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2020/03/17 (Tuesday)

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Setup Run 72. DIB 1/3/4 → Stripline 43/41/48 → Cable 3/2/1 → nothing/nothing/accessory_interposer → HV_Conn 1/3/2 → HV 1/2 → DCRCX(4)/DCRC55(1). Lead/poly shield erected (4 lead walls, 2 poly walls).
Status Second Run 72 circulation attempt failed, helium in IVC. Warming up again.
Some helium in IVC and cryostat vacuum jacket. 1K Pot needle valve open. All mixture in dump. LN2 Trap 1 needs to be cleaned. MB recovery valve open. New helium cylinder ordered, should pick it up from gas room. Plan is to try to fix leak at top of stripline tube.
0217 Recovery meter = 343774 cuft (at 2:17:19). Rate = 0.047 cuft/hour
0830 MC(Cernox) = 182.9 K. G1/P1(fridge) = 0.3/0.75 mbar.
0903 Recovery meter = 343774.25 cuft (at 9:03:14). Rate = 0.034 cuft/hour
1120 MC(Cernox) = 190.2 K. G1/P1(fridge) = 0.3/0.75 mbar.

Todo list for today - coming in during the COVID-19 hibernation:

  1. Get helium cylinder from gas supply room
  2. Fill IVC with helium to speed warmup
  3. Close 1K Pot needle valve
  4. Pump out fridge, then close fridge valves
  5. Warm up and pump out LN2 Trap 1
  6. Consider adding more gas to cryostat vacuum jacket
  7. Consider closing main bath recovery valve. Alternatively could allow it to slowly push gas to recovery, and maybe ask Mike to close it later.
  8. Print and post lab hibernation signs (PAN 43, 443… also LIGO?)
  9. Go through the U's Hibernation Plan:
    1. add radiation sign to Howitzer
    2. close gas cylinders
    3. get the power strips off the floor. Will need to turn off turbo pump, probably.
    4. “secure” lab laptop. (Maybe take it home?)
1240 MC(Cernox) = 193.4 K. G1/P1(fridge) = 0.3/0.75 mbar.
1300 Cryostat vacuum jacket = 0.074 mbar.
1300 Let 3.4 mbar N2 gas into vacuum manifold. Then open cryostat vacuum jacket valve to let this into the vacuum jacket. Vacuum Jacket → 0.22 mbar.
1310 IVC = 4.0 mbar
1315 Let 0.65 bar N2 gas into IVC.
1330 Lift all power strips off the floor. Raise computers off the floor, at least 4 inches, using wood boards. This is recommended from the U for lab “hibernation”, to protect against possible flooding.
1355 Start pumping out fridge (both sides) with Scroll pump. Pump for 30 minutes, P1 falls to 0.11 mbar.
1405 Close gas cylinders as per the U guidance. Closed the cylinder valves and also the valves below the regulators.
1405 MC(Cernox) = 195.7 K. Warming curve slowed down after adding N2 to the IVC. I guess maybe the IVC walls were colder than the fridge itself.
1410 Close 1K Pot needle valve. This could result in an overpressure when it warms up, as much as 1.5 Bar (7.5 PSI). But we know the relief valve works reliably at 5 PSI so it should be OK.
1414 Recovery meter = 343774.4 cuft (at 14:14:06). Rate = 0.028 cuft/hour
1425 Check warm LN2 Trap 1: 9.9 mbar. Pump out with Scroll pump.
1510 MC(Cernox) = 197.9 K.
1930 MC(Cernox) = 209.2 K.
2154 Recovery meter = 343774.65 cuft (at 21:54:06). Rate = 0.028 cuft/hour
2200 MC(Cernox) = 215.6 K.

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