2022/07/30 (Saturday)
- Lab in-personnel: Matt, Giulia, Shubham
| 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. |
| Fridge failure five days ago, looks like an impedance blockage. Two days ago at 110 K the impedance blockage was gone. Recooling: did LN2 transfer yesterday | |
| 1025 | MC(Cernox)/Sorb = 79.0/128 K, IVC = 2.5 mbar, G1/G2 = 602/546 mbar |
| 1035 | Start pumping out IVC with Scroll pump. At <0.1 mbar switch to Turbo pump. |
| 1035 | Begin blowing out LN2. Main bath (G3) → 260 mbar+1atm |
| He cylinder is low, will need to swap it soon | |
| 1040 | 63 nbar. With Turbo valved out for 1 minute, IVC = 0.74 ubar |
| I'm skipping the leak check during blowout. Instead I'll just monitor the IVC pressure. | |
| 1040 | Pump mixture out of fridge and LN2 Trap 1 into dump |
| 1045 | Switch to new He cylinder. MB → 582 mbar+1atm |
| 1045 | IVC = 0.63 ubar |
| 1055 | IVC = 0.63 ubar. MB = 564 mbar+1atm |
| Throughput test procedure, Cold Trap 1: |
- All mixture in dump, LN2 trap 1 cold, condenser & still valves open (3He pump on - optional)
- Open V9, V13a, V12a+speedivalve, V3. Wait for G1 to be close to G2 (within 100 mbar).
- Close V12a+speedivalve and V3, open V1
- monitor G1
| 1055 | Perform mixture throughput test at MC = 77 K using above procedure with 3He pump on. Let G1 rise to 543 mbar before Step 3, then it falls to 69 mbar, then rises. Throughput = 40.8 mbar/min. A little lower than last time, 2022 March 19 |
|---|---|
| 1100 | IVC = 0.86 ubar. MB = 562 mbar+1atm |
| 1105 | Fill LN2 cold trap bath |
| 1105 | IVC = 1.00 ubar. MB = 565 mbar+1atm |
| a little rise in IVC. But upper parts are probably getting warmer. (Sorb temperature is rising) | |
| 1110 | Open mixture to both sides of the fridge and cold LN2 Trap 1. Turn off 3He pump. |
| 1110 | IVC = 1.00 ubar. MB = 200 mbar+1atm and falling, blowout is about finished. |
| 1110 | Stop LN2 blowout |
| 1125 | IVC = 1.4 ubar, Sorb = 129.3 K and rising |
| 1125 | remove hose from MB LN2 fill pipe, remove fill pipe from cyostat and put stopper in port, for MB pumpout |
| 1125 | Start pumping out main bath with scroll pump. Taking longer than usual to fall to 1 mbar. After 12 minutes it got to 3 mbar, then actually rose a little. Maybe I didn't wait quite long enough to end the blowout. |
| 1140 | IVC = 1.6 ubar, Sorb = 130.4 K and rising |
| 1145 | MB = 3.6 mbar and flat. I guess we'll try to proceed normally from here. Hopefully not too much LN2 sitting at the bottom of the MB. |
| 1145 | Let about 0.5 bar He into MB. Then pump it out again with Scroll pump (we'll try a flush) |
| 1200 | MB is stuck at 3.6 mbar again. OK we'll try to proceed, hopefully the LHe transfer will be OK |
| 1200 | Pressurize MB with helium to 300 mbar above 1 atm. But then it starts to fall. Maybe the MB isn't well-sealed and that's why the pressure didn't go as low during pumpout. The right port at the top now has an o-ring nut with a stopper in it, maybe that's a little leaky |
| 1205 | Isolate MB by closing V1a. Pump out line to the G3 volume with Scroll Pump. Isolate pump, then open 1K Pot speedivalve to check pressure: ~0.036 bar on mechanical gauge, P2 off-scale. Then pump out 1K Pot (needle valve closed) with Scroll Pump to 0.032 mbar on P2. Then close 1K Pot speedivalve and V4a. Open V1a again to monitor bath pressure. |
| 1215 | IVC = 2.2 ubar, Sorb = 132.6 K and rising |
| 1220 | Let 63 μbar He exchange gas into IVC. |
| 1224 | Start initial LHe transfer |
| 3He pump is off, we'll leave it off during transfer | |
| 1230 | MC(Cernox)/Sorb = 79.4/137.2 K, IVC = 63 μbar, G1(fridge) = 597 mbar. G3(MB) = 568 mbar+1atm |
| Switch on resistance autorange on LakeShore 370 (so that the Cernox temperature doesn't peg) | |
| 1245 | MC(Cernox)/Sorb = 75.4/118.4 K, IVC = 22 μbar, G1(fridge) = 589 mbar. G3(MB) = 340 mbar+1atm |
| 1300 | MC(Cernox)/Sorb = 64.1/74.3 K, IVC = 12 μbar, G1(fridge) = 530 mbar. G3(MB) = 498 mbar+1atm |
| 1315 | MC(Cernox)/Sorb = 53.6/9.7 K, IVC = 10 μbar, G1(fridge) = 497 mbar. MB = 26.1% / 406 mbar+1atm |
| 1330 | MC(Cernox)/Sorb = 45.9/7.3 K, IVC = 8.6 μbar, G1(fridge) = 461 mbar. MB = 50.0% / 406 mbar+1atm |
| 1342 | MC(Cernox)/Sorb = 40.0/7.0 K, IVC = 7.4 μbar, G1(fridge) = 457 mbar. MB = 68.3% / 377 mbar+1atm |
| 1352 | MC(Cernox)/Sorb = 32.3/6.7 K, IVC = 7.4 μbar, G1(fridge) = 455 mbar. MB = 89.5% / 475 mbar+1atm |
| 1402 | MC(Cernox)/Sorb = 18.9/6.1 K, IVC = 100 μbar, G1(fridge) = 483 mbar. MB = 75.6% / 504 mbar+1atm |
| 1411 | MC temp is below 10 K, open turbo to IVC. IVC pressure hit 2.5e-3 mbar after about a few minutes. |
| 1413 | MC(Cernox)/Sorb = 4.4/5.6, IVC = 0.86 μbar, G1(fridge) = 475 mbar. MB = 62.8% / 540 mbar+1atm |
| 1432 | End LHe transer @51.5% |
| 1440 | MC(Cernox)/Sorb = 4.24/5.3, IVC = 10 nbar, G1(fridge) = 512.5 mbar. MB = 51.5% / 149.7 mbar+1atm |