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Follow Up On Solar Neutrinos and Radioactive Decay

An anonymous reader writes "A few days ago, Slashdot carried a story that was making the rounds: a team of physicists claimed to have detected a strange variation in radioactive decay rates, which they attributed to the mysterious influence of solar neutrinos. The findings attracted immediate attention because they seemed to upend two tenets of physics: that radioactive decay is constant, and that neutrinos very, very rarely interact with matter (trillions of the particles are zinging through your body right now). So Discover Magazine's news blog 80beats followed up on the initial burst of news and interviewed several physicists who work on neutrinos. They are decidedly skeptical."

35 of 183 comments (clear)

  1. Wait till the religion fanatics hear this. by BurningTyger · · Score: 5, Insightful

    Wait till the religious fanatics hear this. I have already heard claim from them years ago that radioactive decay is not constant, and that's why carbon dating can not be trusted. The fossils are not a few million years old. The Earth is only a few thousand years old.

    I bet these religious fanatics will now site this article as their proof!

    1. Re:Wait till the religion fanatics hear this. by Antisyzygy · · Score: 5, Insightful

      The problem is that religious fanatics already got a hold of it and accept the results as fact without considering any further review.

      --
      That brings me to an interesting point, / . is just "the ramblings of socially-inept, technology-literate news-mongers".
    2. Re:Wait till the religion fanatics hear this. by muyla · · Score: 4, Informative

      Since TFA says that the decay has slowed down, that would be the case

    3. Re:Wait till the religion fanatics hear this. by causality · · Score: 2, Insightful

      Luckily the detected difference is somewhere around .0001% so I don't think we'll be rewriting history even if their observation is confirmed. Such a small change really makes me wonder if they've actually done the statistical analysis on the results to make sure that they are significant. I'd bet that they will find some relatively run of the mill explanation the explain the changes; something like the detector's efficiency changing based on humidity or temperature. Although something like that would go a long way to explaining seasonal variations, it might be harder to explain the changes that were detected during solar storms/calms.

      Of course, it would be more interesting if this is a real effect. After all, "That's strange" is much more exciting than "We were right".

      The question is that if the difference is that small now, what guarantees do we have that it was always so small and insignificant in the past? Especially when you consider that the Sun is not the only source of neutrinos and radiation in the galaxy.

      --
      It is a miracle that curiosity survives formal education. - Einstein
    4. Re:Wait till the religion fanatics hear this. by aristotle-dude · · Score: 2, Insightful

      The problem is that religious fanatics already got a hold of it and accept the results as fact without considering any further review.

      Sort of like how the internet science fanboys believed in string theory, dark matter, dark energy etc... without any proof?

      --
      Jesus was a compassionate social conservative who called individuals to sin no more.
    5. Re:Wait till the religion fanatics hear this. by Anomalyx · · Score: 2, Interesting
      Actually the constancy of radioactive decay isn't the problem (at least for the relative few "religious fanatics" that have bothered to learn much science. I must admit, most don't have a clue what they're talking about), it's the assumption that absolutely nothing else has influenced the Carbon-14 levels, and that Carbon-14 levels have always been the same (which they actually haven't, but it could theoretically be extrapolated backwards to find the levels at any given date) that creates the problem. Either way, even scientists that eat, sleep, and drink the Millions-of-years-old-evolutionary worldview will agree that carbon dating is BS.

      No matter how 'useful' it is, though, the radiocarbon method is still not capable of yeilding accurate and reliable results. There are gross discrepancies, the chronology is uneven and relative, and the accepted dates are acutally selected dates. This whole blessed thing is nothing but 13th century alchemy, and it all depends upon which funny paper you read.
      --Robert E. Lee (not the general, but the evolutionist)

      And there have been nothing suggesting otherwise since then.

      I don't even care to argue who's right overall, anyone can believe whatever they want, just know that Carbon dating is BS.

      --
      No, there is no "-1 I'LL NEVER ADMIT BEING WRONG!!!" mod.
    6. Re:Wait till the religion fanatics hear this. by Antisyzygy · · Score: 3, Insightful

      One, its quite a bit different than that. Creationists will blow this "evidence" out of proportion before it has time to be reviewed by experts in the field. Then, when its proven false they either will omit that part or will claim something ridiculous and illogical like "If scientists can't even make their mind up about one little thing then they all must be wrong!". Two, I don't believe dark matter or dark energy exists. Im not sure about string theory simply because I don't know enough about it. I know at one time people thought it was silly because it didn't have observable evidence but I am not sure of the current state of the theory.

      --
      That brings me to an interesting point, / . is just "the ramblings of socially-inept, technology-literate news-mongers".
    7. Re:Wait till the religion fanatics hear this. by Anonymous Coward · · Score: 5, Funny

      Luckily the detected difference is somewhere around .0001% so I don't think we'll be rewriting history even if their observation is confirmed.

      So the the Earth is "around" 4,500,000,000 years old and the difference is "around" .0001%? 0.00013% of 4,500,000,000 years is 6000 years! That can't be a coincidence! Earth is 6000 years old!

    8. Re:Wait till the religion fanatics hear this. by zero.kalvin · · Score: 4, Interesting

      Depends on the energy. (A more detailed energy slicing won't be necessary) Low energy neutrinos order of few KeV, come mostly from the sun. High energy neutrinos Above the few KeV threshold mostly comes from Cosmic rays hitting the atmosphere. As for cosmic neutrinos, well good luck with that! I work in a neutrino experiment (ANTARES) , and I wish that we can detect cosmic neutrinos with abundance, it's just that there isn't enough to influence anything.

    9. Re:Wait till the religion fanatics hear this. by Monkeedude1212 · · Score: 5, Insightful

      Except that string theory, dark matter, dark energy, etc, are all theories in that they invite invitation to poke holes in them. Science is an open process that allows anyone to experiment with it and often encourages you to defy the belief in the theory. Most often the giant scientific leaps are when you discover certain properties that don't fit in the theory, or you simply suspend the belief in the theory to find another one that could also be true.

      Religion on the other hand, requires your belief, faith in that belief, and shuns any notion that it could be wrong.

      So yes - if you know of internet science fanboys who said that String Theory MUST be true, than its sort of the same. But there are more of internet science fanboys who say that String Theory COULD be true, and that it requires more verification to either justify or nullify it.

    10. Re:Wait till the religion fanatics hear this. by causality · · Score: 2, Interesting

      Depends on the energy. (A more detailed energy slicing won't be necessary) Low energy neutrinos order of few KeV, come mostly from the sun. High energy neutrinos Above the few KeV threshold mostly comes from Cosmic rays hitting the atmosphere. As for cosmic neutrinos, well good luck with that! I work in a neutrino experiment (ANTARES) , and I wish that we can detect cosmic neutrinos with abundance, it's just that there isn't enough to influence anything.

      What I meant were those caused by transient and relatively nearby events like supernovae or gamma-ray bursts -- things that haven't happened since we had detectors for neutrinos or even knew what neutrinos were. We haven't had a supernova that was visible to the naked eye in Earth's night-time sky in quite a long time, yet when an extremely energetic event like that does happen it may affect the cosmic neutrinos we receive.

      Or maybe someone knows a reason why it couldn't possibly do that. My intented point was, once your realize that this set-in-stone constant isn't, it calls into question how steady, uninterrupted and unaltered the current conditions have been throughout geological periods of time. That does tend to raise questions about methods of dating based on nuclear decay, but as other posters have pointed out, the observed difference (as it stands now) would actually tend to make things a little older than we previously thought.

      --
      It is a miracle that curiosity survives formal education. - Einstein
    11. Re:Wait till the religion fanatics hear this. by Orange+Crush · · Score: 5, Insightful

      And that's a key difference between science and faith. To steal a little from Steven, scientists shouldn't "believe the same thing on Wednesday that they believed on Monday, regardless of what happened on Tuesday." That's not how science works.
      If a researcher discovers something surprising, the next steps are confirming their results and measurements were accurate and are repeatable. Then experiments can be devised to test why this might be so.
      Nobody should do much believing in science. String Theory, Dark Matter and Dark Energy aren't things to be believed. They're just potential and incomplete explanations for what might be going on. The next step is trying to devise experiments to detect these things and/or test the implications.

    12. Re:Wait till the religion fanatics hear this. by chris+mazuc · · Score: 2, Interesting

      We haven't had a supernova that was visible to the naked eye in Earth's night-time sky in quite a long time

      1987 wasn't very long ago.

      SN 1987A was a supernova in the outskirts of the Tarantula Nebula in the Large Magellanic Cloud, a nearby dwarf galaxy. It occurred approximately 51.4 kiloparsecs from Earth,[1] close enough that it was visible to the naked eye. It could be seen from the Southern Hemisphere. It was the closest observed supernova since SN 1604, which occurred in the Milky Way itself. The light from the supernova reached Earth on February 23, 1987. As the first supernova discovered in 1987, it was labeled "1987A". Its brightness peaked in May with an apparent magnitude of about 3 and slowly declined in the following months. It was the first opportunity for modern astronomers to see a supernova up close.

      [...]

      Approximately three hours before the visible light from SN 1987A reached the Earth, a burst of neutrinos was observed at three separate neutrino observatories. This is due to the neutrino emission (which occurs simultaneously with core collapse) preceding the emission of visible light (which occurs only after the shock wave reaches the stellar surface). At 7:35am Universal time, Kamiokande II detected 11 antineutrinos, IMB 8 antineutrinos and Baksan 5 antineutrinos, in a burst lasting less than 13 seconds.

      --
      E pluribus unum
    13. Re:Wait till the religion fanatics hear this. by ShakaUVM · · Score: 4, Insightful

      >>That's not how science works.

      There's three scenarios:
      1) Scientific consensus agreeing with your belief
      2) Scientific consensus holding no opinion on your belief
      3) Scientific consensus disagreeing with your belief.

      Scientifically-minded people are just as prone to choosing to believe things without evidence, which is perfectly acceptable. (People misunderstanding philosophy of science aside.) If you look at Hawking vs. the black hole information paradox, or Hoyle vs. the Big Bang, or any number of other examples, you'll see people stake claims all the time before the facts are in. It's okay.

      The key difference is between a scientifically-minded person and a non-scientifically minded person is when the scientific facts disagree with one's belief. A scientifically-minded person will set that belief aside (perhaps with a caveat that the scientific consensus might later be overturned). A non-scientifically minded person will not.

      Note that I am using the term scientifically-minded, not scientists, as if a physicist who is currently working in macroeconomics will somehow lose his scientific mindset.

    14. Re:Wait till the religion fanatics hear this. by VShael · · Score: 2, Interesting

      Except that, for all it's vaunted ideals, science history in the real world is replete with examples where the establishment CONTINUED to ignore contrary evidence until a new generation of scientists emerged with a less dogmatic viewpoint.

      The most recent example I can think of is the ongoing issue between MOND (or MOG) and Dark Matter, where the existence of Dark Matter is the establishment viewpoint.

      The establishment has, for example, claimed the Chandra observations of the Bullet Cluster collisions definitely refute MOND as a hypothesis (which simply isn't true, but noone thought to ask the MOND people, or check the mathematics).

      It also ignored the results predicted by Stacy McGaugh in the 1999 paper regarding the Power Spectrum distribution in the microwave background radiation. If Dark Matter existed, the second peak would be slightly smaller than the first, and if Dark Matter did not exist, the second peak would be tiny. When the experimental data arrived about a year later, the data indicated Dark Matter did not exist. And as I said above, this was pretty much ignored.

      I've noted Slashdot has a hell of an establishment bias regarding Dark Matter, so don't be surprised if you've never heard of McGaughs paper.

  2. Head asplodes by mcgrew · · Score: 5, Funny

    'What we're suggesting is that something that doesn't really interact with anything is changing something that can't be changed.'"

  3. According to TFA by JoshuaZ · · Score: 3, Interesting

    According to TFA, neutrinos shouldn't be altered much by solar flares which seems to be an almost slamdunk argument against the solar flare part of the claim. In order for this to make sense we'd need wrong not just about neutrino physics but also about basic star modeling. The point that much of the data examined comes from older labs where they have not gone and looked for possible causes in variations also seems to be a strong one. Right now, I'm pretty skeptical of these claims but it should be interesting to see what happens in the next few years.

    1. Re:According to TFA by Qzukk · · Score: 2, Insightful

      The point that much of the data examined comes from older labs where they have not gone and looked for possible causes in variations also seems to be a strong one

      Yeah, from here the first step would be to set up experiments to see if the variation in decay rates really exists, followed by experiments to determine the patten in variation. From there, we can decide whether we think the sun is involved or not, and if so whether neutrinos have anything to do with it.

      --
      If I have been able to see further than others, it is because I bought a pair of binoculars.
    2. Re:According to TFA by Abcd1234 · · Score: 2, Informative

      According to TFA, neutrinos shouldn't be altered much by solar flares

      And according to that *very same article*, the researchers responded, pointing out that some flares are caused by core events, and so may correlate with neutrino flux changes.

      So, what, did you just stop reading half-way through?

  4. How human by spaceman375 · · Score: 2, Insightful

    Of course the trained experts are reluctant to change their view of how the world works. In proper amounts this skepticism is a good thing. I just hope they are open minded enough to recognize the signal in the data, if there is one. As for it being neutrino flux - that's just conjecture. It may simply be distance to the sun's core rather than a particle. What if the fission or fusion of nuclei has an impact on the stability of nearby, possibly entangled nuclei?

    --
    On the one hand you take life too seriously, and on the other, you do not take playful existence seriously enough. Seth
    1. Re:How human by MightyMartian · · Score: 4, Insightful

      If the views stated are correct, then it appears to be a healthy skepticism. In other words "Show us the money". If the data is significant and cannot be explained by being from studies done on old equipment (in other words, if current techniques and equipment are used) and the noticed effect is still there, then the data will rule out.

      It's the way science is always done. But until there's some meaningful verification, these results are inherently unreliable.

      --
      The world's burning. Moped Jesus spotted on I50. Details at 11.
    2. Re:How human by mackai · · Score: 2, Insightful

      Exactly as it should be. Physicists are first, observers. They see something (and like it best when there is some sort of measure that they can put to it). Then next, they are curious; what could this mean?, how could this happen?, what could cause this? Sometimes simultaneous with that, sometimes after, comes; is this real?, are there other causes for this observation or set of observations? Meanwhile, the reporting takes an avenue of speculation; sometimes one possible explanation of several gets the most attention because it is the easiest to express verbally, and most of us reading the reports take it as if true, or at least likely, if there is any credibility to it in our minds. But the community overall keeps looking to see if another (better?) explanation comes to mind or if there is some test that can be examined to strengthen or weaken any such conclusion. Over time, the explanation with the most credibility to the scientific community becomes the one generally accepted.

  5. Sagan responds - by Darth+Snowshoe · · Score: 5, Insightful

    "Extraordinary claims require extraordinary evidence."

    1. Re:Sagan responds - by Abcd1234 · · Score: 2, Insightful

      Absolutely! Which is why more experiments need to be done.

      I don't think the original article came across as definitive. They've noticed a potential something that's very *very* interesting. Skepticism is absolutely warranted, and more work needs to be done, but its interesting nonetheless.

  6. Data is data by Mike+Van+Pelt · · Score: 2, Interesting

    I don't care who might abuse the data in what way -- As Doctor Gregory Sullivan (a skeptic of these results) said in the Discover article, "Data is data. That’s the final arbiter." If nuclear decay rates are varying, I very strongly doubt neutrinos are doing it.

    I think it was Isaac Asimov who said that major scientific revolutions generally don't come with a scientist shouting "Eureka!" They generally start with a scientist looking at the data and saying "That's funny..." If other researches look at the nuclear decay rates, and also see this sort of variability... That would be really, really funny -- something Really Really Big that we are, at the moment, completely clueless about.

    I'm quite confident that the effect, if any, won't much change the dating of fossils, which is what the 4004 BC type creationists want.

  7. Paper, gold - by Darth+Snowshoe · · Score: 3, Interesting

    There are several papers posted on the arXiv.org by Jenkins and Fischbach, this one is my favorite. It's about measurements done on samples of a radioactive isotope of gold - the samples are shaped differently and this alters, presumably, some aspect of their interaction with neutrinos.

  8. I don't see the problem. by jd · · Score: 2, Interesting

    We already know that some radioactive decay results in the release of a neutrino or anti-neutrino. The release of a neutrino is the same as the absorption of an anti-neutrino and vice versa. Ergo, it should be expected that variations in total numbers of neutrinos of the specific energy linked to that specific type of decay event would result in a change in the number of decay events recorded. I simply do not see where this impossibility claim comes from, unless they are claiming that neutrinos of the wrong type/energy are involved.

    We also already know that what appears random is often the result of never being able to have enough data and never being able to make the step sizes infinitely small in the calculations; that randomness, per-se, is actually pretty rare in nature. (Indeed, randomness would seem to violate the requirement that information cannot be created or destroyed. An event is information and physics prohibits information simply "happening".)

    It then follows that radioactive decay almost certainly cannot be a totally random event and therefore almost certainly cannot be absolutely invariate.

    (Indeed, plenty of other people claim to have altered radioactive decay rates, so the claim itself isn't that revolutionary. I'm shocked that the scientific community is so ignorant as to what it itself has been saying for decades. If publishing papers is that important, then reading them must be just as important.)

    --
    It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
    1. Re:I don't see the problem. by Hatta · · Score: 4, Informative

      The release of a neutrino is the same as the absorption of an anti-neutrino and vice versa. Ergo, it should be expected that variations in total numbers of neutrinos of the specific energy linked to that specific type of decay event would result in a change in the number of decay events recorded

      The chances of a neutron encountering an electron and a neutrino of exactly the proper energy at exactly the same time are vanishingly small.

      We also already know that what appears random is often the result of never being able to have enough data and never being able to make the step sizes infinitely small in the calculations; that randomness, per-se, is actually pretty rare in nature.

      Bell's theorem tells us that quantum randomness cannot be explained by a lack of information (hidden variables).

      Indeed, randomness would seem to violate the requirement that information cannot be created or destroyed.

      Where do you get that idea? There is no law of conservation of information. We know that the entropy of the universe always increases. Therefore the information in the universe also increases.

      If you don't see the problem and highly trained theoretical physicists do, you'd be better off asking them where the problem is rather than declaring them wrong.

      --
      Give me Classic Slashdot or give me death!
    2. Re:I don't see the problem. by radtea · · Score: 2, Interesting

      I simply do not see where this impossibility claim comes from

      From the article: "'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."

      That is, your inability to see is a result of your innumeracy. You have said "X effects Y" without any reference to the quantitative, numerical size of the effect.

      The people who actually work on these things for a living have an excellent sense of the magnitudes without having to do a detailed calculation, and know that if the variation in neutrino flux caused by a 3% change in orbital distance was such a big deal then there would almost certainly be all kinds of other evidence for very large effects due to small variations in neutrino fluxes.

      Those effects are not seen, ergo the odds of this effect being due to neutrinos is very small.

      Your post looks like nothing so much as an argument by a medieval, pre-scientific philosopher. It is time to stop trying to pass off innumerate argument as reasoning and enter the modern age.

      --
      Blasphemy is a human right. Blasphemophobia kills.
    3. Re:I don't see the problem. by Hatta · · Score: 2, Informative

      I think you're misapprehending the controversy here. One side says "This data shows that neutrinos affect radioactive decay, which is a problem for physics", the other says "That data doesn't show what you think it does, so there's no problem for physics". Nobody except you is saying "neutrinos affect radioactive decay, but it's not a problem for physics".

      --
      Give me Classic Slashdot or give me death!
  9. Re:at least we know the answer by harlows_monkeys · · Score: 2, Funny

    A friend from college got into considerable trouble as a kid when he asked that question in Catholic school, although he rephrased it slightly. His form was "Can Jesus make a dildo so big He can't shove it up His ass?" The Nuns showed no interest in discussing the philosophical aspects of that question.

  10. The Up side by Artifakt · · Score: 4, Interesting

    Variability in half life/decay rates is unlikely, and this data is not nearly enough to prove a significant effect. Because of the massive amount of research done on radioactive decay as part of various nations bomb making projects, looking for ways to get a hyper-fast reaction with less material or get criticality at all from some borderline case substances, this data would have to be supported by a quality new major research project to be taken at all seriously. Probably, the study would have to get a similar 33 day cycle for the same isotopes as these reports, AND find the same cycle for a bunch of others, AND rule out some of the possible alternate causes by doubleblind testing.
            If that's done by some place such as MIT or one of the national labs, and the data glitch persists, then it starts counting as very significant. For just one reason, Supersymetry theories predict short lived supersymetric particles such as the Selectron and the Sneutrino. The supersymetric versions of particles have substantially more rest mass than the regular versions. Neutrinos that couple more strongly to neutron cross section of a nucleus could arguably actually be Sneutrinos. To live long enough to cross the 8 light minute gap between Earth and Sun, they would have to be moving at incredibly close to the speed of light, much more so than for regular neutrinos, which are already very close (around 99.0%). Somewhere around 99.97% of C, you get enough time dilation on Sneutrinos that they could routinely make it across the gap.
            So, solar emission models for this effect could be predicting both a way to experimentally validate Supersymetry AND the existence of a reaction deep inside the solar core that produces such incredibly energetic particles. Furthermore, you could derive the energy of the initial solar reaction by sending a space probe outward towards Mars and perhaps beyond, and having it run constant testing on a radioactive isotope sample on-board to see if/when the effect falls off. Such an experiment could be incorporated into an existing planned mission, say another Mars Observer or Cassini to Saturn style probe.
            That's why this is interesting - it may be a 10,000 to 1 longshot, but a. If it's true, it's a major step for both subatomic physics and astrophysics, and b. if it's true, it makes some predictions where we can do further experiments and refine the theories, and some of these should be in a reasonable cost range compared to alternates (such as building a particle accelerator from the Earth to the Moon to possibly get a little closer to proving/disproving Supersymetry).

    --
    Who is John Cabal?
  11. Upholds One Tenet of the Media by michaelwv · · Score: 4, Insightful

    Upholds the one tenet of press releases about science: The extreme bias toward "revolutionary" things means an extreme bias toward reporting about the things least likely to be true.

  12. Re:Occam's Razor by Red+Flayer · · Score: 3, Funny

    Sturrock got old, went crackpot. Happens all the time, even to Nobel-prize winners. Check out Josephson or Weber.

    I think what you mean to say is that you have observed an unexplained increase in the rate of mental decay in those scientists, and that further study is warranted.

    --
    "Trolls they were, but filled with the evil will of their master: a fell race..." -- J.R.R. Tolkien on Olog-hai
  13. well known crackpot area by bcrowell · · Score: 4, Informative

    This idea that decay rates depend on environmental factors is well known as a fertile field for crackpots. Here's a FAQ I wrote about it.

    FAQ: 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.

    Jenkins and Fischbach claim to have observed effects on alpha decay rates 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. Their latest claims, in 2010, are 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.

    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.

    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
    Jenkins and Fischbach (2009), http://arxiv.org/abs/0808.3156
    Jenkins and Fischbach (2010), http://arxiv.org/abs/1007.3318
    Cooper (2009), http://arxiv.org/abs/0809.4248
    F. Cardone, R. Mignani, A. Petrucci, Phys. Lett. A 373 (2009) 1956
    Ericsson et al., Comment on "Piezonuclear decay of thorium," Phys. Lett. A 373 (2009) 1956, http://arxiv4.library.cornell.edu/abs/0907.0623
    Ericsson et al., http://arxiv.org/abs/0909.2141