2022/08/25 (Thursday)
- 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. |
| Warmed to > 5K yesterday and pumped helium out of IVC overnight. DCRC1&3 off. Heaters off. | |
| 1005 | MB = 44.2% |
| 1030 | MC/1KPot/Sorb = 5.8/6.8/8.7 K. G1(fridge+dump) = 546 mbar. |
| 1035 | Turbo on IVC = 1.4 nbar. With Turbo valved out for 1 minute, IVC = 12 nbar. |
| 1040 | Close valves to IVC at top of fridge stand. |
| 1045 | Pump out lines up to 1K Pot speedivalve with 4He pump. Close valve at pump then check pressure in IVC: 0.23 bar on mechanical gauge. Pump out 1K Pot in steps by opening speedivalve and V4a successively, opening V4a in brief spurts, keeping pressure on pump below 10 mbar. After about five cycles leave speedivalve and V4a open. |
| 1050 | 1K Pot → 3.4 K / 2.4 mbar. Fridge pressure falling. MC temperature falling slowly. |
| 1055 | Open 1K Pot needle valve → 15°. 1K Pot →3.05 K / 7 mbar |
| 1100 | Increase 1K Pot needle valve → 30°. 1K Pot →2.88 K / 11 mbar |
| 1100 | MC drops quickly, 5.6→3.5 K. Sorb drops to 4.0 K, I think that's minimum. |
| 1210 | MC = 2.2 K, 1K Pot = 1.52 K / 5.5 mbar, G1(fridge+dump) = 61 mbar. |
| 1210 | Increase 1K Pot needle valve → 45°. 1K Pot →1.54 K / 6.5 mbar |
| 1215 | Increase 1K Pot needle valve → 60°. 1K Pot →1.56 K / 8.5 mbar |
| somewhat concerning that 1K Pot pressure so low. Maybe it will snap out of it. Currently MC seems kinda stuck around 2.08 K, could be the superfluid lambda point, maybe there will be a big spike soon… | |
| 1230 | 1K Pot pressure jumps up and oscillates, good. 1K Pot → 1.64 K / 24 mbar. MC = 2.07 K, cooling very slowly |
| 1245 | Sudden drop in MC, 2.06→1.98 K, looks like it got through the lambda point |
| 1410 | MC = 1.86 K, 1K Pot = 1.64 K / 24 mbar, G1(fridge+dump) = 41 mbar. |
| 1410 | Start 3He pump |
| 1440 | G1/G2 have settled at 41/33 mbar. Close V3 to prepare for circulation. |
| 1440 | Start circulation through Trap 1. V6 → 12.6%. Condenser peaks at 246 mbar. MC(H35) → 1.6 K. Still → 1.65 K. |
| 1445 | V6 → 13.0%. Condenser(G1) peaks at 325 mbar. MC(H35) → 1.47 K. Still(P1) → 1.52 K / 70 mbar. |
| Still pressure wiggling. MC rises a bit, 1.46→1.50 K | |
| 1455 | V6 → 13.4%. Condenser(G1) peaks at 396 mbar. MC(H35) → 1.28 K. Still(P1) → 10 mbar. |
| 1540 | While I was out of the lab Condenser peaked and fell again, also MC temperature between about 1.15 and 1.40 K. |
| 1540 | V6 → 13.8%. Condenser(G1) peaks at 258 mbar. MC(H35) drops suddenly from 1.25 to 1.14 K then rises slowly, if did that a half hour ago too, looks like it's trying to power through the Al transition. Still(P1) → 1.20 K / 3.4 mbar. |
| 1550 | V6 → 14.4%. Condenser(G1) peaks at 267 mbar. MC(H35) → 0.70 K. Still(P1) → 1.17 K / 1.9 mbar. |
| 1600 | V6 → 15.0%. Condenser(G1) peaks at 266 mbar. MC(H35) → 0.39 K. Still(P1) → 1.16 K / 1.1 mbar. |
| 1610 | V6 → 100%. Condenser(G1) peaks at 258 mbar. MC(H35) → 0.14 K. Still(P1) → 1.12 K / 0.4 mbar. |
| 1622 | Begin LHe transfer @ MB = 35.8% |
| 1630 | Oops - just noticed V14 was open the whole time during the cooldown. Close it now. Still falls from 0.28 → 0.10 mbar. |
| 1645 | MC/Coldplate = 31.5/147 mK, Still = 1.11 K / 0.080 mbar, 1K Pot = 1.62 K / 24±2 mbar |
| I set up the heat gun to blow on the stripline elbow at the top of the fridge during transfer. (The theory is that when this gets cold the o-ring leaks helium into the IVC.) Had to do it at a bit of a distance to keep from getting too hot. Checking occasionally to make sure it's not too hot. | |
| 1705 | End LHe transfer @ MB = 92.9% |
| 1720 | MC/Coldplate = 27.8/145 mK, Still = 1.11 K / 0.080 mbar, 1K Pot = 1.61 K / 22±2 mbar |
| 1720 | Plug in DCRCs 1&3 and turn on DAQ programs |
| 1735 | Set all phonon channels high in their transitions, with QET biases between 180-225 uA. Seeing good pulses. |
| 1755 | IbIs on DCRC1pA. dP/dI = 1.0 uV @ QET bias = 183.0 uA |
| 1805 | IbIs on DCRC1pB. dP/dI = 1.0 uV @ QET bias = 182.1 uA |