2021/02/11 (Thursday)

Previous Day

• Lab in-person: Matt
• Virtual partner:

Status	Run 74 prep. Main bath is up. Need to do more cryocleaning and prepare room-temperature circuit for HV biasing.
1200	Matt enters lab.
1235	Check contents of warm LN2 Trap 2: 5.0 mbar. Pump out with Scroll Pump
1305	Check contents of warm LN2 Trap 1: 9.7 mbar. Pump out with Scroll Pump
1325	Work on diverter board for HV biasing. The plan is to use a second board, in series with the board that's already hooked up for the source mover. There is a biasing board used previously (in a 150mm run) with two coaxes and two resistors mounted. It's a 10 MOhm bias resistor and a 1 kOhm test resistor. So we just need to solder a lead to the appropriate bias wire and one to analog ground.
1335	Start cryocleaning mixture through LN2 Cold Trap 1, V6 = 11.3%
1340	Increase V6 → 11.4% to restart flow
1345	Increase V6 → 11.5% to restart flow
1355	Increase V6 → 11.6% to speed up flow
1415	Increase V6 → 11.7% to speed up flow
1440	Stop cleaning through Trap 1 after 65 min. G2 flow pressure was 560-770 mbar. Pump mixture to dump. Removed 6.5 mbar.
1445	Finish preparing HV diverter board. Bias connected to Pin 1 on Dsub, which is QET A Ret 1, which is what we have the Side2 electrode connected to. Switched off all phonon-related dip switches to break contact to detector - only LED, Q, FET related ones connected. Verified continuity between Side2 bias and the DIB2 charge channels by connecting board to Cable 3 and breakout box. Couldn't do a full checkout because some of the diverter board pins don't seem to connect well to the breakout box Dsub connector.
1545	Start cryocleaning mixture through LN2 Cold Trap 2, V6 = 11.8%
1555	Matt exits lab
1635	Increase V6 → 11.9% to speed up flow
1650	Increase V6 → 12.0% to speed up flow
1710	Stop cleaning through Trap 2 after 85 min. G2 flow pressure was 570-890 mbar (but toward the end began to rise to >1 bar). Pump mixture to dump. Removed 4.7 mbar.

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