2022/08/27 (Saturday)
- Lab in-personnel: Matt
| Status | Run 76 in progress |
|---|---|
| Setup | Cables 2/3/1 → diverter/nothing/nothing → Side2-readout HV CONN 1/3/2 → HV 1(L)/2(R) → DCRC50(3)/DCRC55(1), DCRC33(2)→HV control, NaI trigger signal → DCRCX(4) Lead/poly shield fully assembled. Boron-filled socks covering NaI detectors. PuBe behind lead wall on West side of lead/poly shield. |
| Second day after 2nd 5K pumpout. Temperature spikes are plentiful but detector didn't show signs of problems with helium films yesterday. | |
| 0915 | MC base is around 29.1 mK but it's spiking all the time, peaking between around 31 and 38 mK. |
| 0925 | Take a look at phonon channels - they still look pretty good. Baselines around -0.80 V where I set them yesterday, healthy pulses in all channels. |
| 0935 | Dial HV up to -230V nominal, -228.5V actual, for 15% prebias (using RootSequencer) |
| Vtest rose to around -260 mV then started to fall, but then popped back up to -312 mV and stuck there. That's high leakage - only 40% of the bias is on the detector. | |
| 0942 | Dial HV down to -200V nominal, -198.3V actual |
| 0945 | HV = -198.3 V, Vtest = -214.9 mV, high. Ileak = -236 uA. Vdetector = -103.7 V, only 52% of HV. This does not improve after a few minutes, actually gets a bit worse. |
| Let's try dialing HV down to around -100V | |
| 0950 | Dial HV down to -100V nominal, -97.8 V actual |
| 0955 | HV = -97.8 V, Vtest = -26.4 mV, Ileak = -29.0 uA, Vdet = -86.2 V (88%). After a few minutes leakage starts to get a bit better. |
| Let's see how low we have to go to get Vdet = 90% HV | |
| 0957 | Dial HV down to -90V nominal, -88.0 V actual |
| 1005 | HV = -88 V, Vtest = -15.7 mV, Ileak = -17.3 uA, Vdet = -81.1 V (92%). |
| OK, let's maybe try some data like this. | |
| 1010 | Check phonon channels. All look fine except DCRC1pA (Side2pC), baseline is lower and pulses look bad, weak and distorted. |
| 1015 | Dial HV down to 0V |
| 1105 | DCRC1pA still looks bad. Zap SQUIDS with DCRCs1&3 |
| 1125 | Readjust phonon offsets, get all baselines close to -0.80 V. All channels look good. |
| 1134 | Dial HV up to -109.25V nominal, -107.2V actual, for 15% prebias (using RootSequencer) |
| 1143 | Dial HV down to -95V nominal, -92.9V actual |
| 1147 | HV = -92.9 V, Vtest = -19.7 mV, Ileak = -21.6 uA, Vdet = -84.3 V (91%). |
| Phonon channels look ok, baselines slightly elevated | |
| 1153 | Start -84.3 V PuBe data series 91 min long, with 1000 initial randoms, 5 Hz in-run randoms, trigger on DCRC1pB threshold 10. Start series with the Start Button |
| 1220 | HV = -93.0 V, Vtest = -19.3 mV, Ileak = -21.3 uA, Vdet = -84.4 V (91%). |
| 1330 | Dial HV down to 0V |
| 1620 | MC/Coldplate = 29.4/150 mK, Still = 1.14 K / 0.085 mbar / 0 mW, G1/G2 = 167/165 mbar, 1K Pot = 60° / 1.63 K / 22±2 mbar, MB = 29.4 % |
| 1620 | Fill LN2 cold trap bath |
| 1626 | Begin LHe transfer @ MB = 29.4% |
| 1712 | End LHe transfer @ MB = 94.3% |
| 1725 | Forgot to open 4He pump exhaust to Recovery when I cooled down from the 5K pumpout. So recovery efficiency was only 75% instead of usual 95% |