What could explain the gallium anomaly?

https://www.quantamagazine.org/what-could-explain-the-gallium-anomaly-20240712/

by ars • 2 years ago

215 102 2 years ago

CamperBob23• 2 years ago

Photo caption: In the lab that houses the BEST experiment, fish serve as an early warning system about any leaking radiation.

Never change, Russia. Never change.

dylan604• 2 years ago

You can't get them all right. To be fair, they used pencils while NASA spent time and money to have a pen that writes in 0g.

spankalee• 2 years ago

That's just a myth, you know: https://www.scientificamerican.com/article/fact-or-fiction-n...

dflock• 2 years ago

Fischer made the space pen as a commercial product, all R+D entirely at their own expense. NASA just bought some of the pens from them.

Etheryte• 2 years ago

This is a myth, using a pencil in space isn't clever or thrifty, it's a disaster waiting to happen. The graphite from pencils breaks off in small fragments while writing and the fragments can create shorts in electronics and to top it off they're also flammable. None of those are properties you want to bring into a spacecraft.

mrguyorama• 2 years ago

After Fisher, the pen company, spent their own couple millions to develop a pen that could write in zero gravity, they convinced NASA to use it, and a few years later the Soviets bought 100 of them for their own space program.

NASA was never involved in the development of the space pen, though they supposedly had their own effort that was quickly abandoned as it got expensive. Before that they also used pencils.

The pen is just a better writing implement in space. It cost $3 in the 60s, with wide availability.

sterlind2• 2 years ago

coal miners carried canaries to warn of CO. chemical weapons workers brought bunnies in cages to monitor nerve gas leaks. it's an old tradition - it's simple, and it works.

though why not Geiger counters for radiation? there must be a reason.

CamperBob23• 2 years ago

If there's enough CO to kill a canary, you still have time to get to safety.

If there's enough nerve gas to kill a rabbit, you still have time to get to safety.

If there's enough radiation to kill a fish, you're a walking dead man... and the 'walking' part is temporary.

Terr_4• 2 years ago

I'm no nuclear physicist, but a theory to try out:

1. The leak scenario they're concerned about is an alpha emitter within water, which-- unlike gamma rays and Geiger counters--is harder to detect remotely, since the water serves as effective shielding for anything but microscopic distances.

2. Permanent resident fish serve as a kind of long-term accumulator for dissolved amounts that would otherwise be too hard to detect.

3. The concern isn't so much immediate risks to human health, but rather how any slow leak or discrepancy might compromise the experiment.

TeMPOraL2• 2 years ago

though why not Geiger counters for radiation? there must be a reason.

If a detector fish moves, it works. With Geiger counter, you may not be always able to tell when it malfunctions.

lossolo• 2 years ago

Did you know that mussels and clams are sensitive to changes in water quality and can absorb pollutants? They are often used as bioindicators to detect harmful substances like heavy metals and toxins in the water. They are used in United States and in Europe to check if water is clean.

hinkley3• 2 years ago

I remember someone creating a sensing system to see if the shells were open or closed. Given enough mussels, the odds of them all closing at once due to random chance instead of pollution drops to zero.

ars3• 2 years ago

Would sterile neutrinos as an oscillation really change anything about dark matter? The total mass of neutrinos doesn't change, just the lepton number.

AnimalMuppet2• 2 years ago

It might mean 20% more neutrinos exist than we think. That would change the total mass of neutrinos.

Much more interesting (and not touched on by the article as far as I noticed): The electron neutrino is the "partner" to the electron. The muon neutrino is the partner to the muon, and the tau neutrino to the tau. What's the sterile neutrino the partner to? (Or doesn't it have one, and that's what makes it "sterile"?)

If there is a partner to it, does the partner have mass? Does it interact in any way besides gravitationally? If not...

torrefatto• 2 years ago

IIRC, there is another quantum number, the chirality. All the neutrinos measured are left chiral. The sterile neutrino, which does not pair with other lepton, is right chiral.

ars3• 2 years ago

It might mean 20% more neutrinos exist than we think.

Would it though? It's not like we know neutrino mass from measurement, rather we estimate it from nuclear reactions that have occurred. The estimate would not change if a neutrino oscillates into a sterile one.

ars3• 2 years ago

What's the sterile neutrino the partner to?

It would be a very unusual partner that has no concerved quantum numbers, and only mass.

A sterile neutrino would also imply that the neutrino is a Majorana particle (because it would have not quantum numbers that could be "anti").

PaulHoule• 2 years ago

Sterile neutrinos could also be a lot heavier than regular neutrinos, those kind of sterile neutrinos are ideal candidates for explaining dark matter and the matter-antimatter asymmetry

https://arxiv.org/abs/1303.6912

Just as I am disappointed that "global warming" changed into the more ambiguous "climate change", I'm a little disappointed that the "right-handed neutrino" has turned into the "sterile neutrino". It's really strange that we only observe left handed neutrinos and either the revelation that there is a hidden right-handed neutrino or that neutrinos are fully Majorana particles without a right-handed form would be absolutely groundbreaking.

My take on it is that the neutrino mass term is not "physics beyond the standard model" but rather a "missing part of the standard model" and that one way or another, neutrinos hold an important secret, if not the important secret of the universe. (Note potentially three generations of right-handed neutrinos could exist at three mass scales and explain the gallium anomaly, cold dark matter, and the rarity of antimatter)

labster2• 2 years ago

As a climatologist, I can tell you that we switched to “climate change” because it’s more precise. “Global” in global warming is not the “universal” sense of global, because not everywhere on Earth warms equally, and some places may even cool with mean global warming. Global climate change implies that the averages and ranges are changing. The phenomenon is best measured in statistics.

(Also as a climatologist I have no idea what the handedness of neutrinos even means. Something with spin?)

Terr_4• 2 years ago

sterile neutrinos

It's funny when one encounters serious real-world discussion on something previously seen as sci-fi technobabble.

In this case, I'm thinking of the Destiny universe, such as this apocalyptic alert from a military AI. [0]

Multiple distributed ISR assets report a TRANSIENT NEAR EXTRASOLAR EVENT. Event duration ZERO POINT THREE SECONDS. Event footprint includes sterile neutrino scattering and gravity waves. Omnibus analysis detects deep structure information content (nine sigma) and internal teleonomy. No hypothesis on event mechanism (FLAG ACAUSAL). Bootstrap simulation suggests event is DIRECTED and INIMICABLE (convergent q-Bayes/Monte Carlo probability approaches 1). No hypothesis on deep structure encoding (TCC/NP-HARD).

______

In the lab that houses the BEST experiment, fish serve as an early warning system about any leaking radiation.

I'm curious how this works, it looks as if there's one central underwater valve and two above-water valves, perhaps supposedly-breathable air is getting bubbled up through the tank?

SAGE used a tank of 57 metric tons of gallium.

Some napkin-math [egregious mistake corrected] to visualize how much that is, and I get "45 oil drums".

    Line item               Amt Units
    Gallium Mass            5.70E+01    metric tons
    Gallium Mass            5.70E+04    kg
    Gallium Mass            5.70E+07    grams
    Liq. Gallium Density    6.10E+00    grams/cm3
    Gallium Vol             9.35E+06    cm3
    Oil Drum Volume         5.50E+01    gallons
    Vol Ratio               3.79E+03    gallons/cm3
    Oil Drum Volume         2.08E+05    cm3
    Gallium Volume          4.49E+01    oil drums

____

[0] https://www.ishtar-collective.net/cards/ghost-fragment-darkn...

auspiv• 2 years ago

double check that math - olympic pool is 50x25x2 meters, or 2500m3. 1 m3 of water is roughly 1 metric ton (1 g/cc = 1 kg/L = 1 t/m3) depending on temperature and such.

57000000g / 5.9 g/cc = 9661017 cc = 9.661m3

Terr_4• 2 years ago

Whoops, yeah, made a few mistakes. Next time I'll do the usual and open a throwaway spreadsheet. Also, picking gallium-density from a slightly higher temperature where it's liquid.

addaon• 2 years ago

Google is (still) a great tool for this sort of conversion. It comes up with just under 58 barrels: https://www.google.com/search?q=57+tonnes+%2F+%286.1+g%2Fcm%...

Terr_4• 2 years ago

Google is (still) a great tool for this sort of conversion

Alas, not in this case, since Google is interpreting that as a 42-gallon "petrochemical-industry traditional abstract measuring unit of crude oil" as opposed to a 55-gallon "physical container readers may have seen and everybody actually uses." (Including to hold crude oil, in the rare cases that it's not in an enormous tank or pipeline.)

Perhaps this is an example of where "intelligent assistant" software lands in a dangerous middle-zone of "wrong, but not wrong enough that it's obvious."

Anywho, if we reword it a bit and put in a less-rounded density, it comes out the same:

https://www.google.com/search?q=57+tonnes+%2F+%286.095+g%2Fc...

__________

P.S.: The way it parses this small change is also amusing, where "in water barrels" isn't a change in the type of barrel, but instead introduces a non-SI unit of pressure, making everything murky indeed.

https://www.google.com/search?q=57+tonnes+%2F+%286.1+g%2Fcm%...

easygenes• 2 years ago

My preference for this on the web is Wolfram Alpha: https://www.wolframalpha.com/input?i=57+tonnes+%2F+%286.1+g%...

(note I've slightly changed the prompt to match the "drums" OP used instead of barrels. This avoids the issue other child mentions of ambiguous units, as it clearly states the volume of drum it's using and gives options for others (e.g. the international 200L instead of the US 208L/55 GAL).

Another option which I wouldn't inherently trust to get the calculation just right, but is good for explaining the process if you can fact-check it is ChatGPT-4o: https://chatgpt.com/share/ead07fff-8d55-4147-a742-6e19b26f1e...

jessriedel• 2 years ago

> It's funny when one encounters serious real-world discussion on something previously seen as sci-fi technobabble.
In this case, I'm thinking of the Destiny universe, such as this apocalyptic alert from a military AI.

To be clear, physicists have been thinking very non-fictionally about sterile neutrinos since 1968.

bawolff2• 2 years ago

While Russia’s invasion of Ukraine “has complicated things,” Elliott said, the collaboration between the U.S. and Russia on BEST is still ongoing, for now.

Nice to hear in these uncertain times.

geuis2• 2 years ago

How is that "nice"? The fact that 3 years in we are still collaborating with Russia on the ISS and in other scientific programs is deeply disturbing. I get that the ISS is a special circumstance and a difficult knot to unravel. That's an extremely unique situation and it's not worth digging into at length for this situation. Life support onboard for all occupants relies on a continuing collaboration.

Beyond the ISS situation we should have completely cut all ties with Russia. They have killed hundreds of thousands of Ukrainians. Stolen children, assaulted women, and killed Ukrainian elderly and children. Not even digging into their internal recruitment policies, but the way they drag innocent Russian civilians into supporting their invasion is worth its own war crimes investigation.

Yes, this experiment is interesting and it's intriguing to me. But it's not "nice" when a few physicists are getting results at the expense of all the collective suffering going on right now.

I'm generally pragmatic about things, but in this situation cooperation is entirely uncalled for.

Meanwhile the US ignores joint efforts with China. They (China) have some interesting things going on right now. For an international space station, it's awful that a Chinese crew hasn't even been invited to the ISS despite allowing numerous rich folks going up for a week long vacation.

To be clear, I'm NOT supporting China. Their government is antithetical to a free society and is deeply partnered with Russia, N. Korea, and other states hostile to the EU and US.

But they are a major player in humans in space, and it's important to engage them at that level. Again, the ISS is a unique scenario.

jpgvm• 2 years ago

The problem is these joint scientific efforts were and continue to be effective tools to diffuse more dangerous possibilities.

In case you have forgotten Russia is still the 2nd largest nuclear power and their arsenal is enough to eliminate pretty much all life on Earth.

The war in Ukraine is terrible but don't underestimate how much worse things could get. If things do get worse it's back channels like space collaboration/UN/other symbolic things that can keep people talking enough to not end up cleansing the Earth in nuclear fire. Just because those things are ineffective at stopping a proxy war doesn't mean they aren't worth doing.

For the same reason I also agree that China should be welcomed into the international space community. They are flying state of the art rockets and have their own modern space station... you couple that with the fact they too are an increasingly powerful military nation then more collaboration rather than less is the way to go.

bawolff2• 2 years ago

I hate the russian regime and what its doing to ukraine too.

Still there is something comforting about putting aside our differences, petty and otherwise, to do science.

After all, its not like the Russian scientists involved personally ordered the invasion.

sho2• 2 years ago

I'm generally pragmatic about things

Not nearly pragmatic enough. Of course the war is terrible and of course Russia is to blame. But the world doesn't stop moving and high level co-operation still needs to continue. Russia is still a big, powerful, important country and we can't just cancel everything in a fit of spite.

I mean, even Ukraine, even while it's being brutalized by its neighbor, still maintains high level connections to organize prisoner transfers. There's regular communication between the RUAF and NATO to deconflict and identify each other's assets to avoid misunderstandings and accidents. All of this continues, war or not, because everyone knows the alternative is just that much worse.

It's no different for the scientific cooperation. War or not, everyone knows it is in everyone's best interest for cooperation to continue. The scientific ties long predate the war, and will continue long after everyone has forgotten it, too.

And I'm surprised you then completely contradict your moral point - which I disagree with, but it is a point - by suggesting the West engage with China, a prospect against which almost the exact same argument can be made. Of course, taking the "we only co-operate with partners with sparkling moral rectitude" line even further, you could argue that no-one should be co-operating with the USA, with its two disastrous recent wars, either. See where this goes?

bawana• 2 years ago

This project highlights the complexity of the real world. Not all of russia is evil. So why should the good be isolated, starved, punished? True, people in power can cause irreparable harm to neighboring nations, or even their own (Stalin?) Do we therefore obliterate all contributions of Soviet math, science and engineering and expunge them from our internet?

In the face of injustice caused by politicians and corporations, we must privately support those individuals doing good work.

bosco_mcnasty• 2 years ago

I see it more simplistically. If there's two guys love neutrinos, neutrinos is they passion, one happens to be born in Russia, one in US (neither one chose to be born there), and they want to work together to understand life, the universe, everything, then so what? What matters more, life, the universe, everything, or some years-long dramatic squabble, years long on the scale of a 5 billion year old planet and millions year old species and perhaps tens of thousands of years old civilization.

The "ideal" of science is that there should be this purity, this honesty, etc. Deviations do occur, politics are common in science itself, data falsification, etc, but we must not let that deny the purity ideal. In the same way, I believe the idea here is to acknowledge that purity over political differences as something transcendent to politics. But yes, such collaborations do have political value in terms of being a "relationship". And yes of course I don't want to poo-poo politics. Whereas it's true that politics is as inescapable to the human condition as say language, perhaps we shouldn't let political constraints guide and dictate scientific work just as we shouldn't let linguistic barriers limit science, both part of the human condition, both miniscule in the face of the work being done.

paganel• 2 years ago

As far as I can tell the US is fully, and I mean fully, on Israel’a side, even though the genocide now happening in Gaza is a very real thing.

chr1• 2 years ago

The fact that 3 years in we are still collaborating with Russia on the ISS and in other scientific programs is deeply disturbing.

Do you think Putin cares about scientific programs enough to stop killing people?

All the "we won't talk to Putin, but will buy Russian gas reexported by another murderer Aliyev" is very nice and emotional, but it did not have any positive effect.

If instead of all of this theater with sanctions, EU and US gave more weapons from the start, and removed regulations to drop oil prices, Ukraine would have won at the end of 2022, and at a much smaller cost than damage to the EU economy already caused by sanctions.

qnleigh• 2 years ago

Is there any reason to think that Gallium would be a particularly good source of sterile neutrinos? Or is it more that if regular neutrinos oscillate into sterile neutrinos, then this would be the first experiment that could detect so at this scale?

pavel_lishin• 2 years ago

The gallium isn't what's producing the neutrinos; there's a radioactive source that the gallium is being irradiated by, and I believe that's the source:

In an underground lab shielded by a mountain of rock, highly radioactive material sits inside a vat of liquid gallium, blasting out particles called neutrinos that break the gallium down into atoms of germanium.

gus_massa4• 2 years ago

Gallium is not a source of sterile neutrino. Gallium is a good "electonic neutrino" target.

The problem is that they only detect the 80% of the "electonic neutrino" that they expect and they have no clue of the cause. One of the posibilities is that the other 20% of the "electonic neutrinos" mutate to "sterile neutrinos" during the trip.

(Note that there are 3 types of neutrinos and it's possible that there are also a few types of sterile neutrinos (3 is a good guess).)

dmurray• 2 years ago

I'd still like to ask a version of the same question, is gallium so special that it only makes sense to do this experiment with gallium?

If sterile neutrinos cause the production of germanium from gallium to be 80% of what we thought it was, will there be other nuclear reactions that we now don't understand? E.g. a given plutonium reaction produces 100g of uranium, currently consistent with the theoretical model, after sterile neutrinos are confirmed will we be saying hang on, this should only produce 80g of uranium with the new model, something else is wrong?

Presumably not, at least with well-understood reactions, so why is gallium so special here?

jarsdel• 2 years ago

Given the potential implications of discovering sterile neutrinos, what other anomalies or unexplained phenomena in particle physics might be re-evaluated in light of this new understanding?

kseistrup• 2 years ago

A Capella Science: Massless (Muse neutrino parody): https://youtu.be/dBxcC8zV46E

keepamovin2• 2 years ago

Could the gallium anomaly be explained by something far more prosaic? For example, in water, there are all kinds of species of different anions and cations present, existing in equilibrium with each other. Water forms complex semi-crystalline structures by virtue of hydrogen bonds. Although they are not true crystals, the supramolecular structures of individual water molecules and the valence species create a sophisticated structure, even in a seemingly homogenous substance.

Now, consider if something similar happens with gallium. What if the electron configuration of gallium's orbitals means that gallium, in its liquid form, also has various anions and cations? Moreover, what if gallium can form analogs to hydrogen bonds, leading to semi-crystalline or structured forms?

This structured form could provide some shielding to the gallium atoms, making them less likely to be converted via neutrinos to germanium. Instead of impacting a nucleus at the expected rate, the overlapping orbital bonds and electron resonance might offer a form of shielding. This shielding could make the gallium atoms more stable and less reactive, thereby reducing their conversion to germanium.

While this idea applies a chemical concept to nuclear chemistry or physics, and may not align perfectly with the traditional views of high-energy particle physicists and astronomers, it offers a potentially more prosaic explanation for the gallium anomaly. This perspective might not have been top of mind for those focused on high-energy interactions and could be worth considering further.

baxtr• 2 years ago

Unfortunately many physicists believe chemistry is just applied physics. In reality most physicists have no clue of chemistry beyond the H2 molecule.

Based on that, your “less prosaic” could be a good candidate for an explanation.

aw1621107• 2 years ago

This structured form could provide some shielding to the gallium atoms, making them less likely to be converted via neutrinos to germanium. Instead of impacting a nucleus at the expected rate, the overlapping orbital bonds and electron resonance might offer a form of shielding. This shielding could make the gallium atoms more stable and less reactive, thereby reducing their conversion to germanium.

Might this be covered by this bit from the article?

Another proposed explanation was that physicists had miscalculated the probability of neutrinos from the source interacting with the gallium. But in September 2023, Haxton and his colleagues also ruled out this possibility. “You can’t get rid of the anomaly,” he said.

Maybe they don't consider the scenario you outlined in their calculations, but I lack the training to understand the paper [0].

In addition, speaking more generally I'd be curious how your proposed mechanism would work physically. Given the size of the nucleus compared to that of the electron cloud, the fact that (known) neutrinos only interact via the weak interaction and gravity, and the range of the weak interaction, a big question to me is how big your proposed effect could have in this case, if any.

[0] https://arxiv.org/abs/2303.13623

alleztarmac• 2 years ago

If I understand idea, this sounds like what physicists might call a 'collective phenomena' effect introducing some type of screening. It's possible -- if true it could independently be tested. I know there are models for this type of stuff in denser matter (and in more extreme conditions), but not sure whats known in situations like the experiment. I assume there is a reason that isnt mentioned, but would love to know from an expert why.

Collective phenomena do show up in high energy/particle physics, albeit rarely, ex: when you collide large enough nuclei together at high enough speeds, you create a highly energy-dense nuclear plasma which effective 'screens' jets of particles that would travel through the center of the collision. If you go to smaller nuclei or lower energy, you can start to see these jets of particles pass through the collision area.

gus_massa4• 2 years ago

Neutrinos can pass through the whole Earth, and almost none of them is stoped. A trick to get a neutrino ray and block all other particles is to not build a tunel and let a few miles of soil absorb all other particles. So a few electrons more or less concentrated arround a gallium atom have no effect. Considering the electronic distribution is an interesting idea, but not for the shelling effect.

This is not my area so I have to guess more than what I'm confortable. Anyway, the difference between the electons in gallium and germanium is an aditional electron in a p orbital. An electron in a p orbital has some probability of beein nearby the nuclei.

The decay from germanium to galium is an electron capture Ge + e -> Ga + ν , so the "postion" of the electon is important, but I'm not sure how important. But in this experiment they are measuring the inverse reaction Ga + ν -> Ge + e and comparing the rates of both reactions.

So ... perhaps it's possible that the change of the electon density distribution causes a change in these decay/undecay. I never heard something similar, and I expect the effect is neligible, but this is not my area so I can't rule it out.

keepamovin2• 2 years ago

Yes I understand the traditional objections to this idea. I don’t think you’ve quite grasped what I propose tho. Consider this: The reaction v_e + (71)Ga → (71)Ge + e− involves the release of an electron. The local electronic environment, including electron orbitals or metallic bonds in liquid gallium, can influence this electron's energy levels and spatial distribution. These changes can affect the reaction rate and shift the equilibrium position of the reaction, potentially making the forward reaction less favored and accounting for the 20% discrepancy. So, while neutrinos primarily interact via the weak nuclear force, the electron release means the local electronic environment can subtly impact the overall reaction dynamics.

jnurmine• 2 years ago

Gallium likes to form alloys with other metals, does this anomaly happen with the gallium-containing alloys as well?

tlogan2• 2 years ago

Question for experts:

If sterile neutrinos exist, would they be the best candidate for dark matter? Additionally, would it be impossible to detect them since they do not interact with anything and possess only mass?

EDIT:

My reasoning is as follows:

- Low-energy neutrinos might not be relativistic. For example, relic neutrinos from the Big Bang, which have a temperature of around 1.95 K, would travel at approximately 4.5% of the speed of light.

- I've also read that sterile neutrinos are hypothesized to have a large mass (though I'm not sure).

So "slow neutrino" + "not so light like normal neutrino" => dark matter

d_silin• 2 years ago

All neutrinos are relativistic (moving at almost speed of light) and our current model assumes dark matter is "cold" (moving at relatively slow speeds).

tlogan2• 2 years ago

Thank you. I updated my question with my reasoning.

But I assume that in order for these sterile neutrinos to be dark matter they need to be really slow ...

raattgift• 2 years ago

There is excellent evidence for then-relativistic cosmic neutrinos from the cosmic microwave background acoustic oscillations. As with the CMB, these neutrinos cooled into a "relic" field with the metric expansion.

A cooling gas of relativistic neutrinos becomes non-relativistic when the average neutrino momentum becomes comparable to their rest mass. The present cosmic neutrino background (CNB) temperature is about 1.9 kelvins corresponding to ~ 1.7e-04 eV/c^2 which is smaller than some neutrino masses.

This is still "hot" compared to Cold Dark Matter, and CNB also only a small fraction of the required CDM energy density.

The lightest cosmic neutrino background mass eigenstates could be relativistic at present, so how the CNB is split between (FLRW) radiation and dark matter is ripe for research. It will mostly be "hot" DM because of the heavier, colder species. But not hot enough to leave clusters of galaxies, unlike neutrinos produced by present-day astrophysics (and our own laboratory experiments and nuclear power generation).

https://en.wikipedia.org/wiki/Cosmic_neutrino_background

https://bigthink.com/starts-with-a-bang/cosmic-neutrino-back...

What could explain the gallium anomaly?

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