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2023/10/30 (Monday)

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  • Lab in-personnel: Zach
Status Mixture in fridge with 3He pump off, 4He pump off
1433 Fill LN2 cold trap bath from 5L dewar
1440 MC(Cernox)/Sorb/1K Pot = 5.39/9.2/5.39 K, G1/G2 = 536/487 mbar, MB = 31.4%
1442 Turbo on IVC = 16 nbar. With Turbo valve out for 1 minute IVC = 100 nbar
P2 is up again after Himangshu pumped out the 1kpot on saturday, need to swap back to the scroll pump and redo it
1446 Pump out line leading to 1K Pot with scroll pump (V4a open, 1kpot speedivalve closed). Then switch the line over to the 4He pump. Turn on 4He pump and make sure the pump exhaust is connected to recovery and open valve to recovery lines.
Accidentally opened V1A as well, was pumping on the main bath for a short period, oops
1517 Start LHe transfer @ MB = 30.2%
1519 Check pressure in 1K Pot by opening the 1kpot speedivalve with V4a closed: Mechanical gauge = 0.23 bar.
1522 Pump out 1K Pot by slowly opening V4a then the manual valve at the 4He pump until it just starts to make noise, once it quiets down somewhat open it up a little more. continue this until the valve is fully open.
Leaving mixture in the fridge when starting 1K pot
1529 Open 1K Pot needle valve → 15° (half unit on the needle marks). 1K Pot → 3.20 K / 5 mbar.
Temps start to drop, mixture pressure starts to drop
1535 Open 1K Pot needle valve → 30°. 1K Pot → 2.63 K / 9 mbar.
1538 MC(H35) temp drops, flattens at around 3.2 K
1543 Open 1K Pot needle valve → 45°. 1K Pot → 1.85 K /30 mbar.
1552 MC(Cernox)/Sorb/MC(H35) = 2.70/4.0/2.70, 1K Pot = 1.69 K / 30 mbar. G1 (fridge+dump) = 195 mbar.
1600 End LHe transfer @ MB = 93.3%
1608 MC(Cernox)/Sorb/MC(H35) = 2.12/4.0/2.09, 1K Pot = 1.56 K / 12 mbar. G1 (fridge+dump) = 62 mbar.
1611 Close V3 and V9, leaving 64.5 mbar in the dump. Turn on 3He pump.
1613 Start circulation through Trap 1. V6 → 12.6%. Condenser(G1) peaks at 268 mbar. P2 jumps to max before falling again. MC(H35) → 1.20 K. Still(P1) → 1.36 K / 6.5 mbar.
1620 V6 → 13.0%. Condenser(G1) peaks at 79 mbar. MC(H35) → 0.89 K. Still(P1) → 1.07 K / 2.4 mbar.
1623 V6 → 13.4%. Condenser(G1) peaks at 110 mbar, still rising. MC(H35) → 0.76 K. Still(P1) → 1.17 K / 2.6 mbar.
1630 V6 → 13.8%. Condenser(G1) peaks at 118 mbar. MC(H35) → 0.58 K. Still(P1) → 1.15 K / 1.9 mbar.
1635 V6 → 14.4%. Condenser(G1) peaks at 115 mbar. MC(H35) → 0.40 K. Still(P1) → 1.14 K / 1.0 mbar.
1640 V6 → 15.0%. Condenser(G1) peaks at 108 mbar. MC(H35) → 0.24 K. Still(P1) → 1.15 K / 0.55 mbar.
1645 V6 → 100.%. Condenser(G1) peaks at 103 mbar. MC(H35) → 0.15 K. Still(P1) → 1.10 K / 0.16 mbar.
1650 Open V14 to let the remaining mix out of the dump and into circulation. P1(Still) peaks at 1000 mbar then falls again. MC(H35) peaks at 146 mK. Condenser peaks at 136 mbar.
1726 Still (P1) < 1 mbar, close V14
1727 Decrease the 1K Pot needle valve → 37.5°, P2 → 30 mbar, 1kpot = 1.65K
1728 Tower(U28)/MC(H35)/Coldplate = 88/32.6/146 mK, Still(P1) = 1.11 K / 0.11 mbar / 0 mW, G1/G2 = 76.3/77.8 mbar, 1K Pot(P2) = 37.5° / 1.65 K / 32 mbar, MB = 91.8%

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