2022/11/07 (Monday)
- 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 W side of fridge. NaI scan in progress, not set up for coincidence data |
| Cooled to base two days ago after twentieth 5K pumpout. Before cooldown IVC was closed at 5K and with mixture in dump. | |
| Taking 0V SiHV-triggered data overnight | |
| 1240 | Phonon baselines are highly elevated, pulses are quite weak, triggers rare. MC base started to rise around 12:00, from around 29.4 to around 30.0 mK. |
| Dump sizes started deviating from normal around 10:52, first increasing above normal and varying a lot. At around 12:15 they started to fall off to a minimum. So: looks like phonon symptoms showed up around 43 hours after cooling to base. Contrast that to 1)normal, where we start the pot right after closing the IVC - that's around 55 hours, and 2)IVC closed for a day with mixture in fridge before starting the pot - that was around 36 hours. In 3)this case, with IVC closed for a day with mixture in dump, it's 43 hours, so about midway between the other two. Seems to suggest that we have leaks both from the dilution unit and from outside the IVC. CORRECTION: looking at this again later, I'm not sure how I got the number 36 hours for the hold time after the first test. It looks like that hold time was 44 hours, close to the 43 hours of the second test. That means having mixture in the fridge while the IVC sat closed for a day did not make the leak any worse than with the mixture removed. This suggests that, while warm at least, the leak is into the IVC from the exterior (lab air or MB) and not from the dilution unit. |
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| 1510 | Spent some time trying to get MIDAS to work on cdms2 running CentOS. A lot of it is working - could start a run without logging and see pulses on SQUIDtuningGUI.exe (note: needed this line to make that work: export MIDAS_SERVER_HOST=cdms2.spa.umn.edu:7071). (another note: browser should point to http://cdms2.spa.umn.edu:8082.) But couldn't write data because of permission issues. It seems that when we sudo into shared user spa-u-cdmssoft and check groups, we don't get the correct groups when we do it from cdms2, but we do get the correct groups from cdms1. |
| 1515 | MC/Coldplate = 30.2/151 mK, Still = 1.13 K / 0.110 mbar / 0 mW, G1/G2 = 118/95 mbar, 1K Pot = 45° / 1.57 K / 9.5±0.5 mbar, MB = 64.3% |
| 1515 | Fill LN2 cold trap bath |
| 1515 | DAQ programs are already off. Unplug DCRCs 1&3 |
| 1515 | Close V6 to stop circulation. |
| 1525 | V6 is now fully closed (light is off on IGH, Still pressure is rising, Condenser pressure falling). Turn off 3He pump |
| 1525 | Open V3 to let mixture from Condenser side into Still side. |
| 1525 | Close 1K Pot needle valve |
| 1535 | MC = 0.46 K |
| 1535 | Turn on Still and MC heaters to 20 mW each |
| 1540 | Close 1K Pot speedivalve, V4a, 4He pump inlet valve. Turn off 4He pump. Close recovery valve to 4He pump outlet. NOTE: remember to open recovery valve when the pump is turned back on. |
| 1635 | MC/1KPot = 3.91/3.97 K. G1(fridge) = 781 mbar. |
| 1635 | Open V9 to release pressure into the dump. |
| 1725 | MC/1KPot = 5.53/4.37 K, pretty flat |
| 1730 | Check pressure in IVC: 0.25 ubar. Start pumping out IVC with turbo pump. |
| 1933 | Tower = 10.03 K. Turn off MC and Still heaters |