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The physics anomaly no one talks about: What’s up with those neutrinos?

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Re: The physics anomaly no one talks about: What’s up with those neutrinos?

#21

Post by kurthr »

rpz wrote: post #14

Why do we need a particle accelerator to run experiments on neutrinos, given their apparent abundance? Is there any other way to observe neutrinos without a particle accelerator?

If everything was as expected, we don't, but the issue is that there appears to be something different about the particles coming from the accelerator (sterile neutrinos? or simply shorter distance?) since these results haven't been seen in other experiments. Of course the fact that the results could be separately replicated (and combined to give the 6sigma confidence) is another useful aspect.

If there are sterile neutrinos... they are a possible dark matter particle.

Re: The physics anomaly no one talks about: What’s up with those neutrinos?

#22

Post by [deleted] »

ncmncm wrote: post #7
hprotagonist wrote: post #2

The probable boring answer, mentioned near the end, is that at a detection rate of 500 events per 15 years of experiment runtime, statistical power comes slowly.

But, as noted, that already happened . Six sigma is six sigma. To demand better than that amounts to special pleading. It looks like people just wish this would go away, like the failure of the galactic rotation curves. What is strange is that this might be a place to park dark matter, catnip nowadays. Usually when this sort of thing happens in cosmology, astrophysics, or particle physics, it is because most physicis…

[deleted]

Re: The physics anomaly no one talks about: What’s up with those neutrinos?

#23

Post by gumby »

rpz wrote: post #14

Why do we need a particle accelerator to run experiments on neutrinos, given their apparent abundance? Is there any other way to observe neutrinos without a particle accelerator?

She mentions this in her transcript. First of all they aren’t as common on earth as other particles (she says “10-15 have passed through you while listening to this paragraph”. How many photons hit you in that period of time? If you can make a bunch at once (as a side effect of another high energy interaction) you can look at them in a known place at a known time.

Secondly, she mentions LSND which was a big tub of liquid that would interact with neutrinos that passed through it. Flashes from those interactions would be picked up by photo detectors (hence “scintillation”). The most famous such setup in a mine in Japan, but there are several such “neutrino telescopes”.

Re: The physics anomaly no one talks about: What’s up with those neutrinos?

#25

Post by _tom_ »

gumby wrote: post #23
rpz wrote: post #14

Why do we need a particle accelerator to run experiments on neutrinos, given their apparent abundance? Is there any other way to observe neutrinos without a particle accelerator?

She mentions this in her transcript. First of all they aren’t as common on earth as other particles (she says “10-15 have passed through you while listening to this paragraph”. How many photons hit you in that period of time? If you can make a bunch at once (as a side effect of another high energy interaction) you can look at them in a known place at a known time. Secondly, she mentions LSND which was a big tub of li…

Not "ten to fifteen", but "ten to the fifteenth"

A bit larger. :-)

Re: The physics anomaly no one talks about: What’s up with those neutrinos?

#26

Post by solidgol »

gumby wrote: post #23
rpz wrote: post #14

Why do we need a particle accelerator to run experiments on neutrinos, given their apparent abundance? Is there any other way to observe neutrinos without a particle accelerator?

She mentions this in her transcript. First of all they aren’t as common on earth as other particles (she says “10-15 have passed through you while listening to this paragraph”. How many photons hit you in that period of time? If you can make a bunch at once (as a side effect of another high energy interaction) you can look at them in a known place at a known time. Secondly, she mentions LSND which was a big tub of li…

She said 10 to the 15. 10^15

Re: The physics anomaly no one talks about: What’s up with those neutrinos?

#27

Post by tsimionescu »

ncmncm wrote: post #10
frumiousirc wrote: post #4

I'm surprised Sabine did not bring her usual drama and controversy to this one and talk about the fact that there is, shall we say, "extreme tension" between the results from LSND/MiniBooNE and those of other experiments. https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.11... The 4th figure is the money shot.

It is rare to see two-sigma results like this reported in physics. Or did I misunderstand?

There was a 2 sigma result, that has later been confirmed by a 4.9 sigma result from a new experiment with a new detector, giving now a combined 6 sigma confidence.

Re: The physics anomaly no one talks about: What’s up with those neutrinos?

#28

Post by drclau »

_Microft wrote: post #19
rpz wrote: post #14

Why do we need a particle accelerator to run experiments on neutrinos, given their apparent abundance? Is there any other way to observe neutrinos without a particle accelerator?

There are lots of experiments that do not require particle accelerators but if you want to observe neutrinos after they have travelled only a few dozen meters, you need a source at that distance.

> if you want to observe neutrinos after they have travelled only a few dozen meters

Genuinely curious here, why is the travelled distance important?

Re: The physics anomaly no one talks about: What’s up with those neutrinos?

#29

Post by icegreentea2 »

drclau wrote: post #28
_Microft wrote: post #19

Earlier quoted context omitted.

There are lots of experiments that do not require particle accelerators but if you want to observe neutrinos after they have travelled only a few dozen meters, you need a source at that distance.

> if you want to observe neutrinos after they have travelled only a few dozen meters Genuinely curious here, why is the travelled distance important?

If you want to measure neutrinos transforming, then knowing the distance to source lets to calculate rate of transformation.

Re: The physics anomaly no one talks about: What’s up with those neutrinos?

#30

Post by contravariant »

ncmncm wrote: post #7
hprotagonist wrote: post #2

The probable boring answer, mentioned near the end, is that at a detection rate of 500 events per 15 years of experiment runtime, statistical power comes slowly.

But, as noted, that already happened . Six sigma is six sigma. To demand better than that amounts to special pleading. It looks like people just wish this would go away, like the failure of the galactic rotation curves. What is strange is that this might be a place to park dark matter, catnip nowadays. Usually when this sort of thing happens in cosmology, astrophysics, or particle physics, it is because most physicis…

I suppose we should be a bit careful about limits like that when an experiment is run continuously, but 6 sigma is a pretty high bar to clear.
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