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2021/02/02 (Tuesday)

Previous Day

  • Lab in-person: Zach
  • Virtual partner: Matt, Derek
Status Run 74 prep. Main bath is up, need to finish tightening screws.
1140 Zach enters lab
1142 Begin filling LN2 cold trap dewar.
1143 Turbo on IVC = 19 nbar
1207 Start cryocleaning mixture through LN2 Cold Trap 1, V6 = 12.3%
1211 Increase V6 → 12.4% to restart flow
1220 Increase V6 → 12.5% to restart flow
1232 Increase V6 → 12.6% to restart flow
1245 Increase V6 → 12.7% to speed up flow
1315 Stop cleaning through Trap 1 after 60 min. G2 flow pressure was 575-760 mbar. Pump mixture to dump.
Removed 23.5 mbar.
Tried tightening the MB screws, but there were some problems. Tightened the small screws - then tightened the medium screws, which were pretty loose. This closed the gap enough that the small screws were raised up, with the washers loose beneath them. But only some of the small screws could be tightened further.

Perhaps tomorrow we should try readjusting the brackets that fix the fridge to the stand. The logical way to do this is to remove the small screws, tighten the medium and large ones completely, than loosen the brackets and try to adjust to line up the small screws. Worth a try I guess.
1400 Start cryocleaning mixture through LN2 Cold Trap 2, V6 = 12.4%
1405 Increase V6 → 12.8% to restart flow
1410 Zach exits lab
1450 Increase V6 → 12.9% to restart flow
CRAP! I opened V13a by mistake instead of V13b. This let some mixture into warm, dirty Trap 1. We'll need to cool that trap again and pump it out to the dump.
1505 Increase V6 → 13.0% to speed up flow
1515 Stop cleaning through Trap 2 after 75 min. NOTE: accidentally let some mix into warm, dirty Trap 1. G2 flow pressure was 565-640 mbar. Pump mixture to dump.
Removed 8.5 mbar.
1545 Turn off 3He pump
Note that after the first cleaning, Dump rose to 730 mbar after pumping mixture back to dump. After this second cleaning it only went to 720 mbar. So 10 mbar got released into Trap 1.
Tomorrow: take Trap 2 out of bath to warm up, put Trap 1 into bath to cool again, pump Trap 1 to dump, then remove Trap 1 to warm up. Then can pump out both traps.

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