2022/11/17 (Thursday)
- Lab in-personnel: Matt, Zach
| 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 trigger window = 4.73 - 5.13 MeV |
| Warmed up yesterday for twenty-fourth 5K pumpout. Turbopumping IVC overnight | |
| 1125 | MB = 0.5% |
| 1206 | Begin LHe transfer @ MB = -0.1% |
| 1215 | Turbo on IVC = 0.86 nbar. With Turbo valved out for 1 minute IVC = 8.6 nbar. |
| 1215 | Close IVC valves at top of fridge. |
| 1215 | MC = 9.72 K. Like last time the MC didn't cool off much after turning off the heaters - in earlier cycles it fell much further overnight, to around 6 K or something. Combine this observation with the fact that the pressure in the IVC after we warm up has been lower than previous cycles. Does this mean the IVC is being pumped out more thoroughly? Maybe some trapped He has finally been removed? Unfortunately this is not improving our hold time, it's getting worse. |
| 1220 | Fill LN2 cold trap bath |
| 1220 | MB = 22.1% |
| 1220 | 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. |
| 1220 | 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. |
| 1225 | 4He pump valve open all the way. |
| 1225 | 1K Pot = 3.42 K / 3.4 mbar. G1 (fridge+dump)=465 mbar. MC = 9.71 K. |
| 1301 | End LHe transfer @ MB = 95.0% |
| 1325 | 1K Pot = 2.98 K / 3.4 mbar. G1 (fridge+dump)=395 mbar. MC = 3.30 K. |
| 1335 | 1K Pot = 2.78 K / 3.4 mbar. G1 (fridge+dump)=355 mbar. MC = 3.21 K. |
| 1335 | Open 1K Pot needle valve → 15°. 1K Pot → 2.48 K / 5.5 mbar |
| 1345 | Open 1K Pot needle valve → 30°. 1K Pot → 2.33 K / 7.0 mbar |
| 1350 | Open 1K Pot needle valve → 45°. 1K Pot → 2.18 K / 9.3±0.3 mbar |
| 1355 | MC = 2.91 K. G1(fridge+dump) = 237 mbar. |
| 1454 | MC/Still/1KPot = 2.06/1.88/1.52. G1(fridge+dump) = 47 mbar and somewhat flat. |
| 1455 | Close V3 and V9, leaving 44 mbar mixture in dump (G2) |
| 1457 | Turn on 3He pump. G1(condenser) → 60 mbar |
| 1502 | Start circulation through Trap 1. V6 → 12.6%. Condenser peaks at 324 mbar. MC(H35) → 1.52 K. Still → 1.54 K / 45 mbar |
| 1512 | V6 → 13.0%. Condenser(G1) peaks at 201 mbar. MC(H35) → 1.22 K. Still(P1) → 1.26 K / 6.0 mbar. |
| 1517 | V6 → 13.4%. Condenser(G1) peaks at 205 mbar. MC(H35) → 1.13 K. Still(P1) → 1.13 K / 3.6 mbar. |
| 1522 | V6 → 13.8%. Condenser(G1) peaks at 198 mbar. MC(H35) → 1.05 K. Still(P1) → 1.09 K / 2.0 mbar. |
| 1530 | V6 → 14.4%. Condenser(G1) peaks at 192 mbar. MC(H35) → 0.64 K. Still(P1) → 1.09 K / 1.0 mbar. |
| 1540 | V6 → 15.0%. Condenser(G1) peaks at 177 mbar. MC(H35) → 0.25 K. Still(P1) → 1.12 K / 0.55 mbar. |
| 1550 | V6 → 100.%. Condenser(G1) peaks at 167 mbar. MC(H35) → 0.13 mK. Still(P1) → 1.06 K / 0.16 mbar. |
| 1600 | Open V14 to pull the rest of the mixture out of the dump into circulation. Still peaks at 110 mbar, Condenser peaks at 226 mbar, MC peaks at 103 mK, then all relax again. 1K → 1.56 K / 10±0.5 mbar. |
| 1613 | Plug in DCRCs 1 and 3 |
| 1630 | Still = 0.60 mbar. Close V14 |