2021/02/18 (Thursday)
- Lab in-person: Matt
- Virtual partner: Zach, Derek
| Status | Run 74 cooldown. Initial LHe Transfer yesterday |
|---|---|
| 1150 | Matt enters lab. |
| 1150 | MB = 64.2% / 178 mbar+1atm |
| 1155 | MC(Cernox)/Sorb/1K Pot = 4.77/8.4/6.63 K. G1(fridge) = 556 mbar (3He pump off). |
| 1155 | Turbo on IVC = 4.6 nbar. With turbo valved out for 1 minute, IVC = 63 nbar. Open Turbo valve again, we'll keep pumping on IVC. |
| This is worse than last time, Oct 8. There were hints yesterday that helium leaked into the IVC late in the transfer. We'll see whether we can cool to 1K. | |
| 1305 | Pump out line leading to 1K Pot with scroll pump. Then switch over to 4He pump. Turn on 4He pump then change pump exhaust to recovery and open valve to recovery lines. |
| 1310 | Check pressure in 1K Pot (open 1K Pot speedivalve with V4a closed): Mechanical gauge = 0.35 bar. 1K Pot temperature dips to 4.8 K, then up to 5.3 K. Note: with V4a open and 4He Pump valve closed, the pressure reads lower, 0.27 bar. |
| 1315 | Pump out 1K Pot in steps, alternating between V4a and the 1K Pot speedivalve, keeping P2 below 10 mbar, opening V4a for short bursts when necessary. After 6 speedivalve iterations leave V4a and 1K Pot speedivalve open. 1K Pot → 3.4 K / 1.2 mbar. Sorb falls, MC unaffected. |
| 1320 | MC(H35)/Tower = 4.81/4.61 K. (Coldplate/Still = 2.537/2.693 kΩ = 17.7/6.1 K. These don't have good calibrations here.) |
| 1325 | MC(H35)/Sorb = 4.81/4.2 K. G1 (fridge) = 530 mbar and falling. |
| 1325 | Open 1K Pot needle valve → 10°. 1K Pot → 2.8 K / 12 mbar. Open 1K Pot needle valve → 20°. 1K Pot → 2.5 K / 20 mbar. MC(H35) → 3.3 K |
| looks good so far [image not archived: smile.svg] | |
| 1335 | Open 1K Pot needle valve → 30°. 1K Pot → 2.1 K / 36 mbar, oscillating. |
| 1335 | Fill LN2 cold trap bath |
| 1340 | 1K Pot = 1.8 K / 36 mbar. MC(H35)/Sorb = 2.93/4.0 K, G1 (fridge) = 268 mbar |
| 1400 | 1K Pot pressure has fallen to 13 mbar, bouncing a little. MC = 2.09 K, I guess it's now below the lambda point. Actually, last time at 2.07 K the Still pressure and temperature shot up. Getting close to that point now, maybe. |
| 1405 | MC(H35)/Tower = 2.06/2.05 K. Coldplate/Still = 3.38/3.42 kΩ =? 2.84/2.07 K. |
| 1410 | Open 1K Pot needle valve → 40°. MC = 2.05 K, seems kinda stuck at the lambda point, 1K Pot low… |
| 1413 | 1K Pot pressure shoots off-scale, then falls again, to around 60 mbar, bounces to 150 mbar, oscillating. |
| 1415 | 1K Pot = 1.73 K / 100 mbar, oscillating. MC(H35) = 2.05 K, G1 (fridge) = 57.0 mbar. |
| 1430 | MC finally falls a bit |
| 1430 | 1K Pot = 40° / 1.73 K / 100±20 mbar. |
| 1430 | MC(H35)/Tower = 1.99/1.96 K, G1 (fridge) = 56.2 mbar. |
| 1445 | Planning the DCRC setup. Found an ODB file from Run67 on 2018 Apr 1 (run28468.odb) and copied those settings, specifically trace lengths and LED settings. Plan is DCRC1/2+acc → DCRC50(3)/55(1) |
| Setup: DIB1/2+acc → SL 41/43 → 3.2 MHz filters → cables 2/3 → DCRC50(3)/55(1). | |
| 1455 | Power up the DCRCs. Note: later we'll try DCRC33(2) for HV biasing. For now it's just the two DCRCs. I have shorted the HV lead so that Side2 is grounded, so we can bias with the DCRCs themselves in the standard way. |
| 1505 | Try starting MIDAS. On the first try I couldn't get the programs to all start with both DCRCs enabled, but I got it going with only DCRC3 enabled, and the SQUIDtuningGUI.exe Pulse Viewer works, can see charge traces. |
| 1510 | After screwing around a bit got the DAQ programs started with both DCRCs enabled. Can see all four charge traces. |
| 1515 | Apply 6V bias to all 4 channels and mess a little with triggering. Seeing some pulses - good. |
| 1520 | 1K Pot = 40° / 1.73 K / 90±10 mbar. |
| 1520 | MC(H35)/Tower = 1.89/1.84 K, G1 (fridge) = 49.3 mbar. |
| 1540 | Matt exits lab |
| 1625 | 1K Pot = 40° / 1.73 K / 85±10 mbar. MC(H35) = 1.88 K, G1 (fridge) = 49.7 mbar. |
| 1630 | Close V3 and V9, leaving 32 mbar (G2) in the dump. Turn on 3He pump. |
| 1630 | Start circulation through Trap 2. V6 → 11.6%. Condenser peaks at 158 mbar. (G2 peaks higher than G1.) MC falls to 1.58 K. 1K Pot spikes then settles. |
| 1635 | V6 → 12.0%. Condenser peaks at 123 mbar. |
| 1640 | V6 → 12.4%. 1K Pot spike. Condenser peaks at 157 mbar. P1 (Still) falls, → 30 mbar. MC → 1.35 K |
| 1645 | V6 → 12.6%. Condenser peaks at 116 mbar. Still → 5.5 mbar. MC → 1.14 K |
| 1650 | V6 → 12.8%. Condenser rises relatively slowly, peaks at 139 mbar. Still → 5.5 mbar. MC → 1.16 K. It rose a bit but is now falling again (maybe going through Al s/c transition, should be mild compared to when we are using an external Al electrode) |
| 1655 | MC goes up and down a couple times, 1.14-1.18 K |
| 1700 | V6 → 13.0%. Condenser rises slowly, peaks at 128 mbar. Still → 4.0 mbar. MC sinking, → 0.72 K |
| 1705 | V6 → 13.4%. Condenser peaks at 131 mbar. Still → 2.8 mbar. MC → 0.59 K |
| 1710 | V6 → 13.8%. Condenser peaks at 131 mbar. Still → 1.6 mbar. MC → 0.35 K |
| 1715 | V6 → 14.2%. Condenser doesn't rise. Still → 0.95 mbar. MC → 0.26 K |
| 1720 | V6 → 15.0%. Condenser → 115 mbar. Still → 0.55 mbar. MC → 0.21 K |
| 1730 | V6 → 100%. Condenser peaks at 101 mbar. Still → 0.20 mbar. MC → 0.11 K, dropping faster |
| 1745 | MC(H35) = 41 mK, Still = 0.140 mbar, G1/G2 = 79/74 mbar. |
| 1750 | Open V14 to let the remaining mix out of the dump and into circulation. P1(Still) peaks at 70 mbar then falls again. MC(H35) peaks at 85 mK. Condenser peaks at 110 mbar. |
| 1815 | MC(H35) = 34.9 mK, Still = 0.800 mbar, G1/G2 = 77/71 mbar. |
| 1815 | Close V14 |
| 2030 | MC(H35) = 31.6 mK, Still = 0.140 mbar, G1/G2 = 77/72 mbar. |