2022/11/02 (Wednesday)
- Lab in-personnel: Zach
| 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 W side of fridge. NaI scan in progress, not set up for coincidence data |
| Cooled to base yesterday after nineteenth 5K pumpout. | |
| As a fridge experiment, after the pumpout we isolated the IVC then left it closed for a day while still at ~5K. The question was whether the helium film symptoms would appear 14-15 hours after beginning circulation as usual, or whether the symptoms would begin earlier. The former would suggest a superleak, the latter a constant leak. As it turns out, symptoms have appeared early, though it doesn't look quite the same so it's maybe hard to pinpoint when they started. The earliest sign was 6:20 pm last night - the MC temperature had been slowly falling, then it rose from 28.7 mK to 29.0 mK over an hour - pretty subtle. Then starting at 7:20 pm a more significant excursion occurred, with the MC rising to 30.0 mK and then falling again. More frequent oscillations started at around 8:25 pm - the frequency looks similar to the familiar “spikes” though these didn't look spiky, more just wavy - though that might be how things start out. Small deviations at that time, between 28.8 and 29.2 mK. By 1:55 am it definitely looked like the familiar spikes. |
|
| 1055 | Baselines for DCRC1pA/B/D/DCRC3pA/B/D = -0.812/-0.813/-0.814/-0.812/-0.811/-0.810 V. These are down from the -0.800 V adjustments yesterday. I think we've seen this before - I remember thinking that maybe the detector keeps cooling for several hours after the MC has hit its minimum. |
| 1105 | MC base = 30.0 mK. Most spikes peaking below 32, some above 34 mK this seems more typical of two days after cooling to base (e.g. compare Oct 27 to Oct 26). |
| 1330 | DCRC1pA baseline = -0.817 V. Even lower. |
| 1505 | MC/Coldplate = 30.2/150mK, Still = 1.11 K / 0.080 mbar / 0 mW, G1/G2 = 152/146 mbar, 1K Pot = 45° / 1.57 K / 9.5±1 mbar, MB = 63.2% |
| 1507 | Fill LN2 cold trap bath |
| 1550 | Noticing that G1/G2 are strangely unstable. They are in an ok range, 120-150 mbar, but they've been wiggling which is unusual. |
| 1550 | DCRC1pA baseline = -0.815 V. |
| I want to monitor the baseline to see when helium films start killing the phonon channels, but I may not be able to keep checking the pulse viewer. So let's take some data in case I miss the transition, can look at the data later (or just see the file sizes fall). | |
| 1555 | Start 0 V PuBe data series 190 good min long, SiHV-triggered with 1000 initial randoms, 5 Hz in-run randoms, trigger on DCRC1pB threshold 10. Start series with the Start Button |
NOTE: in this series I didn't enable DCRC4 (NaI trigger info is not useful currently), so we will need to process it differently. I think we'll want processingUMNData.r76_HV2 and configUMNData.r75_HV1 |
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| DAQ crash, last non-empty dump was 190 at 19:08 | |
| 2132 | Start 0 V PuBe data series ## min long, SiHV-triggered with 1000 initial randoms, 5 Hz in-run randoms, trigger on DCRC1pB threshold 10. Start series with the Start Button |
| 2135 | DCRC1pA baseline = -0.809 V. |
| 2135 | MC base = 29.5 mK. Most spikes peaking below 32, some above 34 mK. Not much different from earlier today. |