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2024/09/20 (Friday)

Previous Day

  • Lab in-personnel: Himangshu
Status MC(H35) = 6.9 K. Closed IVC valves yesterday.
1000 Fill LN2 cold trap bath
1222 Refilled LHe as well (MB = 95%)
– (Already)Close IVC valves at top of fridge.
1225 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 = 100 mbar on G3.
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 starts to lower down, open valve all the way.
1239 Open 1K Pot needle valve → 15°. 1K Pot → – K / 20 mbar, Still = 11.1 K, Coldplate = 11.07 K
1248 Still = 7.94 K, Colplate= 10.4 K, MC temp dropping linearly.
1254 Still = 5.05 K, Colplate= 9.96 K, MC temp dropping linearly. MC = 6.4 K
1258 1K Pot needle valve → 10°. Trying to keep P1 closer to 10 mbar as we used to do in Run 76. P2 = 15 mbar
1315 Open 1K Pot needle valve → 15°. Still warmed up a bit Still=7.07 K, MC flat.
1323 Still = 4.38 K, Colplate= 9.19 K, MC temp dropping linearly. MC = 6.03 K
1333 Still = 3.49 K, Colplate= –K, MC temp dropping linearly. MC = 5.9 K
1333 Open 1K Pot needle valve → 30°(1 unit). P2 = 40 mbar
1345 Still = 3.26 K, Colplate= –K, MC temp dropping linearly. MC = 5.59 K
1442 Still = 2.96 K, Colplate= 3.99 K, MC temp dropping almost flat. MC = 2.94 K
1450 Close V5 and V9, leaving 150 mbar mixture in dump (G2)
1456 Turn on 3He pump. G1(condenser) → 250 mbar
1501 Start circulation through Trap 1. VT →openeing very slowly. Condenser peaks at 450 mbar. MC(H35) → 2.01 K. Still → 2.05 K / – mbar
1516 VT → more slowly. Condenser peaks at 500 mbar. MC(H35) → 1.33 K. Still → 1.84 K / 40 mbar
1524 After a few turns, G1 = 450 mbar, p1 = 1 atm, MC(H35) = 1.24 K, Still = 2.04 K
How to know if we have turned enough to cross the 100% mark? After turns, it won't have any effect on MC temp or P1. P1 hovers in the range 300-500 mTorr. MC flattening at 1.33 K
1543 Open V10 in steps, to pull the rest of the mixture out of the dump into circulation. Open V10 and wait a few seconds as P1 max out, Close V10, wait till P1 is in 300-500 mTorr range, repeat
1651 After repeating the above step 100 times or more, the MC temp shows values lower than 1K and Still closer to 1.11K.
1652 Open V10 completely this time, as all the mixture is in the circulation and G1 < 550 mbar. P1 will start to fall down after a few minutes.
1656 P1 is 300-500 mTorr range, Close V10

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