2022/12/02 (Friday)
- 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 W side of fridge. NaI array undergoing scan, trigger threshold varies. |
| Warmed up yesterday for twenty-ninth 5K pumpout. Turbopumping IVC overnight | |
| 0955 | MB = 3.2% |
| 1100 | MC = 5.7 K |
| 1102 | Begin LHe transfer @ MB = 1.9% |
| 1110 | Turbo on IVC = 0.74 nbar. With Turbo valved out for 1 minute IVC = 6.3 nbar |
| 1110 | Close IVC valves at top of fridge. |
| 1115 | Fill LN2 cold trap dewar |
| 1115 | MB = 27.0% |
| 1115 | Turn on 4He pump. Open Recovery valve to 4He pump. Pump out line to 1K pot (speedivalve closed). Check pressure in 1K Pot (with V4a open, 4He pump inlet valve closed). 1K Pot = 0.33 bar on mechanical gauge. |
| 1120 | Pump out 1K Pot slowly, throttling the flow at the valve at the pump inlet, opening just until the pump gets louder, then waiting, then opening a little more, etc. With pump just a little loud, can see pressure go down at the mechanical gauge. When this is low, open valve a bit more. When P2 gets below 30 mbar open valve all the way. |
| 1125 | 4He pump valve open all the way. |
| 1125 | 1K Pot = 3.11 K / 3.2 mbar. G1 (fridge+dump) = 407 mbar. MC = 5.61 K. |
| 1135 | Open 1K Pot needle valve → 15°. 1K Pot → 2.85 K / 6.0 mbar |
| MC drops to 3.2 K | |
| 1140 | Open 1K Pot needle valve → 30°. 1K Pot → 2.59 K / 8.5 mbar |
| 1150 | Open 1K Pot needle valve → 45°. 1K Pot → 2.58 K / 8.5 mbar |
| 1200 | End LHe transfer @ MB = 95.8% |
| 1305 | MC/Still/1KPot = 2.08/1.77/1.51 K. G1(fridge+dump) = 52 mbar, flattening. |
| 1335 | MC/Still/1KPot = 1.78/1.82/1.51 K. G1(fridge+dump) = 40 mbar, flattening. |
| 1410 | MC/Still/1KPot = 1.67/1.72/1.55 K. G1(fridge+dump) = 31 mbar, pretty flat. |
| 1410 | Close V3 and V9, leaving 49 mbar mixture in dump (G2) |
| 1410 | Turn on 3He pump. G1(condenser) → 38 mbar |
| 1410 | Start circulation through Trap 1. V6 → 12.6%. Condenser peaks at 170 mbar. MC(H35) → 1.42 K. Still → 1.47 K / 45 mbar |
| 1420 | V6 → 13.0%. Condenser(G1) peaks at 206 mbar. MC(H35) → 1.39 K. Still(P1) → 1.44 K / 40 mbar. |
| 1440 | V6 → 13.4%. Condenser(G1) peaks at 263 mbar. MC(H35) → 0.97 K. Still(P1) → 1.14 K / 3.8 mbar. |
| 1455 | V6 → 13.8%. Condenser(G1) peaks at 173 mbar (and kinda plateaus). MC(H35) → 0.67 K. Still(P1) → 1.14 K / 2.4 mbar. |
| 1505 | V6 → 14.4%. Condenser(G1) peaks at 187 mbar. MC(H35) → 0.25 K. Still(P1) → 1.14 K / 0.75 mbar. |
| 1530 | V6 → 15.0%. Condenser(G1) peaks at 190 mbar. MC(H35) → 0.19 K. Still(P1) → 1.13 K / 0.45 mbar. |
| 1535 | V6 → 100.%. Condenser(G1) peaks at 199 mbar. MC(H35) → 72. mK. Still(P1) → 1.08 K / 0.13 mbar. |
| 1550 | Open V14 to pull the rest of the mixture out of the dump into circulation. Still peaks at 22 mbar, Condenser peaks at 230 mbar, MC peaks at 69 mK, then all relax again. 1KPot = 1.55 K / 9.0±0.5 mbar. |
| 1610 | Still = 0.45 mbar. Close V14 |
| 1610 | MC = 32.2 mK |
| 1615 | Plug in DCRCs 1&3 |
| 1620 | Turn on DAQ programs. Some channels already have baselines around -0.7 V. Others went there after relocking. DCRC1pD and DCRC3pD are still off after relocking. |
| 1750 | Adjust phonon offsets to get all baselines near -0.80 V |
| 1750 | MC = 30.3 mK |
| 2235 | Readjust offsets to get all phonon baselines near -0.800 V. Looks like detector cooled a little more. |
| Odd variations occurring in MC temperature and fridge pressures. Over three hours the MC temperature has gone up and down four times in a somewhat irregular pattern between 29 and 31 mK. At the same time the condenser pressure has gone up and down between 180 and 210 mbar, and the still pressure has varied between 0.09 and 0.12 mbar. |