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2016/12/12 (Monday)

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Setup: DIB1/3/4 → 3.2 MHz filters → cables 1,2,3 → HV board inputs 1,3,2 → HV board outputs 1,2 → DCRC55(1)/50(3)
0845 Main bath = 72.3%
0850 Looking at phonon channels, several seem to have fallen into superconducting. Detector was at high bias a couple of days ago and hasn't been flashed since. So let's do that first.
0852 Flash detector for 30 s
0925 Finish microIbIs measurement at 0V. Vbias values are 25-125 mV lower than Dec 6 0V results, pretty close to the Dec 10 0V results.
0932 Dial HV up to 105 V. Noise is higher but pulses still present. Will leave it prebiased for 5 minutes.
0937 Dial HV down to 90 V
0945 HV = 90.0 V, Vtest = 10.5 mV → Vdetector = 85.4 V
0945 Pulses on the three DCRC1 channels look good, but on the two available DCRC3 channels they are distorted.
DCRC3pD pulses at 90V
1000 Adjusting the DCRC3 channels (pC and pD) to QET biases above the oscillating regime improves their pulse shapes, although the pulses now look smaller - they are probably close to normal, not a very sensitive part of the transition. But we'll try some data like this.
channel std QET bias new QET bias
DCRC3pC 165 188
DCRC3pD 202 240
We'll trigger on a more sensitive channel, DCRC1pB, try 15 threshold. That's the second ring channel.
1007 Start a sequence 1-hour series of 90V data with Frontend Gain = 5, OG = 2, DCRC3pB intentionally railed, with 1000 beginning randoms, with no flashing in between series, and a 15ADC bin threshold trigger on DCRC1 pB.
1015 After randoms, there seem to be no triggers. I think I know why - Anthony disabled triggering from DCRC1 for some reason. Will have to fix that. For now will try triggering with DCRC3.
1018 Stop sequence
1020 Start a sequence 1-hour series of 90V data with Frontend Gain = 5, OG = 2, DCRC3pB intentionally railed, with 1000 beginning randoms, with no flashing in between series, and a 15ADC bin threshold trigger on DCRC3 pC.
1032 Data looks OK but trigger seems too high, would like to get smaller pulses. Adjust DCRC3pC trigger threshold down to 12.
1041 Trigger still seems too high. Adjust DCRC3pC trigger threshold down to 9.
1058 Trigger still seems too high. Adjust DCRC3pC trigger threshold down to 6.
1110 Current triggering level seems OK, but DCRC3pC has some double pulse shapes, so we tend to get two triggers. Not great. Meanwhile Anthony says that he has reenabled DCRC1 triggering. So we'll stop this run and trigger on DCRC1pB (which is Side1pB, the second ring).
1115 Start a sequence 1-hour series of 90V data with Frontend Gain = 5, OG = 2, DCRC3pB intentionally railed, with 1000 beginning randoms, with no flashing in between series, and a 10ADC bin threshold trigger on DCRC1 pB.
1120 Triggering is not working. When I turn the DCRC3pC trigger back on, it starts triggering again.
1123 Go back to triggering on DCRC3pC with threshold = 6. Now it's the same configuration as with the (end of the) _1020 series.
1131 Tower/MC/Coldplate = 33.1/35.8/216 mK, Still = 1.20 K / 110 μbar, G1/G2 = 190/175 mbar, 1K Pot = 1.67 K / 24 mbar. MB = 68.2%. Boil off rate: pretty close to slow mode.
1145 Anthony told me that we need to restart the triggerfe2 program in order to reenable DCRC1 for triggering. So we'll stop this sequence and try that.
1147 Stop data sequence
1150 Stop triggerfe2, towerfe3, and dcrc_driver programs, then restart them
1149 Start a sequence 1-hour series of 90V data with Frontend Gain = 5, OG = 2, DCRC3pB intentionally railed, with 1000 beginning randoms, with no flashing in between series, and a 10ADC bin threshold trigger on DCRC1 pB.
1439 Stop data
1440 HV = 90.0 V, Vtest = 11.2 mV → Vdetector = 85.1 V
1455 Finish microIbIs measurement. The Vbias values are on average 85 mV higher than earlier today at 0V, except that DCRC3pD is an outlier at 570 mV higher than earlier today.
1500 Dial HV down to 0V.
Checking Vtest after dialing down to 0V shows -75 mV but falling, so I guess something is discharging. DCRC3 channels are still pretty ugly.
1510 Vtest down to around -4 V. DCRC3pC pulses still pretty bad (at standard QET bias = 165), pretty big 10kHz oscillations. DCRC3pD pulses also still bad.
1525 Finish microIbIs measurement. DCRC1 Vbias values are lower than they were at 0V earlier today, by 10-20 mV. But DCRC3pC is the same as earlier, and DCRC3pD is 575 mV higher, i.e. the same as it was at 90V. It seems to be semi-permanently messed up.
1530 Flash detector for 30 s
1555 Tower has cooled to 33.6 mK. Now DCRC3pC is in strong 10kHz oscillation, but pulses look mostly OK. DCRC3pD shows no pulses at the moment. Snapping DCRC3pD brings pulses back but many are distorted. Then after a few minutes the pulses are gone completely again. It's a mess…
1629 Double check SQUID settings, they seem to be the same ones we've been using successfully for HV up to now. Snapping DCRC PC/D and slowly bringing QET bias back down brings back pulses, but many look monstrous. DCRC3PC seems to have a little 10kHz in it still too.
1715 After ZAPping the SQUIDs, all channels look ok again after restoring settings, except the two DCRC3 channels pC and pD seemed to fall into s/c at their standard QET biases but they are ok at 5 uA higher (pC/D = 170/207).
1720 Fill LN2 cold trap full.

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