2020/03/01 (Sunday)
| Setup | Run 72. DIB 1/3/4 → Stripline 43/41/48 → Cable 3/2/1 → nothing/nothing/accessory_interposer → HV_Conn 1/3/2 → HV 1/2 → DCRCX(4)/DCRC55(1). DCRCs on overnight. No shield. |
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| Yesterday the LakeShore was giving incorrect readings until the range was adjusted and returned. Just after that, the Tower temperature was reading a few mK higher than before, and settled, but didn't quite return to the earlier base. Did something actually heat the fridge or is this something to do with the thermometers/LakeShore bridge? Another thing that was different yesterday was that the Still pressure has dropped significantly - it had been higher than average during this run, 0.2 mbar instead of 0.1 or less, and now it's down to 0.11 or 0.12. Still temperature is lower too. Circulation pressures seem to be a little higher than a couple days ago. Coldplate is cooler. It could be that the colder still is resulting in a somewhat warmer base temperature. | |
| 1205 | Tower/MC/Coldplate = 54.6/37.1/186 mK, Still = 1.37 K / 0.120 mbar / 0 mW, G1/G2= 397/378 mbar, 1K Pot = 2.09 K / 24 mbar. MB = 30.0% |
| 1210 | Open 1K Pot needle valve wider, 30°→40°. Minor change, 1K Pot → 2.12K/30 mbar, Still pressure unchanged, Circulation pressures up slightly. Tower unaffected. |
| 1220 | Fill LN2 cold trap bath |
| 1234 | Begin LHe transfer @ MB = 29.6% |
| 1250 | Tower temperature spiked at beginning of transfer, as normal. But now it's climbing steadily. Why? Tower = 61.6 mK |
| 1250 | Check phonon channels to see if there is heating due to something in a bad state. They all look OK. |
| 1306 | End LHe transfer @ MB = 90.9% |
| 1315 | Tower temperature peaked at 67.5 mK, now dropping after transfer |
| 1335 | Tower = 59.7 mK and dropping seems to be falling back close to the pre-transfer base |