2022/08/24 (Wednesday)
- Lab in-personnel: Matt
| Status | Run 76 in progress |
|---|---|
| Setup | Cables 2/3/1 → diverter/nothing/nothing → Side2-readout HV CONN 1/3/2 → HV 1(L)/2(R) → DCRC50(3)/DCRC55(1), DCRC33(2)→HV control, NaI trigger signal → DCRCX(4) Lead/poly shield fully assembled. Boron-filled socks covering NaI detectors. PuBe behind lead wall on West side of lead/poly shield. |
| Restarted circulation recently after warming to 5K and pumping out IVC. | |
| First data series after the 5K warmup/pumpout looked much better. But the next day (yesterday) all channels looked stuck in normal, couldn't get any pulses. | |
| 1030 | Currently MC base is around 35 mK with constant spikes, most pretty small but some up to 100 mK |
| 1045 | Try mini-IbIs on DCRC3pA, seems to be stuck in superconducting state. Contrast to most channels yesterday stuck in normal state. Didn't try this one yesterday though. (This is Side2pB.) |
| 1050 | Try mini-IbIs on DCRC3pB, also seems to be stuck in superconducting state. (This is Side2pA.) |
| 1105 | Try mini-IbIs on DCRC1pD - found transition (and kinda ugly noise). dP/dI = 1 uV @ QET bias 286.6 uA, very high. (This is Side2pE.) |
| 1120 | Mini-IbIs on DCRC1pB - found transition. dP/dI = 1 uV @ QET bias 229.9 uA, about as high as before the 5K pumpout. (This is Side2pF.) |
| 1135 | Mini-IbIs on DCRC1pA - found transition. dP/dI = 1 uV @ QET bias 228.9 uA, high. (This is Side2pC.) |
| 1150 | Mini-IbIs on DCRC3pD - found transition. dP/dI = 1 uV @ QET bias 265.4 uA, high. Strong 10kHz oscillations. (This is Side2pE.) |
| 1200 | Check DCRC3pA&B again, outer-ring channels still seem stuck in superconducting. |
| OK, not worth trying to take data in this state. | |
| 1205 | Turn off DAQ programs, power down DCRCs 1&3 |
| Early in the run we weren't pumping on the IVC and it worked a long time. After the recent 5K pumpout I continuously pumped the IVC after cooling to base, and things went bad quickly. Maybe try again but don't pump? | |
| 1205 | Close V6 to stop circulation |
| 1210 | Turbo on IVC = 1.4 nbar. Close valve at Turbo to monitor IVC pressure. |
| 1210 | Close 1K Pot needle valve |
| 1250 | G1 (condenser) has fallen to 21 mbar, P1 (still) has risen to 38 mbar, 1K Pot = 1.38 K / 2.0 mbar, MC has risen to 0.57 K. IVC = 19 nbar. |
| 1255 | Close 1K Pot speedivalve, V4a, 4He pump valve, switch 4He pump outlet to exhaust and close 4He pump recovery valve. Turn off 4He pump and 3He pump. |
| 1300 | Turn on MC Heater and Still Heater each to 20 mW |
| 1300 | IVC → 120 nbar. MC/1KPot → 2.0/2.2 K |
| 1305 | IVC falls again to 34 nbar. Maybe recondensing onto some other cold spot? |
| 1305 | Still is off-scale. Open V3 to connect Condenser and Still sides. Condenser rises from 35→75 mbar. |
| 1310 | Fill LN2 cold trap bath |
| 1320 | MC/1KPot = 3.4/3.2 K and rising. G1(fridge) = 430 mbar and rising. IVC = 54 nbar. |
| 1345 | MC/1KPot = 3.9/4.1 K. G1(fridge) = 800 mbar. IVC = 100 nbar. |
| 1405 | MC/1KPot = 4.1/4.3 K, flattening. G1(fridge) = 909 mbar. IVC = 140 nbar. |
| 1405 | Open V14 to release fridge pressure to dump. Cooling effect on MC and 1K Pot, also dip in IVC pressure. MC bounces back to higher temperature. |
| 1425 | MC/1KPot = 4.9/4.3 K, flat. G1(fridge+dump) = 535 mbar. IVC = 220 nbar. |
| 1500 | MC/1KPot = 5.0/4.3 K, flat. G1(fridge+dump) = 540 mbar. IVC = 250 nbar. |
| 1505 | Noticed a few loose KF flange clamps on top of fridge in connections between stripline elbow, E-box, pumping lines. Tighten these. |
| 1630 | MC/1KPot = 5.0/5.1 K, flat. G1(fridge+dump) = 540 mbar. IVC = 250 nbar. |
| 1700 | MC/1KPot = 5.0/5.1 K, flat. G1(fridge+dump) = 540 mbar. IVC = 250 nbar. |
| 1700 | Start pumping IVC with Turbo. Turbo → 14 nbar. MC and 1K Pot start getting warmer. Apparently the 0.25 ubar of He was thermally locking them to the 4K bath. |
| 1705 | MB = 65.9% |
| 1710 | MC/1KPot/Sorb = 5.17/5.36/6.7 K, rising. G1(fridge+dump) = 541 mbar. Turbo on IVC = 8.6 nbar. |
| 2045 | MC/Sorb = 9.7/10.1 K Turn off MC and Still heaters |