ephraim Fischbach
http://arxiv.org/abs/0808.3156

As far as the validity of the paper, they've got 6 authors, which is a bit too many to overlook something obvious, but only Jenkins has a lot of papers to his credit.

I can see how a neutrino flux might modify beta decay; it would be a sort of lasing effect if the frequencies were right. But I don't see how neutrinos could possibly effect a decay that emitted an alpha particle, unless it was a cascade or something like that, but that's not the case, Ra-226 is a straight alpha emitter:
http://en.wikipedia.org/wiki/Radium

Rather than neutrino flux, I would think that a dependence on gravitational potential would be more likely, especially given that the rate has a small phase difference from the distance to the sun (a lag).

[Vanadium 50]

I think it's far more likely that the authors are observing a seasonal variation in detector performance.

There are two things in the back of my mind when I read this. One is that the authors were re-analyzing someone else's data: they weren't there when it was taken. That immediately puts them at a disadvantage. (In fact, it's even possible that this effect was noticed by the original experimenters, and the reason identified).

The other is that Fischbach has a track record of finding dramatic new physics effects in other people's data - effects that subsequently are shown not to exist.

[vanesch]

I think it's far more likely that the authors are observing a seasonal variation in detector performance.


This is also what came to my mind. I once had an unexpected variation in a detector efficiency with a time constant of a few hours, and it turned out to be perfectly correlated with the airconditioning which switched on and off to keep the temperature about constant (but nevertheless, the 0.5 degree variation or so was noticable).

That said, in the paper, they compare to a reference each time, which seems to have remained flat, so in principle this has been taken into account...

[CarlB]

In addition, Fishbach has a paper claiming that the neutrinos weigh at least 0.4 eV (snicker). But there are a bunch of other authors.

[arivero]

I think it's far more likely that the authors are observing a seasonal variation in detector performance.

There are two things in the back of my mind when I read this. One is that the authors were re-analyzing someone else's data: they weren't there when it was taken. That immediately puts them at a disadvantage. (In fact, it's even possible that this effect was noticed by the original experimenters, and the reason identified).

He argues that it is different latitude; but one could be safer if it were different hemisphere. If they are in the same day/night pattern, I vote for radiation and consum patterns from the light bulbs/discharge tubes. The air conditioning system is also a suspect, yes.

The other is that Fischbach has a track record of finding dramatic new physics effects in other people's data - effects that subsequently are shown not to exist.

There is a scent of almost-recursivity in this research: Do you mean that there is a pattern in Fischbach data :biggrin:?

[arivero]

I can see how a neutrino flux might modify beta decay; it would be a sort of lasing effect if the frequencies were right. But I don't see how neutrinos could possibly effect a decay that emitted an alpha particle, unless it was a cascade or something like that, but that's not the case, Ra-226 is a straight alpha emitter:
http://en.wikipedia.org/wiki/Radium


Perhaps an increase in the phase space available for disintegration? No sure, but for fision there is a peculiar colective phenomena around: the lower peak, corresponding to the more abundant subproduct, lives at 81 GeV (told at http://www.physicsforums.com/showthread.php?t=227263 ). In any case, in the NZ plot you can see that the other huge peak in the total collection of measured beta decays corresponds to the corner of the theoretical alpha line, next to the magic N=82.

Rather than neutrino flux, I would think that a dependence on gravitational potential would be more likely, especially given that the rate has a small phase difference from the distance to the sun (a lag).

Even -Lubos labeled me recently as an archetypal model of gullibility- I myself am unable to see how a grav variation could work. Next step is to look for tidal patterns.

[Vanadium 50]

That said, in the paper, they compare to a reference each time, which seems to have remained flat, so in principle this has been taken into account...

The BNL work compares Si-32 to Cl-36. Si-32 is a beta emitter, and Cl-36 decays by K-capture most of the time, with a tiny fraction of positron emission. So you will have different energy spectra, a different particle mix, and a different number of Auger electrons. A subtle difference in response is not hard to imagine.

Note that the original experimenters didn't have to worry about this, since over a multiyear run these effects would average out.

[sanman]

A pair of researchers are claiming to have found variance in alpha decay rate, which they have correlated with solar neutrinos:

http://physicsworld.com/cws/article/news/36108

Are they onto something, or just barking up the wrong tree?

[humanino]

You've not checked, have you ?
Nuclear decay rates possibly correlate with distance from Sun

[hamster143]

The most likely explanation is an imperfection in their experimental setup (either the clock or the detector) that makes readings depend on an external factor.

As far as correlations with solar flares, their chart is not very convincing. They should set up two systems in two different rooms (different buildings, if possible) and see if they get strong correlation between decay rates. If there is, then you can search for an external factor that affects decay rates - solar flares, neutrinos, axion flux, etc.

[Vanadium 50]

They should set up two systems in two different rooms (different buildings, if possible) and see if they get strong correlation between decay rates.

As mentioned in the other thread, this is impossible. The authors did not do the experiment; they are analyzing someone else's experiment.

[jtbell]

You've not checked, have you ?
Nuclear decay rates possibly correlate with distance from Sun

Um, that's this very thread. :confused:

Or did someone merge two threads?

[Vanadium 50]

The threads were merged.

I looked at the solar flare data and find it completely unconvincing. I see the decay rate bouncing all over the place, and sometimes this bouncing happens to be near a solar flare. The authors assume they have no systematic uncertainties, which is clearly not the case if you ask how well the off-flare data fits the curve.