2021/09/09 (Thursday)

Status	Run 74 in progress. First cooldown after IVC rebuild.
	Tower thermometer is reading high, probably this is a thermometer problem and the actual temperature is much lower. High noise in some of the charge channels.
	Setup: DIB1/2+acc → SL 41/43 → 3.2 MHz filters → cables 2/3 → nothing/~~Source_mover_board~~+HV_diverter_board → DCRC50(3)/55(1). Kepco 40V supplye → HV BNC. Lead shield erected, 4 walls. Currently both DCRCs are on.
	Position of Am source: y = 0.0 mm
0822	Tower/MC/Coldplate = 131.1/34.2/193.3 mK, Still = 1.39 K / 0.070 mbar / 0 mW, G1/G2= 291.7/265.9 mbar, 1K Pot = 1.56 K / 10±1 mbar. MB = 40.9%.
0828	Fill LN2 cold trap bath
0831	At 10kHz noise in DCRC3qI/qO/DCRC1qI/qO = 18/5.2/4.3/84 8e-6. This is q3/q1/q4/q2 At 3kHz (peak) noise in DCRC3qI/qO/DCRC1qI/qO = 140/25/20/560 e-6
	Noise is as slightly higher than yesterday.
1006	Start 45 min series of -8V/0V (bias applied after 60 sec), with 1000 beginning randoms, trigger threshold 150/50/35/350 on DCRC3qI/qO/DCRC1qI/qO, 5Hz in-run randoms, with 1.6384 ms pulses (8192 length) and 400 us prepulse (500 length). Use Sequencer script r74_takeandflash_dcrcbias.msl. This flashes for 30 seconds at end of series.
	This is a repeat of last night's data which I thought didn't write, but turns out it was just that lazy logger wasn't moving the data. Should restart MIDAS after this series completes.
1100	Restart MIDAS. Looks like lazy logger is running now.

07210909_1006. Charge collection efficiency is surprisingly low.

Same pattern as yesterday, with a decrease at the beginning and a small increase around 25 minutes

1510	Setting up to do a negative-bias breakdown test. We'll switch the Side 2 bias power supply to positive polarity to apply +bias to Side 2, increase the bias till we see breakdown, then back off again until breakdown disappears. We'll write the data to disk too, in case we want to look at it later and synchronize the data with the bias log data from the Omni_Viewer vi.
1514	Start ~8 min series of 0/+V breakdown test data with 1000 beginning randoms, starting at 0/0V then increasing steadily to 0/+30.9V (maximum), then decreasing back to 0V and leaving there a couple minutes, trigger threshold 50/100 on DCRC1qI only, 3Hz in-run randoms, with 1.6384 ms pulses (8192 length) and 400 us prepulse (500 length). Use Status page START button.
	So, at negative bias, we were able to increase to the maximum for the kepco supply, which is 30.9 V, with no breakdown.
1525	Flash DCRC1&3 LEDs for 30 seconds.
1557	Start ~7 min series of 0/+V breakdown test data with 1000 beginning randoms, starting at 0/0V then increasing steadily to 0/-15.6V (maximum), saw breakdown, decrease to 0/-13.6V, breakdown disappears, trigger threshold 100 on DCRC1qI only, 3Hz in-run randoms, with 1.6384 ms pulses (8192 length) and 400 us prepulse (500 length). Use Status page START button.
	So, at positive bias, we again see breakdown, arriving at an even lower bias than the last time on Aug 26.
1616	Begin LHe transfer. MB = 29.8%
1650	Finish LHe transfer. MB = 89.8%