I have been nerdsniped into building cherenkov counters for cosmics. The first three raidators are done, with two more to follow. They're just distilled water with a bit of fluorescent dye, because the PMMA window blocks strongly below 400-ish nm, so I'm trying to shift that part of the spectrum into VIS.

The two flashlights are 365 and 405 mn, demonstrating that only one results in a lot of VIS output, while the other is mostly blocked.

@gigabecquerel where are these nice cans from?

@f4grx Those are regular paint cans, you can get them in every hardware store

@gigabecquerel thats cool, hacking hardware store stuff for cool science is always satisfying.

(The hw stores in france only sell paint cans that are full, but never empty)

5 radiators are done, and three of the PMT caps are printed. They still need a graphite coat and a top plate with the connectors, but they nicely show the size of the entire detector.

Unexpected issue: Apparently the bottom seams of the cans is rusting, showing a dark brown line. Here's hoping it's just a surface thing and the cans won't rust through any time soon.

Speaking of soon, the PMTs for this should arive next week!

@gigabecquerel is it not just discoloration where the bottom has been welded in. At least. It looked welded in the pic o.o

@Jencen Nah, it's all crimped.
The fresh / dry cans have a clear line there

Motivation for this project is at an all time "meh".
The cans are rusting enough to give the water a brown tint, and DHL has managed to lose my PMTs for it.
I'm re-doing the cans with ones that have a protective coat on the inside, and while I'm at it I'm also switching to 2.5l.
I ordered the PMTs from austria via eBay, and apparently I got someone elses package. which somehow ended up with my address sticker.
DHL says it's post.at's problem, and post.at tells me to go to DHL.

Fuck off.

Yum, soup.

I ordered bigger cans thst have a coat inside. I'll also add another coat of spray paint and then test one for a week, to see if it will hold water without rusting through.

The seller was kind enough to send another set of PMTs, so we might actually be on am upwards swing here!

Speaking of inside coat, I have decided to coat the inside in fluorescent laquor as a WLS.
Here's hoping it has a fast decay, but I have not measured it.

Wheeeee

Sidequest:
Glass cherenkov counter!
I may have overdone it a bit with this order, and two glowy friends also found their way into the package.

Wrapped in plastic

@gigabecquerel caustics.3ds

@gigabecquerel this is so beautiful that it's a shame to have these mounted in light tight enclosures so you wont see them again :(

the kind of stuff I would buy in quantities of 2 each despite the price!

@f4grx At 20 € for the big cylinder it would be a bit much to just have sitting around, but I'll be honest, the cube is just for that.

Have a look around in that shop, it's all a lot cheaper than expected:
https://www.glass-sphere.com/en/index.html

@gigabecquerel Welcome to the world of glass spheres

OK they know how to speak to me.

Just to make sure I'm not the only one with this song stuck in my head now:

https://chaos.social/@gigabecquerel/115974702375905737

First big radiator built!
If that one doesn't rust I'll build two more.

@gigabecquerel Big blue bucket beaming brightly.

Sidequest: Complete ✅

It counts!
Fun experiment: Integrating what I assume to be single electron pulses gives me 33 pVs (into 50 ohm) or 650 fC. That's 4*10^6 unit charges, and for a spec gain of 3*10^6 on this PMT I'll call that close enough 😁

Using that value as a reference I can trigger on 30-ish Photoelectrons, giving me just under one trigger per second, just what you'd expect for muon flux through a detector this size!

@gigabecquerel please figure out how to build a detector around scintillator frog

Also, oh my god.
My scope apparently shows integrated voltages not as Vs, but as Wb, meaning Weber.
Yes, technically that's the same base units, but Weber is used for magnetic fields. Might as well say Tesla-square-meter there...

I let it run over night and I'm pretty sure I caught some muon decays in there!
The big pulse is a muon passing through the detector, followed by a smaller pulse due to the electron released in the decay.
The mean lifetime of a muon is 2.2 us, and while this definitely isn't statistically relevant the time distribution of the secondary pulses fits that pretty well 😂

And, of course, I'm getting some beautiful coincidences with the muon detector :)