Second study corroborates Sun influence on radioactive decay even deep underground.
September 1, 2012 9:59 PM   Subscribe

Sun seems to influence radioactive decay through no known mechanism. Radioactive decay is supposed to be the ultimate random process, immutably governed by an element's half life and nothing else. There is no way to determine when a single radioactive atom will decay, nor any way to speed-up or slow down the process. And now...the sun's influence has been corroborated.
posted by aleph (47 comments total) 21 users marked this as a favorite
 
Cahoots!
posted by TwelveTwo at 10:06 PM on September 1, 2012 [1 favorite]


Here's my post from when this was first reported, fascinating stuff.
posted by Confess, Fletch at 10:17 PM on September 1, 2012 [1 favorite]


The sun is a gravity well, and it expells muon neutrinos. It'd make sense for it to influence matter in starker fashion than the more commonly observed forms, like auroras and radio interference.
posted by Smart Dalek at 10:22 PM on September 1, 2012


This is so cool.
posted by phrontist at 10:24 PM on September 1, 2012


First thought: Radioactive decay proceeds through different pathways. The paper in the post focuses on gamma decay of the U-238 chain. I'd be curious to see how it affects other radioactive decay pathways, if it doesn't affect other pathways, then that could give a clue as to how the mechanism works.

Second thought: The paper does put neutrinos forward as a possible candidate, but only because they: A) Can pass through the Sun's outer layers without being absorbed, and B) Can be modulated by processes inside of the Sun. However, all they've got going for them is mass and a whole shitload of velocity. They pretty much only interact with anything via the weak force, which is also the force governing radioactive decay, so...maybe this is some kind of new and cool weak interaction? Maybe it's some kind of massive interaction, the neutrinos providing just enough mass/energy to destabilize a nucleus? Maybe it's dark matter? All different kinds of exciting thoughts!
posted by Punkey at 10:36 PM on September 1, 2012 [3 favorites]


This is cool. Out of pure curiosity: what *do* neutrinos do when they interact with matter? In particular, if I had a neutrino blaster and ramped it up to (nearly)-infinite intensity, what'd happen to the matter getting blasted by it?

I get that they ordinarily pass through everything and only *rarely* interact; I'm just curious about how that interaction looks if amplified to (unrealistically) large scale.
posted by hoople at 10:41 PM on September 1, 2012


Neat!
posted by Tell Me No Lies at 10:47 PM on September 1, 2012


what *do* neutrinos do when they interact with matter?

You think it's a coincidence that a major figure in cold fusion had to pass away before they could make this announcement?
posted by Tell Me No Lies at 10:49 PM on September 1, 2012 [2 favorites]


Yes, as a currently drunk and always curious layman, can someone qualified tell me: what could be the expected consequences of a neutrino flux localized on say, an adorable bunny as it increased from from the expected background levels to infinity?
posted by [expletive deleted] at 10:55 PM on September 1, 2012 [1 favorite]


This iron clad certainty has always been the best argument of opponents to conventional nuclear fission power generation, as it means that the inevitable nuclear waste will have to be kept isolated from the biosphere for million of years

What the hell was that?
posted by benito.strauss at 11:19 PM on September 1, 2012 [1 favorite]


benito.strauss: I believe it meant the accepted idea that there was no way you could affect "natural" radioactive decay so radioactive waste had the given lifetimes. This new result opens the possibility of doing something to speed up radioactive decay (how? who knows) and therefore "poof" making radioactive wastes disappear. Or something like that.
posted by aleph at 11:27 PM on September 1, 2012


Here's my post from when this was first reported, fascinating stuff.

Maybe I'm missing something but what do results about the expected strength of the magnetic field component of light have to do with a seasonal and diurnal variation in the rate of nuclear decay of various elements? Also, your post is from last year but the first paper linked to in the blog post in the OP is from 2008.
posted by XMLicious at 11:33 PM on September 1, 2012


Sunshine on my isotope makes me happy.
posted by isopraxis at 12:22 AM on September 2, 2012 [4 favorites]


For anyone chasing more recent references, a 2012 paper (DOI) by many of the same authors has a useful summary of the current state of play, which seems to be "us vs. the rest of the world":

"In a recent paper [1], early data from a sample of 137Cs on board the MESSENGER spacecraft en route to Mercury were analyzed to set limits on a possible solar influence on nuclear decay rates. This work was motivated by the suggestion put forward in a recent ser- ies of papers which cite evidence for a drop in the count rate of 54Mn during a solar flare [2], for a correlation between decay rates of various isotopes and Earth–Sun distance [3–12], and for period- icities in decay-rate data associated with solar rotation [13,14]. Although the suggestion of a solar influence on nuclear decay rates has been challenged by the apparent absence of decay anomalies in some isotopes that have been studied [15–17], and by a recent reactor experiment [18], there is no a priori reason to assume that all isotopes should be equally sensitive to a putative solar influence..."


[1] E. Fischbach, K.J. Chen, R.E. Gold, J.O. Goldsten, D.J. Lawrence, R.J. McNutt, E.A. Rhodes, J.H. Jenkins, J. Longuski, Astrophys. Spa. Sci. 337 (2012) 39.
[2] J.H. Jenkins, E. Fischbach, Astropart. Phys. 31 (2009) 407.
[3] J.H. Jenkins, E. Fischbach, J. Buncher, J. Gruenwald, D.E. Krause, J.J. Mattes,
Astropart. Phys. 32 (2009) 42.
[4] E. Fischbach, J. Buncher, J. Gruenwald, D. Javorsek II, J.H. Jenkins, R.H. Lee, D.E.
Krause, J.J. Mattes, J. Newport, Spa. Sci. Rev. 145 (2009) 285.
[5] D.E. Alburger, G. Harbottle, E.F. Norton, Earth Planet. Sci. Lett. 78 (1986) 168.
[6] J. Siegert, H. Schrader, U. Schötzig, Appl. Radiat. Isot. 49 (1998) 1397.
[7] E.D. Falkenberg, Aperion 8 (2001) 32.
[8] A.G. Parkhomov, Int. J. Pure Appl. Phys. 1 (2005) 119. , .
[9] Y.A. Baurov et al., Mod. Phys. Lett. A 16 (2001) 2089;
Y.A. Baurov et al., Phys. At. Nucl. 70 (2007) 1825. [10] K.J. Ellis, Phys. Med. Biol. 35 (1990) 1079.
[11] S.E. Shnoll et al., Phys. Usp. 41 (1998) 1025;
S.E. Shnoll et al., Phys. Usp. 43 (2000) 205.
[12] V. Lobashev et al., Phys. Lett. B 460 (1999) 227.
[13] P.A. Sturrock, E. Fischbach, J.H. Jenkins, Solar Phys. 272 (2011) 1.
[14] E. Fischbach, J.H. Jenkins, J.B. Buncher, J.T. Gruenwald, P.A. Sturrock, D. Javorsek
II, in: V. Alan Kostelecky ́ (Ed.), Proceedings of the Fifth Meeting on CPT and
Lorentz Symmetry, World Scientific, Singapore, 2011.
[15] E. Norman, E. Browne, H. Shugart, T. Joshi, R. Firestone, Astropart. Phys. 31
(2009) 31.
[16] P.S. Cooper, Astropart. Phys. 31 (2009) 267.
[17] J.C. Hardy, J.R. Goodwin, V.E. Iacob, Appl. Radiat. Isotopes (2012), http://
dx.doi.org/10.1016/j.apradiso.2012.02.021.
[18] R.J. de Meijer, M. Blaaw, F.D. Smit, Appl. Radiat. Isot. 69 (2011) 320.

posted by cromagnon at 12:26 AM on September 2, 2012 [2 favorites]


The paper in the post focuses on gamma decay of the U-238 chain. I'd be curious to see how it affects other radioactive decay pathways

Check page 4 of the paper - they mention some corroborating data obtained by BNL, PTB and Gran Sasso using other nuclides, but I haven't tracked it down yet.

If you look at their experimental setup, you will see they are actually measuring radiation from radon daughters, produced by an amount of radium-rich ore in a sealed tank: there's lots of processes involved in generating the final signal, not just radioactive decay. Radon must be exhaled from the bulk ore and then undergo several decays until the gamma-emitting daughters reach the area around the detector to be counted. Since the counting efficiency is geometry dependent, even things like a difference in the distribution of radon daughters within the chamber could in principle account for the variations observed.

Collecting gamma spectra instead of a total gamma count would be a logical next step to better understanding this result: if this is really a solar effect on the decay process, looking at individual nuclides (presumably not all affected in the same way) could give clues to the mechanism involved.

Repeating the experiment with a sealed Ra-226 source would also be a good idea, to rule out any possible gas dynamics effect due to the presence of Rn-222 in the decay chain: the behavior of radon and dauhgters in enclosed spaces is notoriously fickle, it's not impossible that the observed variability could be due to effects such as plate-out of the daughters on some surface.
posted by Dr Dracator at 12:31 AM on September 2, 2012 [1 favorite]


This iron clad certainty has always been the best argument of opponents to conventional nuclear fission power generation, as it means that the inevitable nuclear waste will have to be kept isolated from the biosphere for million of years

What the hell was that?


It is not possible to predict when an individual atom will decay, though you can predict with great certainty the proportion of atoms within a sample that will decay over a given time. Many of these radioactive elements have half lives in the millions of years. Half life just means the period at which half of a sample will decay into something else.

Now, here comes the real difficulty:

It is impossible to predict what elements a sample will decay into. That means that every time one of these atoms decays, it is effectively hitting a random button and splitting into two other atoms whose atomic weights added together equal the atomic weight of the atom the original atom that it came from. That means, that at every "half life" of a sample, half of that sample is being converted into an atomic soup of random elements.

This is potentially very volatile because not only is the original sample radioactive, these random elements that are created in the decay process are now part of the mix and can interact (read chemically react ) with one another.

Although the newly created elements have a bias towards being less radioactive because the constituent atoms will have smaller and smaller atomic masses, they become chemically more volatile because they are now no longer made of the same element and hence are no longer in a stable chemical configuration.

It is a matter of balancing nuclear reactions in which if you have enough of a sample of radioactive material close enough together, you can create a "critical mass" which creates a nuclear chain reaction - versus - the decay process setting up a mix of atoms that can and will engage in a chemical reaction.

Finally, aside from nuclear and chemical interactions, there is the third potentially most hazardous reaction component of nuclear waste and nuclear energy - the political interaction.

Atomic power is a miracle energy. A piece of plutonium the size of a soda can can power a marine vessel to speeds well beyond what fossil fuels could push it to for a period of years - it just may be that human political systems have not become sophisticated enough to manage the engineering processes that we do generally have, to reliably foster nuclear power and maintain safe and reliable nuclear reactors whose products do not become a boon to the creation and proliferation of nuclear weapons and to maintain and safely store the waste created by that power so that it does not become a threat to the environment or human populations for tens of thousands of years or also become a factor in nuclear proliferation as an ingredient in a "dirty bomb" (a bomb containing nuclear material that does not have the critical nuclear mass necessary to create a runaway chain reaction but can irradiate large areas).

Man would I love a "Mr. Fusion" that runs on banana peels!
posted by Dr. Peter Venkman at 1:01 AM on September 2, 2012 [10 favorites]


PS. In a way, I was wrong about "balancing" nuclear versus chemical reactions. They are both a problem. Storing smaller groupings of samples can help, but then you have more containers that have to be large enough to be robust.
posted by Dr. Peter Venkman at 1:06 AM on September 2, 2012


I wonder if their experimental setup also produces solar-correlated data if they run it without any radioactive material present.
posted by flabdablet at 3:39 AM on September 2, 2012 [4 favorites]


It is impossible to predict what elements a sample will decay into. That means that every time one of these atoms decays, it is effectively hitting a random button and splitting into two other atoms whose atomic weights added together equal the atomic weight of the atom the original atom that it came from. That means, that at every "half life" of a sample, half of that sample is being converted into an atomic soup of random elements.

Is this true? I thought the decay product chains for a given starting element were well known and statistical, similar to the way half-life is statistical.
posted by DarkForest at 4:13 AM on September 2, 2012 [1 favorite]


Sad cold fact. And I loathe nuclear power. But the damage we do to the ecosystem with coal fired power plants far outweighs a hundred Chernobyls. And in the end they release more fallout too.
posted by clarknova at 4:25 AM on September 2, 2012 [4 favorites]


DarkForest - You are right. On further review, they are predictable. Thought I had a good source on this. My apologies.
posted by Dr. Peter Venkman at 4:27 AM on September 2, 2012


Is this true? I thought the decay product chains for a given starting element were well known and statistical, similar to the way half-life is statistical.

Actually there is a small probability for an unstable nucleus to undergo spontaneous fission, where the products are unpredictable, but it's practically negligible for most nuclides.
posted by Dr Dracator at 4:31 AM on September 2, 2012


Do we see this effect around nuclear reactors? A typical 1GW electrical reactor puts out 4GW thermal, and also throws out about 190MW of energy in neutrinos. Similar, are we seeing increases in the beam lines of neutrino beam experiments like MINOS and MiniBoone?

Do solar flares increase the neutrino flux? I very much doubt that, actually. Solar neutrinos come from the fusion reactions happening in the core of the sun, flares come from magnetic field line shifts ejecting plasma from the outer surface of the Sun.

Heck, are we even seeing changes in the intensity of the solar neutrino flux?
posted by eriko at 6:37 AM on September 2, 2012 [1 favorite]


This sounds very, VERY cool, and not because we could maybe use it to "cool" radioactive waste in less time. I don't care about the (short term) practical applications.

To the best of my knowledge (though IANAPP), modern physics has no mechanism by which you affect the rate of spontaneous (spontaneous, not "throw neutrons at it and break it apart like a game of pool") fission.

Finding the Higgs, I considered kinda neat, but disappointing in that it merely confirmed something we already (thought we) knew. Finding out that we had something wrong though, and so fundamental as this? Game-changer!

When science becomes nothing more than adding decimal places to well-established constants, we may as well go back to sacrificing goats to Zeus.
posted by pla at 7:14 AM on September 2, 2012 [1 favorite]


As eriko says it should be easy to test the neutrino hypothesis by artificially adding neutrinos or blocking them, while doing the experiment. (i think there are ways to reduce neutrinos such as deep underground)
posted by stbalbach at 8:41 AM on September 2, 2012


Dammit Dr Peter, you had me thinking "how was I never taught that these breakdown products are variable?!".
posted by legospaceman at 9:52 AM on September 2, 2012


"The neutrinos have mutated!"
posted by Bukvoed at 10:13 AM on September 2, 2012


When science becomes nothing more than adding decimal places to well-established constants, we may as well go back to sacrificing goats to Zeus.

I was with you up until this total non-sequitur.

Dammit Dr Peter, you had me thinking "how was I never taught that these breakdown products are variable?!".

Looks like the whole good/bad thing isn't the only thing he's fuzzy on.
posted by adamdschneider at 10:22 AM on September 2, 2012 [1 favorite]


adamdschneider : I was with you up until this total non-sequitur.

Heh, sorry, I meant that as something of a joke, but just a matter of perspective, I guess.

If we ever learn everything about our universe, if we run out of meaningful things to do... Game over, we've won, call it a day. Sure, some people will stick around just to watch the entropic clock tick down, but aside from that, why bother? :)
posted by pla at 10:43 AM on September 2, 2012


No takers on explicating the outcome of the neutrino blaster? Have they all been neutrino-blasted? I hope not, but if so, can anyone say what *did* happen to them when they got neutrino-blasted? Please?
posted by hoople at 10:51 AM on September 2, 2012


I imagine being "neutrino-blasted" would be similar to being irradiated. You'd get radiation sickness and/or cancer and die painfully. Of course, an event energetic enough to create such a huge neutrino density would vaporize you pretty much instantly.
posted by dirigibleman at 10:56 AM on September 2, 2012


Pure speculation - but neutrinos interact with matter at such low rates that a neutrino blaster would be extraordinarily inefficient. You might end up with some Cherenkov radiation.

On the other hand, we know what happens when a proton beam goes through someone.
posted by porpoise at 11:41 AM on September 2, 2012


Some good objections to paper with ties to other what he calls "kook science" work on environmental effects on radioactive decay:
posted by aleph at 11:50 AM on September 2, 2012


Didn't seem to get linked: http://science.slashdot.org/comments.pl?sid=3088305&cid=41202975
posted by aleph at 11:51 AM on September 2, 2012 [1 favorite]


I've heard about this effect on and off since the first paper came out, and this thread is definitely not the place where I'll a) figure out the brand new physics responsible or b) figure out what they did wrong on their experimental set-up. My default assumption is that there's a problem with their measurement, because that's always the default assumption when there are results that contradict the known understanding of physics (if this bothers you, and you think I'm being a physics fascist, all I can say is that crazy new results happen every month in my field; a lot of doing science is about saying "I'm not convinced, do more work." Also, in my defense, I definitely have a tendency to run after unusual new results, so I'm not terribly conservative in this.) However, as they point out, their temperature and voltage fluctuations are lagging the changing rate, so most the obvious things seem unlikely as the source.

Assuming there is an effect here (big IF), the idea that it's neutrino-induced seems a bit suspicious. They're pinning a lot on the correlation between the observed rate and the solar zenith angle. However, neutrinos from the Sun travel more or less unimpeded by the Earth; Super-K, for example, can see the Sun in neutrinos while the Sun is on the other side of the Earth at night (in fact, due to high backgrounds from down-going atmospheric muons, many neutrino detectors in that energy range only look at neutrinos coming up from the floor). There are regeneration effects from traveling through the Earth, but I didn't think they were relevant for the energies of solar neutrinos.

One possible effect (again, assuming this is real, which I don't think it is) would be atmospheric muons (and their decay products, including neutrinos). These are higher energy than solar neutrinos, and are caused by high energy cosmic rays striking the atmosphere and shattering into lighter particles, including muons. The induced neutrinos of course travel straight through the Earth, but the muons are stopped by kilometers of rock. The paper is frustratingly short on experimental design information, but I know that Israel (where it appears this was done) doesn't have any experimental sites located deep enough to block muons effectively. The muon flux varies due to many complicated factors, but one of the major ones is the height of the air-column, which of course varies on yearly basis (also, perhaps, 11-yearly, along with the solar cycle). Not sure that it tracks solar zenith angle though on a daily basis, and I didn't find an answer after some cursory searching, so I'm just spitballing here.

One way to test this would be to borrow some techniques from the dark matter direct-detection people, who build their devices with active muon vetos. They put detectors around their detectors to look for incoming muons, so when they see one pass through, they can ignore any signal from their dark matter detector (which can been spoofed by muons). Here, you could either do the same thing, or just use the muon flux measurement to isolate a possible causal agent (if you don't want to assume that the supposed "induced decay" is immediate after the passage of a muon).

stbalbach, there's no way to shield from neutrinos, as they can pass through light-years worth of lead with <~ 50% chance of interacting. Deep mines are used to shield from charged cosmic rays, such as the muons I mentioned above. The neutrino background is irreducible, though the radiation from neutrino beam sources can be mitigated via distance. For example, in proposed muon collider experiments, there would be a "neutrino kill zone" around the beam due to neutrino radiation actually being higher than the allowed government levels (once the small absorption cross section is taken into account). All this means is that you have to be further away, which reduces the dose by 1/r^2.

pla, finding the Higgs is just the beginning. There were competing theories (such as technicolor) that have now been pretty conclusively ruled out, so it's not as if this was the only game in town, and our understanding of the Universe is growing as a result of the measurements from the LHC. I think we're a long ways away from the end of physics.

For using neutrinos to kill bunnies; it'd be very energy-inefficient. Elastic scattering cross-sections for 1 GeV neutrinos on protons is about 10^-38 cm^2, compared to 10^-26 cm^2 for proton-proton scattering. That is, a neutrino sees proton as a target 10^12 (one trillion) times smaller than the target size for a proton to hit another proton. The cross section drops with lower neutrino energy (it goes like the energy E).

Effectively, this means that you'd need about a trillion times as many 1 GeV neutrinos to give a bunny cancer (or kill it outright) as you'd need if you were using nucleons. How many that is turns out to be a bit of complicated problem, as the biological response to radiation is really poorly understood. I'm not going to do the numbers here, because I should be doing real work instead. The short version would be (in order of increasing intensity): cancer, radiation sickness, radiation burns, cooking the bunny, setting the bunny on fire, then ionizing the burning remnants of the bunny.

Also, who picked a bunny? that's just mean.

Finally, if reducing long-lived isotopes is your goal, then you should be looking at MeV-neutron beams, which can induce fission in normally non-fissionable elements. One use is possibly in thorium reactors, but getting rid of fission waste is another. There is a lot of engineering and science that would be needed to get this to work, but it is being talked about at Fermilab (and probably elsewhere).
posted by physicsmatt at 12:15 PM on September 2, 2012 [22 favorites]


Thanks, as always, physicsmatt. Didn't know about MeV-neutron beams, cool => off to look.
posted by aleph at 12:40 PM on September 2, 2012


MetaFilter: cancer, radiation sickness, radiation burns, cooking the bunny, setting the bunny on fire, then ionizing the burning remnants of the bunny.

no, really, that was a great comment, physicsmatt, thanks.
posted by TheNewWazoo at 12:46 PM on September 2, 2012


Aww, MeV neutron beams don't seem to be generated except from fusion reactions. A very limited source. Was hoping there was way to do that in particle accelerator that I hadn't heard of.
posted by aleph at 2:02 PM on September 2, 2012


Though they don't say what the energy of the Neutrons being generated from spallation targets they can generate neutrons.
posted by aleph at 2:10 PM on September 2, 2012


aleph: It's actually easy to do. Shoot a GeV proton beam (such as from the main injector of any particle accelerator) into a beam dump (i.e. the wall). Out the other side you'll get a beam of crap, including neutrons. The earliest canonical design for such a reactor that I'm aware of is found in "Conceptual design of a fast neutron operated high power energy amplifier" C. Rubbia et al (CERN/AT/95-44 (ET)), but there has been a lot of work done since then (some of which has been posted to Metafilter, I recall).

...and I misremembered the neutron energy you want, it's 100's of MeV, not MeV.
posted by physicsmatt at 2:10 PM on September 2, 2012


Ah. Not the fusion neutrons then. I'm fascinated by possibilities of using synchronous ultra-cold neutrons in diffraction or lensing effects. IIRC, there was some work of using cut-outs in a large crystal of silicon (like a boule for IC processing) to introduce deterministic phase shifts in a neutron beam.
posted by aleph at 2:17 PM on September 2, 2012


I'm actually an advocate for the science Jenkins et. al. are doing, without entirely understanding it. I'm not a scientist but an engineer who works on spacecraft. I feel like the Applied Physics Lab, where i work, was (is?) in a somewhat unique position to have provided experimental support to their work. We sent a spacecraft towards Pluto (New Horizons) and are working now on one headed close to the Sun (Solar Probe Plus). But the instrument selections for these NASA missions are very tightly competed, and if something is not part of the science objectives, it's difficult to get any kind of consideration.

I invited Jenkins to visit - tragically his visit fell on the worst snowstorm to hit the Lab in several years. At least he got to speak to the MESSENGER people while he was here. I'd tried to get him a slot speaking at the Friday seminars that go on here but the people in charge of that felt what he's doing is 'not appropriate', which I thought was close-minded and a bummer.

There's definitely a chicken-and-egg issue in that the theory needs to attain a degree of acceptance in order to gain access to more resources for experimental work.
posted by newdaddy at 3:34 PM on September 2, 2012 [1 favorite]


aleph's Slashdot link above seems to have evaded notice. It's a pretty serious (it seems to me) dismissal of the "rate of nuclear decay dependence on environmental factors" idea, with references to previous relevant work...
posted by talos at 4:28 PM on September 2, 2012


They were an unlikely group of MIT undergrad misfits, suffering from crushing student loan debts and unfulfilled ambitions.

He was an alcoholic MIT professor, emotionally crippled by a recent divorce, looking for meaning in a random and senseless world.

Together they would like, use their sciency sun skills to like, predict lottery numbers somehow using crazy calculations and shit, and they get rich and invent some other cool thing. Maybe Star Trek replicators, ushering in a new era of abundance and human prosperity in which wealth and possession become obsolete.

Because random article of unknown accuracy I googled just now and MIT peeps are smart and shit.
posted by lordaych at 9:42 PM on September 2, 2012


That was a really bad lazy google turd, this is more relevant, and this is where I first learned that radioactive decay is used in some random number generators:

How are lotto drawings held?
The numbers are drawn using a random number generator based on quantum vision technology. Quantum vision technology basically means the computers use decaying radiation as part of the random generation process instead of a computer chip.
posted by lordaych at 9:46 PM on September 2, 2012


The comments from the article page are pretty good, especially since John Baez pops in to police what he claims is personal imaginative speculation about general relativity (on the part of another commenter) rather than any real scientific theory (real as in held by any scientists).
posted by TreeRooster at 7:14 AM on September 3, 2012


I wrote about this when it showed up here before (which is probably what Confess, Fletch was trying to link to early in the thread).

I can't really tell what's new here. There are lots and lots of things that could cause annual and sub-annual variation in the performance of a detector. Mysterious radiation from the sun is way, way down the list.
posted by fantabulous timewaster at 10:51 PM on September 3, 2012


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