2018/03/05 (Monday)
| Status: LN2 cap-off transfer yesterday. Waiting for LHe - there will be some today. | |
| 0930 | MC(Cernox) = 76.9 K, Sorb = 118.2 K, IVC = 2.2 mbar, G1 (fridge) = 605 mbar |
| 0930 | Pump out IVC |
| 0935 | Fill LN2 cold trap bath |
| 0950 | Start pumping on IVC with Leak Detector. Background = 2700 pbarL/s. |
| 0955 | Begin blowing out LN2 into bomb Dewar. G3 (main bath) = 454 mbar. |
| 0955 | Check the short from DIB2qI FET gate to chassis. Qi_feedback-chassis = 10 nS. Chassis-qI_drain or source = 25 nS. These are a little worse than yesterday (7.5/15 yesterday). So leak is around 40 MOHm. |
| 1035 | G3 falling, to around 185 mbar, probably almost finished removing LN2 |
| 1035 | LD signal rose as soon as the LN2 was all removed, when G3 fell. LD → 140,000 pbarL/s = 1.4e-4 mbarL/s. Maybe this is just from He gas at top of fridge. |
| 1045 | Stop pressurizing main bath, LN2 blowout finished. |
| 1055 | Pump on main bath with scroll pump. |
| LD signal starts falling when we start pumping on main bath. This could be a concern - could be that the bottom IVC seal has a leak now that it's cold. | |
| 1100 | LD = 4500 pbarL/s = 4.5e-6mbarL/s and continues to fall |
| 1101 | P2 < 1 mbar. close V1A, V4A. Isolate the scroll pump. |
| 1105 | LD = 1200 pbarL/s |
| 1105 | Fill main bath with He gas to 474 mbar above 1atm on G3. LD signal begins to rise. LD > 100,000 pbarL/s. Also let some He into 1K Pot through its speedivalve. |
| 1100 | LD = 200,000 pbarL/s = 2e-4 mbarL/s and flat. This is a pretty bad leak. Not sure whether this will be a problem when cold. |
| 1115 | Turbo pump = 25 nbar pumping on IVC. Stop pumping, Let 63 μbar He exchange gas into IVC. |
| 1135 | Pump out 1K Pot with scroll pump. I know I pressurized it earlier, but lately we've been leaving it at vacuum during the LHe fill, and that seems to work well. Harder to start it I think when it's full of He. |
| 1140 | MC(Cernox) = 77.0 K, Sorb = 125.9 K, IVC = 74 μbar, G1(fridge) = 598 mbar. |
| 1145 | Begin initial LHe transfer |
| we'll monitor changes in the crystal resistance as we cool to 4K by measuring through a qBias line to the Side 2 electrode (measuring through the 40 MOhm bias resistor). | |
| 1155 | MC(Cernox) = 77.0 K, Sorb = 127.7 K, IVC = 74 μbar, G1(fridge) = 597 mbar. DIB1 qIbias-QET D = 25.5 nS |
| 1205 | MC(Cernox) = 76.9 K, Sorb = 126.8 K, IVC = 54 μbar, G1(fridge) = 596 mbar. DIB1 qIbias-QET D = 25.4 nS |
| 1220 | MC(Cernox) = 74.6 K, Sorb = 106.0 K, IVC = 12 μbar, G1(fridge) = 578 mbar. DIB1 qIbias-QET D = 25.4 nS |
| 1235 | MC(Cernox) = 63.0 K, Sorb = 59.9 K, IVC = 19 μbar, G1(fridge) = 531 mbar. DIB1 qIbias-QET D = 25.4 nS |
| 1245 | 1K Pot = 7.0 K |
| 1252 | MC(Cernox) = 49.5 K, Sorb = 8.1 K, IVC = 25 μbar, G1(fridge) = 472 mbar. DIB1 qIbias-QET D = 25.4 nS |
| 1305 | MC(Cernox) = 40.5 K, Sorb = 7.6 K, IVC = 30 μbar, G1(fridge) = 480 mbar. DIB1 qIbias-QET D = 25.4 nS |
| note IVC pressure is rising a little, I guess that's from the cold leak. | |
| 1320 | MC(Cernox) = 29.2 K, Sorb = 6.6 K, IVC = 34 μbar, G1(fridge) = 462 mbar. DIB1 qIbias-QET D = 25.4 nS |
| 1335 | MC(Cernox) = 17.4 K, Sorb = 6.0 K, 1K Pot = 4.76 K, IVC = 34 μbar, G1(fridge) = 457 mbar, Main bath = 51.9%. DIB1 qIbias-QET D = 25.3 nS |
| 1340 | MC hits 10 K, start pumping out IVC with turbo pump |
| 1340 | MC(Cernox) = 10.1 K, Sorb = 5.6 K, 1K Pot = 4.43 K, G1(fridge) = 450 mbar, Main bath = 58.2%. DIB1 qIbias-QET D = 24.8 nS |
| 1342 | Crystal conductance drops fast: MC(Cernox) = 4.8 K, DIB1 qIbias-QET D = 4 nS |
| 1344 | … MC(Cernox) = 4.3 K, DIB1 qIbias-QET D = 1.23 nS |
| 1345 | MC(H35) = 4.29 K, Sorb = 5.4 K, 1K Pot = 4.32 K, G1(fridge) = 445 mbar, Main bath = 63.1%. DIB1 qIbias-QET D = 1.07 nS |
| 1347 | DIB1 qIbias-qObias = 9.38 nS (was 13 nS) |
| 1350 | Tower = 4.27 K, Sorb = 5.4 K, 1K Pot = 4.33 K, G1(fridge) = 444 mbar, Main bath = 69.6%. DIB1 qIbias-QET D = 1.04 nS |
| 1400 | Tower = 4.29 K, Sorb = 5.4 K, 1K Pot = 4.32 K, G1(fridge) = 452 mbar, Main bath = 65.7%. DIB1 qIbias-QET D = 1.17 nS |
| bath level went down, probably because transfer stick not pushed down far enough in Dewar. Push down transfer stick. | |
| 1410 | Tower = 4.29 K, Sorb = 5.5 K, 1K Pot = 4.31 K, G1(fridge) = 440 mbar, Main bath = 76.3%. DIB1 qIbias-QET D = 1.04 nS |
| 1420 | Tower = 4.30 K, Sorb = 5.4 K, 1K Pot = 4.24 K, G1(fridge) = 454 mbar, Main bath = 76.1%. |
| 1425 | Tower = 4.30 K, Sorb = 5.4 K, 1K Pot = 4.24 K, G1(fridge) = 459 mbar, Main bath = 71.3%. |
| 1430 | End LHe transfer @ Main Bath = 66.2% |
| 1445 | Check the short from DIB2qI FET gate to chassis. Qi_feedback-chassis = 4-6 nS, kinda unstable. Chassis-qI_drain or source = 21 nS. Slightly better than this morning. Leak is around 45 MOHm. |
| 1450 | Plug DIB1/2 into DCRC50(3)/DCRC55(1). Start MIDAS. Adjust some ODB settings. |
| 1515 | See some pulses. Tried to zoom in to 0.8 ms window - then for some reason the trigger threshold settings were acting weird, had to set them very high, previously they were behaving OK. |
| 1520 | Restart MIDAS programs. Now triggering seems to work. With 5V bias (from DCRC, all 4 channels) see pulses on DIB1qO with trigger threshold = 80 See pulses on the 3 other channels too at trigger time while triggering on DIB1qO. So we see crosstalk and verify that timing link works. |
| 1530 | Try bias of 10 V. See decent pulses in all channels. Trigger thresholds of 100 seem ok for all channels except DIB1qI, which needs a higher threshold, maybe 400. |
| 1540 | Try turning on the LEDs. No noticeable change in temperature. But looking at the charge channels it's clear that LED pulses are occurring. We'll let it bake overnight. |
| 1550 | Fill LN2 cold trap bath |
| 1555 | Set charge biases to 0 V (almost forgot) |