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Physics Girl: Super-Kamiokande – Imaging the sun by detecting neutrinos [video]

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Re: Physics Girl: Super-Kamiokande – Imaging the sun by detecting neutrinos [video]

#81

Post by wintercarver »

shadowgovt wrote: post #47

One of my favorite bits of astrophysics trivia is that the neutrino detection experiments serve as an early-warning system for supernovae, to allow astronomers to prioritize telescope time and swing the scopes around to see the first visible-light and radio signals of the event. This is because the electromagnetic energy of the supernova can take hours to force its way through all the star's mass to the surface when…

Can confirm - worked on Super-K as a grad student and a regular part of shift work was to go through simulated supernova alert testing. Was always kind of fun, in the lotto ticket sense (alarm goes off, review to see, ah yes, simulated test, back to shift monitoring).

Re: Physics Girl: Super-Kamiokande – Imaging the sun by detecting neutrinos [video]

#82

Post by jffry »

For a sense of how crazy 30 detections per day is: Super-K is a cylinder 41.4m tall and 39.3m in diameter [1] and neutrino flux on Earth is 65 billion per square centimeter per second [2]

The tank's cross sectional area relative to the sun depends on its relative orientation to the sun. We'll ballpark it at somewhere between its circular endcaps (Pi x ((39.3/2)^2) = 1213 square meters) and its curved cylindrical face (which, pointed right at the sun, has a rectangular cross section of 41.4 x 39.3 = 1627 square meters).

So, conservatively, the neutrino flux through Super-K's tank is 1400 m^2 x (100cm/m)^2 x 6.5e10 neutrino/second/(cm^2) x 86400 seconds/day = 7.86e22 neutrinos/day passing through the tank. Of which 30 are detected.

[1] https://en.wikipedia.org/wiki/Super-Kamiokande

[2] https://en.wikipedia.org/wiki/Neutrino (end of intro section, just before History). Wikipedia says only that the "majority" of the 65 billion flux is from the sun, so we might be off by a factor of two-ish in the worst case.

Re: Physics Girl: Super-Kamiokande – Imaging the sun by detecting neutrinos [video]

#83

Post by francislavoie »

fsh wrote: post #37
gosub100 wrote: post #32

Earlier quoted context omitted.

It's not the same photon though. The fusion happens in the core, then takes millennia for the energy to escape. During that time photons are emitted and absorbed by the atoms, until the surface emits one that finally travels to the earth in 8 minutes. Anyway that's taking you from the ELI5 to the ELI9 version. I'm sure someone on here can correct it further.

Any interaction between light and matter can be modeled as absorption and re-emission (stimulated or spontaneous) of photons. In this picture, there is not much difference between a photon traveling through the sun or through a piece of glass, and the analog makes physical sense. Since photons are massless elementary particles, they are indistinguishable and their number is not conserved. The notion of "the same phot…

Is it a "Ship of Theseus" photon? Hehe

Re: Physics Girl: Super-Kamiokande – Imaging the sun by detecting neutrinos [video]

#84

Post by burnt-resistor »

Cool for looking at the Sun, although I think SK was changed to be more specialized towards hunting supernovae. There's also sky surveys like IceCube does. [0]

And for terrestrial sources (geoneutrinos) from natural and artificial sources, there are/were efforts that could detect terrestrial reactors in operation like AGM2015. [1] Irrespective of the current geopolitical instability, I'm surprised that the IAEA doesn't have its own network of geoneutrino detectors to proactively look for proliferation concerns.

0. https://neutrino-map.science/ (ICNO)

1. https://www.nature.com/articles/srep13945 (KamLAND and frmr Borexino)

Re: Physics Girl: Super-Kamiokande – Imaging the sun by detecting neutrinos [video]

#85

Post by phendrenad2 »

roelschroeven wrote: post #11

Dianna got better sometime last year as well, just in time to fly home to Hawaii for her father's funeral (yeah ...), but she got a lot worse again later. I really hope things will keep going well for Dianna now. Props for her husband who's been incredible of taking care of her.

Aww, I was excited to see her name pop up again, thought maybe she had recovered.

Re: Physics Girl: Super-Kamiokande – Imaging the sun by detecting neutrinos [video]

#87

Post by mock-possum »

dylan604 wrote: post #74
pbhjpbhj wrote: post #54

Earlier quoted context omitted.

Ha, I had never heard of this effect despite having studied Kamiokande (well neutrinos, at least) as part of a mini-dissertation for my B.Sc. However, looking for sources relating to leaching by ultra pure water (UPW) not much turned up. I did however find on Google Scholar a paper "Ultrapure Water: friend or foe?"... which lead me to https://www.balazs.com/sites/balazs/files/2023-03/pub0039-up... . Reading between t…

I found the article I was trying to remember: https://www.businessinsider.com/super-kamiokande-neutrino-de...

> when travelling through water, neutrinos are faster than light

Interesting, how could this be possible?

Re: Physics Girl: Super-Kamiokande – Imaging the sun by detecting neutrinos [video]

#88

Post by KaiserPro »

hinkley wrote: post #61
KaiserPro wrote: post #28

Earlier quoted context omitted.

Dunno, personally I don't think its that much of my business. Sure I'm curious, but that doesn't mean I have a right, or that its a nice thing™ to publicly speculate

She’s been pretty open about it. She even touched on it at the end of this video.

She has, and I commend her choice. but that doesn't mean its good form to further speculate.

Re: Physics Girl: Super-Kamiokande – Imaging the sun by detecting neutrinos [video]

#89

Post by tefkah »

mock-possum wrote: post #87
dylan604 wrote: post #74

Earlier quoted context omitted.

I found the article I was trying to remember: https://www.businessinsider.com/super-kamiokande-neutrino-de...

> when travelling through water, neutrinos are faster than light Interesting, how could this be possible?

I didn't read the article, but it's likely they are faster than light is when traveling through that water. light can have different speeds through different media.

for charged particles (so not for neutrinos) this leads the Cherenkov radiation, often observed in the cores of nuclear reactor: https://en.wikipedia.org/wiki/Cherenkov_radiation

as to why in this case: it can be somewhat intuitive to think that photons would be forced to take a somewhat longer path when traveling through a medium they interact with a lot (water, anything with a charge) then something which is almost going at the speed of light and famously doesn't interact with almost anything!

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