[dylan604]

I think Super-K is the place with water so pure that it will leach pretty much anything which was discovered when one of the tech's hair got wet while leaning over the water. The hair looked bleached after it went into the water. My googlfu is not finding anything to confirm though

[pbhjpbhj]

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 the lines, Marjorie Balazs appears to have made a career out of UPW; she says in that paper:

"The ability for UPW to absorb and dissolve or react with all kinds of materials complicates other aspects concerning its use in the processing of wafers."

Seems like UPW dissolves anything, so lends credence to the anecdote.

Interesting topic, hadn't thought about UPW for wafer fabrication before.

[dylan604]

I found the article I was trying to remember:

https://www.businessinsider.com/super-kamiokande-neutrino-de...

[mock-possum]

> when travelling through water, neutrinos are faster than light

Interesting, how could this be possible?

[tefkah]

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!

[IAmBroom]

This is the way: faster than the local speed of light in water.

[gus_massa]

[I was going to write an explanation, but these sentences of Wikipedia article ar better.] From https://en.wikipedia.org/wiki/Super-Kamiokande

> A neutrino interaction with the electrons or nuclei of water can produce a charged particle that moves faster than the speed of light in water, which is slower than the speed of light in vacuum. This creates a cone of light known as Cherenkov radiation, which is the optical equivalent to a sonic boom. The Cherenkov light is projected as a ring on the wall of the detector and recorded by the PMTs.

[ars]

You aren't finding anything because it is not true. Ultra pure water does not become some kind of solvent.

It's the reverse problem: because the water is so pure it easily gets contaminated by minor things. So all the equipment has to be carefully cleaned.

[dylan604]

Water is a solvent. Not sure where you get that it's not.

From the closing of the first graph in the Wiki for water: Due to its presence in all organisms, its chemical stability, its worldwide abundance, and its strong polarity relative to its small molecular size, water is often referred to as the "universal solvent"

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

Edit: after enough searching I was finally able to find this article [0] that I was originally trying to find. The leaching part was right, but the bleaching part looks to have been as misremembered

[0] https://www.businessinsider.com/super-kamiokande-neutrino-de...

[ars]

You misread what I wrote. Water is the same solvent as both regular water and ultrapure, I was replying to the ultrapure part.

Also: I appreciate you found a source, unfortunately it's not true what they said. It's not possible to "leech nutrients through the hair to the scalp", the wrench story is not true either - there is zero chance a lab with the standards they have would just leave a wrench at the bottom of the pool - it would contaminate the water. Not to mention the bottom is filled with more of those light tubes, so there is no place for a wrench to sit. (And if someone dropped one it would break a tube.)

I don't know why someone would tell businessinsider such stories, but they are not true.

And see: https://chemistry.stackexchange.com/questions/7467/is-pure-w...

It's hard when a supposedly reliable news place writes things that are not true, but that's the world we live in. I guess technically they are just quoting stories they were told.

(My personal pet peeve is a news source that made everyone think you can't leave eggs outside the fridge if they were washed, (as they are in the US). This is not true, but "there's a news source".)

[IAmBroom]

I think people might be confusing ultra-pure water with "DI water" (deionized water).

DI water is AN AMAZING SOLVENT. Waaay more powerful at dissolving low-solubility solids than tap water, or even distilled water. It's stunning IRL to see how much better it cleans optical surfaces, where single-molecule layers can visibly change the appearance.

But if left open to the atmosphere, as in these pools, it would soon be just plain old (pure) water. Ultra-clean, but not an ultra-solvent.

[hi41]

Reminds me of the scene in Kung Panda 1 where one feather of the goose, Peng, falls into the tunnel which Tai Lung uses to unlock his cage and escape.

[hinkley]

Isn’t that also the one where a sensor imploded and caused a chain reaction that destroyed like a third of the other sensors?

[magicalhippo]

Yes, except about half. This[1] article goes into how and why, without the fluff.

The chain reaction escalated uncontrollably, and within ten seconds, approximately 6,800 of the 11,129 PMTs were destroyed.

[1]: https://physicscommunication.ie/neutrino-detector-in-peril-t...

[hinkley]

Cavitation is a bastard.

I wonder if the successor has any pressure buffering built into the design to absorb pressure waves or if they're just gonna make them 1) stronger or 2) fail more gracefully (it's okay if a sensor crumples as long as it doesn't implode)