Via slashdot:
A couple of days ago, WUWT carried a story that was rather shocking: some physicists published claims they have detected a variation in earthly radioactive decay rates, big news by itself, but the shocker is they attributed it to solar neutrinos.
The findings attracted immediate attention because they seemed to violate two known basic facts of physics:
1. Radioactive decay is a constant
2. Neutrinos very rarely interact with matter and are hard to detect when they do.
For example: trillions of the neutrinos are zipping through your body right now. So why would they interact with radioactive elements in a more detectable way?
Discover Magazine’s blog 80beats followed up on the initial story buzzing around the web this week and interviewed several physicists who work on neutrinos. The neutrino-affecting-radioactive decay theory is being questioned.
Excerpts:
“My gut reaction is one of skepticism,” Sullivan told DISCOVER. The idea isn’t impossible, he says, but you can’t accept a solution as radical as the new study’s with just the small data set the researchers have. “Data is data. That’s the final arbiter. But the more one has to bend [well-establish physics], the evidence has to be that much more scrutinized.”
Among the reasons Sullivan cited for his skepticism after reading the papers:
- Many of the tiny variations that the study authors saw in radioactive decay rates came from labs like Brookhaven National Lab—the researchers didn’t take the readings themselves. And, Sullivan says, some are multiple decades old. In their paper, Fischbach’s team takes care to try to rule out variations in the equipment or environmental conditions that could have caused the weird changes they saw in decay rates. But, Sullivan says, “they’re people 30 years later [studying] equipment they weren’t running. I don’t think they rule it out.”
- The Purdue-Stanford team cites an example of a 2006 solar flare, saying that they saw a dip in decay rates in a manganese isotope before the occurrence that lasted until after it was gone. Sullivan, however, says he isn’t convinced this is experimentally significant, and anyway it doesn’t make sense: Solar neutrinos emanate from the interior of the sun—not the surface, where flares emerge. Moreover, he says, other solar events like x-ray flares didn’t have the same effect.
- If it were true, the idea would represent a huge jump in neutrino physics. At the Super-Kamiokande detector, Sullivan says only about 10 neutrinos per day appeared to interact with the 20 kilotons of water. Sullivan says the Purdue-Stanford team is proposing that neutrinos are powerfully interacting with matter in a way that has never before been observed. “They’re looking for something with a very much larger effect than the force of neutrinos, but that doesn’t show up any other way,” he says.
Fischbach and Jenkins, who have published a series of journal articles supporting their theory on neutrinos and radioactive decay, emailed DISCOVER to respond to these criticisms of their work. Regarding the first one, the researchers defended the integrity of the data even though they didn’t take it themselves, saying the experiments “were carried out by two well-known and experienced groups. We have published an analysis of these experiments, in Nuclear Instruments and Methods … showing that the potential impact of known environmental effects is much too small to explain the annual variations.”
Tim Clark says:
August 27, 2010 at 10:32 am
What’s .2% of 4.5 billion years?
Nine million years.
One of the first easy questions I’ve ever seen on this site…
Let’s not get too carried away with invalidating radiometric dating methods. Major extinction events are highly correlated with massive flood basalt eruptions…
Flood Basalts and Extinctions
I’d prefer to think that these things only happen every 20 to 60 million years and not every 2 to 6 thousand years.
😉
I understand the general skepticism, but I don’t understand why this discovery is so bizarre as to be considered more bizarre than the quantum behaviors that have already been verified as fact.
Change in the decay rate of radioactive isotopes has already been verified (since 1977) to occur under certain conditions, via the quantum zeno (and anti-zeno) effect. In other words, the rate of decay is already known to only be constant if environmental conditions are constant. It would seem like this new discovery would expound on that. If the rate of neutrino “observations” of an atomic nucleus vary, the decay rate will vary.
http://en.wikipedia.org/wiki/Quantum_Zeno_effect
Jim,
United Nuclear is one of my favorite sites. They have scintillation detectors [spinthariscopes]. They have radioactive isotopes. They even have parts for death rays! How cool is that?
Here is what I wrote in the Discover comments:
Two points:
The statement “decay rates are constant” is a statement describing local physics. As far as general relativity goes decay rates depend on the topology of space time; the same is true of the velocity of light, another so called constant, that is only locally constant.
Any interaction with the neutrino field introduces an extra weak vertex. No energy exchange can happen without this extra vertex. The extra weak vertex introduces in the probability a 10^-12 diminution, and they are talking of 0.2% effects. It cannot be neutrinos.
Even if there is a correlation with neutrino bursts or solar flares, correlations are not causation. The whole solar system could be going through a rough patch of space time.
Measuring accurately the velocity of light over a few sun cycles is an easier experiment than measuring decay rate changes.
I would vote for data contamination from instrumental biases. Otherwise this would be a first measurement of gravitons, 😉
BTW, It is true that when neutrinos were first visualized Fermi, I think, said: “who ordered that?”. Since then, and particularly with the data gathered in electron positron collisions the past twenty years or so, the standard model with its three neutrinos is as well established as the model of the atom.
Anthea Collins says:
August 27, 2010 at 8:51 am
Forgive my ignorance, but is the change in decay rate of an element really significant? Surely it would be so minute as to be only worthy of study for the sake of study. (I stand by trembling with my hard hat pulled right down!)
Normally U235 has a very minor decay rate, but hit it with the right speed of neutron, and suddenly it becomes “decay on demand” – with associated flash, bang, and mushroom cloud, so altering the decay rate of a substance has its uses.
Similarly but in the other direction, there are decay mechanism which “suck in” an electron to turn a proton into a neutron. In the case of an completely ionised sample, this decay mechanism completely stops (because there are no electrons) – so the old canard of it being a constant was never really true.
For more prosaic uses of radioactive decay, it is used to date various things on this planet like rocks and carbon based matter for purposes of geology/history etc. Any errors will mean that these dates will be wrong.
There is also the mechanism behind how it could vary. It would mean what we know about particle physics, isn’t actually true…
Might want to check out this stuff I was looking at a couple of years ago.
First is a 2008 study by the same authors (Jenkins, Fischbach) with different radioisotopes and seasonal changes in decay rate aligned with change in distance from sun seen at two different facilities.
http://arxiv.org/PS_cache/arxiv/pdf/0808/0808.3283v1.pdf
Here’s more data on the Voyager RTG (radio thermal generators).
1999 paper on the RTG design and details about the degradation studies of the materials.
http://arxiv.org/PS_cache/arxiv/pdf/0808/0808.3283v1.pdf
And below a 2006 paper on actual vs. predicted performance over 28 years over a distance of 1AU (at launch) from the sun to 101AU out in 2006.
http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/38760/1/06-0391.pdf
Note that after 28 years the thermopile was producing 5% more power than predicted which seems an excessively large error given the robust degradation studies of the materials.
Oops, my previous comment regarding verification of the quantum zeno effect on radioactive isotopes was off by a few decades.
Experimentation regarding rate of radioactive decay was certainly hypothesized by 1977 (much earlier, actually), but experiments back then where to verify the effect on the decay of other quantum systems, not radioactive isotopes.
Below is a link to a Nature article in 2000 that specifically discusses confirmation of the quantum zeno effect in regards to the rate of radioactive decay.
Z says: “Any errors will mean that these dates will be wrong.”
Of course the idea that there is only a certain degree of precision in the methods is known, studied and thus assumed. We are always looking for ways to increase precision; nor would this be the first time that the very accuracy of the methods has been called into question – sometimes, it turns out with justification.
Which is why we never rely on a single measurement or method in the first place; grabbing at every “yardstick” available and only having such confidence in the results as their concurrence suggests is, or is NOT, warranted.
One might even be inclined to examine how these ideas apply to the measurement of Global Mean Temperature.
“It would mean what we know about particle physics, isn’t actually true…”
Which would be . . . really frickin’ cool!
Just a couple of comments, for your consideration:
1) If you look at the bulk of the decay data, the data will follow the normal exponential, thus the general decay trend is as expected. However, you can see a fine structure (the fluctuations that appear to have an annual period) as the data points oscillate along the general decay line. There should be no ordered trends in a “random” data stream, right?
2) Alpha and beta decays are two entirely different processes, and even within the definition of beta-decay, there are multiple processes (beta-minus, beta-plus, K-Capture). And then if you look at the energetics of the decays, which are unique to each isotope…and the fact that beta-decays are dependent on the energy available, the idea that neutrinos could kick in a few eV as they pass through a mass, and that the cumulative sum of the energy added to a system could be enough to alter the decay constant slightly, is not out of the question.
3) The Purdue group did an exhaustive analysis of the detector systems used in the two different experiments (one data set 30 years old, the other ten years old), looking at the possible known environmental effects (including gravity/time and some others) and found that none of these could have been the single culprit to cause this, and that the sum of the causes was not likely to have been effective to an order enough to cause the +/- 0.1% oscillations. It could also be pointed out that the two data sets, taken in laboratories on separate continents, with two different types of detectors (one an ion chamber measuring photons, the other a proportional counter measuring beta particles), measuring three different decay chains, actually correlated in time with each other for the two years the experiments overlapped.
Dave Springer says:
August 27, 2010 at 1:00 pm
“Note that after 28 years the thermopile was producing 5% more power than predicted which seems an excessively large error given the robust degradation studies of the materials.”
The only surprising thing here is how accurate their prediction was. Especially since there are lots of other effects they do not seem to have been able to include in the model, such as the long term effect of cosmic rays on the thermocouple materials, which could easily either increase or decrease the thermoelectric emfs, etc. Moreover, where there was any uncertainty in their figures, they could be expected to have made somewhat conservative choices, because it doesn’t matter if the thermopile outperforms its specifications, but it matters a lot if it underperforms. It is also not clear from the pdf whether they included the gradually increasing energy output of the daughter nuclides. There is no evidence of variable decay rates here.
it is observations of the unusual like this that help us to make progress
i for one not only doubt the neutrino link but doubt the neutrino, period
the bohr model works reasonably well but i am sure we can come up with something even better
@Paul Birch
“the long term effect of cosmic rays on the thermocouple materials, which could easily either increase or decrease the thermoelectric emfs”
So those could explain either an increase or a decrease in degradation of thermocouples. Easily huh? Try going into a little more detail on how that could easily go either way.
@Paul Birch
Actually Paul, I just noticed I put the wrong link in to the Voyager RTG materials degradation study so you didn’t actually read it before concluding it wasn’t thorough. LOL
Here’s the correct link:
http://www.ligo.caltech.edu/docs/P/P990034-00.pdf
Try actually reading it before you start commenting on how well it was done.
Some of us here have been debating the effect as an enhancement of beta decay, hypothetically by solar neutrinos. On reading one of the papers just now, I noticed that one of the radionuclides in question was Ra-226, which is an alpha emitter, not the beta-emitting Ra-228 (which I’d previously mistakenly assumed or misread it as). This makes it even harder to see how neutrinos could be responsible, since they are not involved in alpha decay. The other radionuclide, Si-32, is a beta emitter, while Mn-54, mentioned in the article, apparently decays by K-capture; both of these are Weak processes. So the suggestion is that the mechanism is affecting all three decay modes similarly, which also seems rather unlikely. Note, by the way, that K-capture decay rates can be reduced quite easily, by exciting or ionising the atom (if there aren’t any K-electrons, they can’t be captured).
“”” anna v says:
August 27, 2010 at 12:46 pm
Here is what I wrote in the Discover comments:
Two points:
The statement “decay rates are constant” is a statement describing local physics. As far as general relativity goes decay rates depend on the topology of space time; the same is true of the velocity of light, another so called constant, that is only locally constant.
Any interaction with the neutrino field introduces an extra weak vertex. No energy exchange can happen without this extra vertex. The extra weak vertex introduces in the probability a 10^-12 diminution, and they are talking of 0.2% effects. It cannot be neutrinos.
Even if there is a correlation with neutrino bursts or solar flares, correlations are not causation. The whole solar system could be going through a rough patch of space time.
Measuring accurately the velocity of light over a few sun cycles is an easier experiment than measuring decay rate changes.
I would vote for data contamination from instrumental biases. Otherwise this would be a first measurement of gravitons, 😉
BTW, It is true that when neutrinos were first visualized Fermi, I think, said: “who ordered that?”. Since then, and particularly with the data gathered in electron positron collisions the past twenty years or so, the standard model with its three neutrinos is as well established as the model of the atom. “””
I would agree with your last statement Anna. Moreover, I believe there is a rather elegant argument (which I do not have at my fingertips) that says there cannot be any fourth Neutrino, along with its coterie of another bunch of as yet unknown particles.
So any other explanation that would posit some other new unknown particle has to run the gauntlet of a great abhorrence for accepting any new particles; once the Higgs Boson is located.
The more I read about this “discovery” the more I feel that it seems someone discovered a dusty old box full of baseball cards and they have been going through it to see if any of them is valuable.
The initial (current) release of this story; made it sound like JPL or some other modern group had just had their bells rung in some fancy new detector; and had some hitherto unknown phenomena to explain. Better check whether the bells are really ringing first and then try to cook up some causal explanation; please let it not be CO2.
Neutrino flux from the sun presumably follows the inverse square law.
Do any of our various spacecraft whizzing around the solar system (or stuck in the snad on Mars) have instruments that could be bent to the purpose of calculating local radioactive decay rates?
Our nature seems to want things to be ordered and symmetrical. Perhaps our mathematical systems have that bias built into them but, unfortunately, we live in a chaotic universe where we have, so far, found that our mathematical representations of physical processes always seem to be mere approximations of what is really going on. From Newton to Einstein to dark matter and dark energy to inflation and our inability to marry general relativity to quantum physics. Dogmatism is our greatest enemy.
I wish I could tipe beter. “sand”, not “snad”.
Good gravy is my brain off today! I stated “link below” in my previous comment and then forgot to paste the link. OK, one last time…
Below is a link to the abstract published in Nature in 2000, “Acceleration of quantum decay processes by frequent observations”:
http://www.nature.com/nature/journal/v405/n6786/abs/405546a0.html
So, if neutrinos “observe” atomic nuclei, and the rate of neutrion observations changes appreciably, it isn’t a huge leap to assume that the rate of radioactive decay will change as a result of the quantum zeno effect.
Dave Springer says:
August 27, 2010 at 2:21 pm
“Actually Paul, I just noticed I put the wrong link in to the Voyager RTG materials degradation study so you didn’t actually read it before concluding it wasn’t thorough. ”
I did in fact read the pdf you linked, which both described the procedure and gave the predicted and actual power curves. I did not conclude that it wasn’t thorough; on the contrary, I said that it was surprisingly accurate, given that there were many effects they could not have included (because the data did not exist). No one could possibly have known the precise effect of cosmic ray exposure on the thermocouple, for example. I have now also checked the study via your corrected link; my previous comments all stand.
kwinterkorn says:
August 27, 2010 at 2:36 pm
Neutrino flux from the sun presumably follows the inverse square law.
Do any of our various spacecraft whizzing around the solar system (or stuck in the snad on Mars) have instruments that could be bent to the purpose of calculating local radioactive decay rates?
The Voyagers (actually singular) are the best candidates. Their downside is the singular bit.
Perhaps we could go the other way, and see if close sun-orbiting spacecraft are showing anything peculiar (apart from a BBQ taste…)
Dave Springer says:
August 27, 2010 at 2:11 pm
@Paul Birch “the long term effect of cosmic rays on the thermocouple materials, which could easily either increase or decrease the thermoelectric emfs”
“So those could explain either an increase or a decrease in degradation of thermocouples. Easily huh? Try going into a little more detail on how that could easily go either way.”
Thermoelectric emf is a complex materials property. Different alloys, phases and dopings produce different emfs, some higher, some lower. Cosmic rays will change the properties of materials in ways that are very hard to predict; some of those changes will produce materials with higher thermoelectric emfs, some lower. For any given thermocouple combination, it would be a toss-up which way this particular effect would go. Remember, this is a change in addition to the predicted thermal diffusion effects.
Ok this steps on the toes of everyone else’s research, so lets discredit them, and bury it just like famous scientists in the past
http://www.osti.gov/bridge/servlets/purl/481894-QjgVc5/webviewable/481894.pdf
CASSINI RTG ACCEPTANCE TEST RESULTS
RTG PERFORMANCE ON GALILEO AND ULYSSES
Lockheed Martin 5/23/97
Appears to be a smoking gun in figure 8. Galileo RTG power output glitched downwards at the Venus flyby and again on both Earth flybys then bounced back .
Like to see someone dismiss this with something more than vague handwaving about how easily cosmic rays that can both increase and decrease the degradation rate of the thermopile. There was no degradation here, just temporary declines in performance as gravitational assist maneuvers in the inner solar system were accomplished.