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What could explain the gallium anomaly?

quantamagazine.org

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Re: What could explain the gallium anomaly?

#81

Post by tlogan »

d_silin wrote: post #78
tlogan wrote: post #76

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…

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

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 ...

Re: What could explain the gallium anomaly?

#82

Post by aw1621107 »

keepamovin wrote: post #60

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 sophist…

> 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

Re: What could explain the gallium anomaly?

#83

Post by justinator »

lazide wrote: post #65
justinator wrote: post #64

Earlier quoted context omitted.

Tsar Bombas aren’t realistic weapons. Russia is having trouble producing modern tanks and planes. Its ships are being blown up by radio controlled boats with explosives on them. Russia absolutely excels at one thing: the relentless use of its human meat grinder. Nothing fundamental has changed since Stalingrad.

Russia also excels at MAD. And suffering.

Suffering yes -- to an extend that we here in the US have little understanding the depths of.

But re: MAD, my point may have been the emperor's new clothes.

Re: What could explain the gallium anomaly?

#84

Post by eigenket »

tlogan wrote: post #81
d_silin wrote: post #78

Earlier quoted context omitted.

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

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 ...

The known (non-sterile) neutrinos are very light, but there's no particular reason a hypothetical sterile neutrino would be.You can cook up sterile neutrinos with very large masses if you want to

https://arxiv.org/abs/1303.6912

Re: What could explain the gallium anomaly?

#85

Post by alleztarmac »

keepamovin wrote: post #60

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 sophist…

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.

Re: What could explain the gallium anomaly?

#86

Post by jfengel »

krick wrote: post #79
jfengel wrote: post #70

Earlier quoted context omitted.

Our government is doing some terrible things. I voted for this government and I feel I should take some responsibility for it. I accept that there may be consequences, potentially awful ones. I am afraid we are about to vote in a government that will do even more harm -- including to me personally. I think that a lot of people are choosing that harm deliberately. But even worse is a lot of people who are willing to a…

Did you ever consider that USAians are not really a democracy and their understanding of the world is severely warped by their media? It is 100% true, by the way.

Of course. But I'm as certain as I can manage (in an epistemologically challenging world) that we're closer to those goals than Russia is.

I'm not especially interested in false equivocation as an argument. It's cheap and boring.

Re: What could explain the gallium anomaly?

#87

Post by raattgift »

d_silin wrote: post #78
tlogan wrote: post #76

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…

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

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...

Re: What could explain the gallium anomaly?

#88

Post by dmurray »

gus_massa wrote: post #69
qnleigh wrote: post #50

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?

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…

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?

Re: What could explain the gallium anomaly?

#89

Post by paganel »

geuis wrote: post #45
bawolff wrote: post #29

> 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.

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 s…

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.

Re: What could explain the gallium anomaly?

#90

Post by timcobb »

TeMPOraL wrote: post #72
timcobb wrote: post #57

Earlier quoted context omitted.

Living in the world as a hostage to nuclear weapon yielding crazies is a fate worse than death for some free-minded people.

Shame about those free-minded people; everyone else understands that it's how the world works and why everything isn't on fire. MAD is the foundation of international politics; everything else is role-playing on top of it.

> MAD is the foundation of international politics

MAD is a religion-like fiction by-for people who emotionally need it. People armed with nuclear weapons are coming for us, whether it's emotionally convenient for you or not. And it doesn't matter whether we have nukes, too.

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