Notices by gigabecquerel (gigabecquerel@chaos.social), page 4

The RPC is coming along nicely!
Still missing its linseed oil coating and the pickup strips, I decided to go with a 1-Dimensional readout for now to make things easier. These detectors are so simple, I can just make another one and use that in 90° to this one!

Well, all the gas connectors and stuff are ordered and a second RPC is glued up, now all I can do is wait.
Once everything gets here I can oil both at once and polymerize them at the same time

Oiling went terrible (thanks leaking connectors from ebay) but now they're oiled and will be pumped with air for the next days or weeks or however long it will take.
Hope the vastly inconsistent oil speed won't cause any issues, but we'll see

Small side project:
A jig for measuring bulk resistivity!
I'll finish it tomorrow, then the function will become more apparent as well.

Damn, that's the perfect angle to show any defects in my prints 😅

Damn, it came out perfect!
This glass tile has a resistivity of 1.6*10^13 Ohm*cm, which agrees perfectly with literature for generic glass 😁

over night test confirmed FeCl3 etches off copper but does not attack NbTi

And here, finally, is the ADR itself.
At this point I was pretty tired and forgot to take pics of the good stuff :<
You can see the two stages hanging on kevlar threads, the entire assembly would be sitting inside the magnet bore in its original position.
The stainless tube is the second ADR stage, consisting of ferric ammonium sulfate. This salt is slightly hygroscopic, and through years of storage it accumulated water which caused it to swell.

I think that's all for now, but I'm sure I forgot something. If you have any questions feel free to ask!
I'm sure there will be more images of everything, especially the magnet, as we want to take it apart to get to the NbTi wire.

the magnet is doing its best not to come apart in one piece.
They used the *good* resin, as well as way too much glass fiber reinforcement.
At least too much to be any fun when taking it apart again.

I took some SEM shots of the wire, and you can kinda see how it's NbTi embedded in a copper matrix, but to be honest, I was hoping for way more contrast with the SE detector.
BSE is broken, and EDX is in the works...
Maybe @breakingtaps has any tipps?

Better sample preparation should do the trick.
Casting two pucks of epoxy with the SC wire in all directions, one to be etched, one to be left as is after polishing.
Now comes the hardest part, waaaaaaiting

Woooooot it worked so well!

@jmorris @stdlogicvector Never seen one before, and no, it does not need ³He, just regular LHe

Science is cool!
And this thing here even more so.
I got to take apart an Adiabatic Demagnetisation Refrigerator Cryostat with the wonderful @stdlogicvector , a small cryostat that was used to cool a transition edge sensor to ~40 mK.
It works by applying a magnetic field to some funny materials, and when removing that field the material cools down below its original temperature, which is 4.2 kelvin in this case.
The main cooling is done by a huge amount of LN2 and LHe.

There was some kind of experiment left over in there, I'm guessing it's a remnant of the CRESST experiment, a crystal, a collimator and a photodiode, so maybe scintillation yield measurements?

The entire cryostat consists of an LN2 tank which provides heat shielding and a LHe tank as a "warm" stage. The bottom of the LHe tank forms the base plate and thermal anchor where everything is bolted onto. Inside the tank is the ADR Magnet which we'll get to in a minute. Inside the magnet bore, held by kevlar strings, is the ADR itself. Everything is wrapped in foil for thermal insulation.

This is the thermal switch. It links the ADR thermally to the 4k stage when everything is being cooled down and while the magnet is being ramped up. Then the switch opens, separating the ADR themally and letting it cool down below 4k when the magnet is ramped down again.

The cryostat coinsists of many layers, it's built like an onion.
This serves to reduce thermal load vial radiation, with the 77k stage sinking the biggest load, after all, LN2 is a lot cheaper than LHe.

This is the magnet itself. As stated earlier it's entirely submerged in LHe to cool it down, afaik it's NbTi used at up to 7 T. It has to be in LHe because its critical temperature is around 10 k.
Interestingly enough it consists of two separate windings with entirely different construction! Maybe one was added later for higher fields, but I don't know

@TechConnectify It's pouring outside, and this is what you made me get!

Stadtbegrünung any% speedrun
Wird sicher richtig angenehm im sommer, jetzt, wo nichtmehr überall schwarzer Asphalt ist.
Wie wärs noch ein paar plastikbaumimmitate da hin zu stellen?
Sicher kann man da noch irgendwas einbauen um mehr geld zu verdienen.

Schön immer wieder zu sehen was für ein drecksloch diese stadt doch ist.