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Agenda

Run 71 status
- New movable source design with no potentiometer, end-contact sensors instead at -13.10 mm and +41.67 mm
- At 77K discovered another leak into IVC. Warmed up and opened IVC, saw some scratches on upper IVC flange surface, buffed them out with Scotch Brite
- resealed, cooling to 77K again today
Should we design and build new cold hardware?
- Soudan towers didn’t perform thermally as well as they should have (graphite tubes too conductive)
- Soudan towers had requirements we can relax
  - FET heat not a consideration for phonon-only devices
  - Materials don’t need to be as radiopure
- Soudan tower concept
  - Design description from Walter Ogburn’s thesis
- NEXUS setup
  - More detailed CAD
  - NbTi cable thermal conductance: G=3.11e-8*T^1.19 W/mK (for 1m, 40 wires, base = 100 mK)
  - Tekdata NbTi, MDM-25 quote: ~$715 each
  - Cheap ($10/inch^2) SC flex PCB inside MC can Photo
SQUET recall
- Martin wants 5 of our 9 SQUETs sent back to Colorado. He wants good SQUIDs.
- A lot of issues to deal with:
  - there are bad SQUID chips
  - we need to change shunt resistances for iZIPv6 versus HV, but don't want to wirebond too many times
  - some SQUETs have problems at the pins
    - can we get spare SQUETs with the SQUID chips removed? Could theoretically glue good SQUID chips onto good SQUET.
- Anthony says we may be able to get alternative SQUID chips
- We have 1.5-ish months to deal with this
Analysis status:
- Run 68 (n,gamma with S101)
  - Migdal analysis pending
  - New (n,γ) simulations, modified signal shape
- Run 70
  - analysis team includes Pramod, Matt, maybe Zach - should coordinate, have meetings
  - Need to look at the recent PuBe data, work on a low-threshold energy quantity, see if we can see a hint of (n,γ) signal. Also develop cuts and look for low-energy junk
- Run 67 (USD detector with novel time-dependent gain)
  - Dongming has characterized lots of microscopic processes, wants us to write a paper
  - Matt will work on rough model of detector behavior
- SiHV event reconstruction
  - Derek working on this
  - Hongguang developing connection to DMC
Lab and infrastructure
- Leak detector: After pump rebuild, pump no longer turned. Jake and Derek fixed this problem. However, it still doesn't seem to be able to pull a good vacuum. Using scroll pump assist in order to use leak detector.
- Transferring old raw data from /cdms1 to Google shared drive. Have moved 4.6 TB so far.
- PuBe source: plan is to take over the source on our permit, house it in PAN443b, the right cleanroom. We've been storing it in the steel box there with lead, now we will use the “howitzer”.
- Sten returned DCRC55(1) a while ago. We're currently using it. We should ask him again some time if he can diagnose some of the DCRC glitches.
Possible heat-sinking changes for HV (phonon-only) runs:
- Disconnect 4K heatsinking and connect 4K and Still stages
  - to reduce temperature at tower pins, reducing noise contribution there
  - would make Still warmer but this may not be a bad thing
- Disconnect 600mK rod and connect Still and Coldplate stages
  - to reduce SQUID-card temperature. Could probably get wirebonds to superconduct
  - may have an impact on base temperature. May need to heat the Still which would exacerbate this
Future 150mm runs
- 150mm w/phonons - need to design 600mK rod to accommodate 150mm cans
- Received 4/3-inch DIBs from TAMU - now we can house either detector for phonon readout (would need to machine faces on 4/3-inch housing for DIBs)
- S1501 and S1502 sent back to TAMU
- We have decided we can run 8 phonon channels
  - Preferred DIB-pad layout: two DIBs separated by 120 degrees
  - Himangshu's mask design: PDF download
  - Will use existing vacuum-interface electrode, mounted on side opposite the phonon side
  - Will connect directly to two DCRCs, with one diverter board to route one tower wire to HV connection
  - We'll want LEDs - are there some mounted on the DIBs? We can mount external LEDs too - existing electrode has mounts.
- First 150mm phonon detector will be monolithic, but “donut+hole” arrangement (active veto) proposed as well.
- Aiming for May to finish fabrication and start run.
Other future runs
- Future HVeV runs?
  - Berkeley can help us with a Soudan-style housing mount (3“ or 4”?)
  - then use original tower, can try different heatsinking for colder SQUID card
  - would need to install optical fiber
    - through top or through stripline tube?