Radioactive Decay Apparently Influenced By the Sun 267
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."
Re:Claim not new (Score:5, Interesting)
Well, this is a different data series so I still think it's fair to say that the second study confirms the original finding, although further completely independent confirmation is highly desirable.
Also noteworthy: This apparently only affects beta decay i.e. it seem to hint at an unknown reaction involving the weak force only.
The video goes into some more detail, revealing that they found periodicities that are typical for the core of the sun, only neutrino interaction could account for that.
Neutrinos? (Score:5, Interesting)
If neutrinos are the suspects, wouldn't it be easy to measure the decay rates of one of those nuclei in a strong neutrino flux, close to a large nuclear reactor or in a neutrino beam from an accelerator?
Looks real, but minor (Score:5, Interesting)
Interesting. The effect is well under 1%, but above the noise threshold. Observed for radium (a beta emitter) but not europium (an alpha emitter), with the same experimental setup.
Although heat, pressure, and chemical binding have no measurable effect on radioactive decay, external particles hitting an atom certainly can affect radioactive decay. That's how chain reactions and particle accelerators work.
There's a suspicion here that solar neutrinos might be responsible. Beta decay involves the weak nuclear force, while alpha decay involves the strong nuclear force. Neutrinos are known to interact with the weak nuclear force.
The Fermilab accelerator, which can be used as a neutrino generator, was shut down and decommissioned in September 2011. That would have provided a way to test this hypothesis.
Re:Neutrinos? (Score:5, Interesting)
Since you mention neutrinos, it is also worth noting that there was similar discussion (5 or so years ago) as to whether we can observe periodic variation in the number of neutrinos seen on Earth using various experiments. (Note that periodicities in neutrino rates are not what physicists call "neutrino oscillations". That's an entirely different effect.) Those papers claiming a periodicity included one of the authors on this study of radioactivity decay, and the analysis techniques were disputed by other papers as giving an unacceptably high rate of false positives. The experiments presented counter-analyses showing no significant signal once the probability of false positives was dealt with. (Disclaimer: I was tangentially involved in one of those papers.)
I haven't looked closely enough at the radioactive decay papers to see if the same issue has cropped up again here, but the neutrino periodicity argument is a good example of how these signals can fall apart under closer scrutiny.
bad experiment (Score:5, Interesting)
Disclaimer: i am an experimental physicist from another field (with experience in precision measurements).
looking at the arxiv preprint:
Why would one allow a +-3% variation in *absolute* temperature (figure 6). 6% of 300K are 18K (this is huge. My experiment needed to be recalibrated when the temperature changed by 1 degree). This explains also the *huge* fluctuation of the biasing voltage "lead accumulator" completely propotional to the temperature. which brings me to the next point: the paper makes is sound like this voltage was used *without further stabilization* for biasing the electronics. Why any sane experimentalist would accept such fluctuations when cheap and reliable means (controlled heater, 50cent voltage controller) is beyond my comprehension.
That being said, we talk about some difference on the order of 500 counts (per day, see the paper and multiply the numbers...), respectively 25 per hour or 1 per 2 minutes. I am no expert on it, but at such low count rates an exclusion of the influence of cosmic rays would be needed. Sasly the paper also does not show any dark count rate experiment. If they let the same detector run without anything inside and show the data, then we could make some conclusions.
Ideally they shoud have run an identical detector without a sample in close vincinity at the same time and correlate the fluctuations.
Re:Not enough (Score:4, Interesting)
They're also both papers from the same guy, contrary to what the article implies.