| Teleconference link: | https://fnal.zoom.us/j/9082275310 |
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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
- This cooldown: no IVC leak, fridge working fine. Base is 34 mK. All channels working.
- Had a DAQ glitch a week ago that was applying incorrect detector biases - fixed that.
- Performing hot LED flashes to restore phonon collection efficiency after running the motor - seems to work.
- Studying stepper motor behavior indicates that it probably isn't really working right…
- Heating during stepping - tried smoothing capacitors and changing dwell
- DC testing shows resistance increase of ~10 Ohm @detector which can explain heating.
- Solder joint to NbTi may cause local (runaway) heating to drive ~7 cm of NbTi normal
- Conclusion: may only be moving <4 steps each time we move for a total of <1mm so far.
- Will try to make a bunch of little moves and search for evidence of Am movement in phonon signals.
- Probably will end the run within one week.
- 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
- NEXUS setup
- 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. | Teleconference link: | https://fnal.zoom.us/j/9082275310 |
