2016/08/05 (Friday)
| Setup: iZIP mode, DIB1/2/3 → cables → 3.2 MHz filters → DCRC55(1)/33(2)/50(3), Tower has been cooled below Al transition with mu-metal shield at standard position | |
| DCRC1 only powered overnight | |
| 0825 | Tower/MC/Coldplate = 231/230/425 mK, Still = 3.5 K / 550 μbar / 2 mW, G1/G2 = 885/815 mbar, 1K Pot = 3.15 K / 1.4 mbar, MB = 34.5% Boiloff rate seems to be on the fast side, despite a 10min/35min pressure release cycle yesterday. Maybe it's different for incomplete fills. |
| Looks like a 1K Pot failure overnight. Luckily circulation pressures seem to have stayed below 1 bar. At 5:42, 1K Pot pressure fell from 1.9 to 1.5 mbar, 1K Pot temperature began to rise, still and circulation pressures began to rise. Tower temperature began rising about 30 minutes later. | |
| 0830 | Open 1K Pot needle valve a few degrees more |
| 0835 | Tower 196 mK and falling, Still 85 μbar, G1/G2 = 450 mbar and falling quickly, 1K Pot = 1.60 K / 12 mbar and falling |
| 0840 | Fill LN2 cold trap bath |
| 0845 | Tower 112 mK and falling, Still 90 μbar, G1/G2 = 270 mbar and falling slowly, 1K Pot = 1.54 K / 6 mbar and settling |
| 0900 | Tower 54 mK and falling, Still 110 μbar, G1/G2 = 255/235 mbar and steady, 1K Pot = 1.60 K / 11 mbar and somewhat oscillatory |
| 1140 | Tower/MC/Coldplate = 37.0/34.5/155 mK, Still = 1.42 K / 80 μbar / 2 mW, G1/G2 = 215/200 mbar, 1K Pot = 1.42 K / 2.2 mbar |
| 1145 | Tweak 1K Pot needle valve open a little more |
| 1340 | Tower = 37.3 mK, Still = 80 μbar / 2 mW, G1/G2 = 215/200 mbar, 1K Pot = 1.43 K / 2.4 mbar |
| 1350 | Plug in and power up DCRC3. No noticeable change in base temperature |
| 1355 | Plug in and power up DCRC2. Tower spikes to 42 mK, then falls again. |
| 1410 | Tower = 38.5 mK, seems fairly stable. DIB2 qInner is still bad, trace seems to just wander around |
| 1411 | While turning FETs on and off on DIB2, Tower spikes to around 200 mK a couple of times. Cooling again. |
| 1430 | Had some doubts about the charge channel labeling, since DIB2 qInner is the bad one in terms of traces, but DIB2 qOuter seemed to be bad in the electrical checkout (qI Feedback→Gain/Source read open). The ODB agrees with the SQUIDtuningGUI, because we can see changes in traces when we change the corresponding offset. Tried to take some data to verify that qInner and qOuter as labeled by BatViewer agree (i.e. check which channel has the wandering trace). But some problems with data taking, need to get the DAQ back to its older settings. Later we got data working and took a short series of test data. BatViewer agrees that DIB2 qInner is the bad charge channel. |
| 1505 | Tower is holding pretty steady at 39.2 mK. 1K Pot = 1.41 K / 2.2 mbar - tweak 1K Pot needle valve open a little more |
| 1544 | Main bath = 20% |
| 1545 | Commence LHe transfer (18.4%) |
| 1650 | IVC = 5.4 nbar. On advice of Wolfgang and Vuk, open valve to pump on IVC with turbo pump continuously, even at base temperature. Maybe this will help prevent continued He buildup in IVC - otherwise I expect we will start encountering problems 4 days after the last warmup/pumpout (which was yesterday). |
| 1715 | Turbo pump pressure = 0.86 nbar (IVC pumping pressure) |
| 1720 | Fill LN2 cold trap bath |
| 1722 | End LHe transfer (91.4%) |
| 1725 | Turn off still heater, in case there's a 1K Pot failure probably better to have it off. |
| 1725 | MC = 38.6 mK. Still = 60 μbar. 1K Pot = 1.45 K / 3.6 mbar. Tweak 1K Pot needle valve open a few more degrees |
| 1727 | Release pressure from MB, 5 min after end of transfer |
| 1752 | Release pressure from MB, 30 min after end of transfer |
| Tweak 1K Pot needle valve. After about 5 minutes the 1K Pot has settled to 1.689 K/40 mbar. |