2019/04/16 (Tuesday)
| Status | Room temperature. All mixture in dump. LN2 traps warm. 1K Pot needle valve open. 1 atm nitrogen exchange gas in IVC. Cryostat vacuum jacket pumped out. |
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| 1200 | Start disassembling lead stack behind fridge (west side) |
| 1320 | Perform 300 K electrical checkout: |
300 K Electrical Checkout results:
- Problems now that did not exist during the 300K checkout at the beginning of the run:
- DIB1pD SQUID and Feedback are open (we saw this at base)
- DIB3pB Feedback reads low, 1.1 kΩ, s/b 20 kΩ (didn't notice this till now)
- DIB4pA SQUID open, Feedback high at 17 MΩ, s/b 20 kΩ (we saw this at base)
- Problems that we had since before the run
- DIB3pA SQUID open, DIB3pB SQUID too high, 550 kΩ s/b 4 kΩ
We also know that DIB3pC is inoperable and suspect the input coil is bad.
In terms of the next run:
- will presumably need to swap out DIB3 SQUET.
- could keep the others because the bad channels are not readout channels. BUT…
- Nick says a SQUID on DIB4 had pretty bad behavior, so he suggests swapping out that SQUET too.
| 1335 | Close 1K Pot needle valve |
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Working on 4He Pump rebuild.