35ton and LAPD cryostats and future DUNE detector development

LAPD (30 ton) and 35ton cryostats ADVICE: Find a way to do your test in a smaller more nimble test stand The size of these cryostats makes filling with LAr expensive and logistically complicated (4 delivery trucks over 2 weeks for example) That means it is a one-shot test, you can’t access your stuff inside and turn knobs, then measure again. There are smaller test stands at PAB with purification systems where a small TPC can be installed in a couple weeks and filled in a couple hours. This is how/where the ArgoNeuT electronics were developed and alternate cold CMOS pre-amplifier was tested for LBNE

50 cm 30 cm

35ton: Ship in a bottle Side view Front view hallway d=4104 mm 5404 mm s=1995 mm This is a VERY awkward place to work! Confined space that requires special training and a watchman posted outside while working 35ton phase2 detector was made as big as possible, thus barely fits into the existing space. Therefore, the just-installed component blocked access to the previously installed one. 6 months from start of installation to liquid argon filling. Only 1-2 months of that was detector installation Cryo piping and pumps have to be removed for access to the tank

“Long Bo” LAPD hinge 2 m

Why would we do anything in the 35ton or LAPD? They are big inside compared to other cryogenic test stands. They share a liquid argon purification system with very large capacity and sophisticated gas analyzer system (LAPD purity was > 14ms) 35ton is the only membrane cryostat available for tests

Remember LAPD shares the same purification system Similar size (30 tons). Inner geometry is different: cylindrical and taller but skinnier Access is still difficult (entry/exit flange is the same size). Perhaps possible to add second entrance point, but expensive Recirculation pump is outside the cryostat In LAPD, we obtained a purity too good to measure > 14ms with a TPC inside.

Idea set 1: Cryogenic questions Can we develop a cool down procedure that preserves the purity of the LAr used to fill the tank. (membrane cryostat needed? Large tank needed? If the 35ton phase 2 purity is also barely adequate (3 ms), can we unquestionably demonstrate the origin of the impurites? Can we eliminate the membrane cryostat as the source? Is this the only place to test new feedthrough designs? Is this a good place to test them? Are there new filtration materials that we want to test, for radon contamination for example? (Filtration system at PAB is shared and compromising it is frowned upon)

Idea set 2: What kinds of tests require the big inner space?? Light detection for tracks ~2-3 m distant Cold electronics attached to an APA? Air, LN2, LAr?? (cryostat is a faraday cage) Radon contamination studies?

Idea Set 3: another TPC? Unlikely that the current TPC will sit and gather dust after phase 2 is finished For example, move one APA and part of the DAQ to DAB for future DAQ development But time scale to start from scratch is ominous months?

Summary If you can do your test someplace else, you should! LAPD and 35ton have unique features – Large inner volumes – Large capacity filtration system with sophisticated diagnostics (gas analyzers and 5 purity monitors) – 35ton is a membrane cryostat