2020/09/13 (Sunday)
- Lab in-person: Matt
- Virtual partner: Pramod
| Setup | Run 73. DIB 1/3/4 → Stripline 43/48/41 → pi-filters 1/2/3 → Cable 3/1/2 → nothing/nothing/accessory_interposer → HV_Conn 1/3/2 → HV 1/2 → DCRCX(4)/DCRC55(1)-master; DCRC33(2) → HV control. DCRCs on overnight. Lead/poly shield erected (4 lead walls, 2 poly walls). |
|---|---|
| Two days ago the 1K Pot started acting up. Seems partially blocked. Now the Tower temperature is elevated and rather unstable. | |
| 0844 | MB = 36.0% |
| 0950 | Tower = 59 mK, currently wiggling around between 59 and 60 mK |
| 0950 | 1K Pot = 1.41 K / 2.4 mbar. Pressure is very constant, which is generally a bad sign. |
| 1400 | Tower = 59.0-60.5 mK, continues to meander but has stayed in that range for a few hours. |
| 1244 | MB = 30.5% Looks like MB is falling more slowly, probably because the 1K Pot pressure is so low. |
| 1415 | Checking channels. Spiky-trigger problem is not as bad today as yesterday. At trigger threshold = 8 about 25% of triggers are spiky noise. But at thresh=9 it's very few. |
| 1430 | Start a 60 min series at HV = +300V, drifting 0.0262 V/s, prebias 15% for 2min, CDMS detector: Driver Gains = 1x, DCRC4/1 QET biases = (0,320,370,0)/(0,360,420,410)uA, Front-End Gains = (3/3/3)/(5/5/5) 1000 BOR & 5 Hz in-run randoms, trigger on DCRC1pD threshold = 9 Use Root sequencer, function drift_sequence(300,0.0262) |
| 1430 | Tower = 58.8 mK |
| 1430 | Vtest = 12.0 mV shortly after drift begins. Drift was set to start at +313.4 V. 1.5% HV loss. |
| 1530 | Series ends, no apparent lag. Vtest = 11.7 mV. HV at end of drift should be 407.7 V according to sequence, indicating 1.1% HV loss |
| 1530 | Tower = 59.7 mK. It wiggled around 58.7 mK for first 45 minutes then shifted up to 59.7 mK for the last 15 minutes. |
| 1550 | Matt enters lab |
| 1555 | 1K Pot = 1.42 K / 2.8 mbar. Unlike earlier today it is oscillating. Or actually pulsing, the weird sharp pulse every 5 minutes that I saw before. This gradually began around 14:30 and G1/G2 fell a little at the same time. Looks like maybe a corresponding small drop in Tower temperature. |
| 1600 | Open 1K Pot needle valve an additional 10 degrees. After a spike 1K Pot → 13 mbar. After a few minutes open it another 10 degrees. Another spike, → 32 mbar. Each time there was a sharp drop in temperature, but not very big. G1/G2 an Still pressures increased. |
| Just noticed that Still Pressure has been pulsing too, in sync with the 1K Pot. Min 0.05 mbar, pulses to 0.065 mbar. | |
| 1610 | 1K Pot = 24 mbar and falling, similar to yesterday. |
| 1610 | Tower/MC/Coldplate = 60.2/32.2/195 mK, Still = 1.46 K / 0.085 mbar / 0 mW, G1/G2= 245/224 mbar, 1K Pot = 1.62 K / 19±3 mbar. |
| 1615 | Turn on Still Heater → 7 mW. Still → 0.170 mbar. G1/G2 rise. |
| 1615 | Swap HV leads to -bias |
| 1620 | Fill LN2 cold trap bath |
| 1620 | After turning on Still Heater, Tower rose from 60 to 61 mK, then fell back to 60 mK, seems to not be going lower. No real improvement. G1/G2 have risen to 320/293 mbar. |
| 1620 | Turn off Still Heater. |
| OK, plan is to skip LHe transfer. Can keep circulating for now and take some more data, and move the source again, until the MB starts to run low. Then we should stop circulation and 1K Pot. To do this remotely: close V6, to allow mixture to expand into still line. Close V4a to stop pumping on 1K Pot. Will need to leave 1K Pot speedivalve and needle valve open. Pot and pumping line will be full of helium. | |
| 1630 | MB = 25.2% |
| 1635 | 1K Pot = 1.56 K / 8.5 mbar. Continues to settle downward. |
| 1635 | Check channels, they look about the same as earlier today |
| 1642 | Start a 60 min series at HV = -100V, drifting 0.0280 V/s, prebias 15% for 2min, CDMS detector: Driver Gains = 1x, DCRC4/1 QET biases = (0,320,370,0)/(0,360,420,410)uA, Front-End Gains = (3/3/3)/(5/5/5) 1000 BOR & 5 Hz in-run randoms, trigger on DCRC1pD threshold = 9 Use RootSequencer.c, function drift_sequence(100,0.0280) |
| 1642 | Tower = 62.0 mK |
| 1642 | Vtest = -4.4 mV shortly after drift begins. Drift appears to start at -107.2 V. 1.6% HV loss. |
| 1645 | Matt leaves lab |
| 1743 | Drift ends, no apparent lag. Vtest = -8.5 mV. HV at end of drift looks like -207.4 V, indicating 1.6% HV loss |
| 1743 | Tower = 62.0 mK. Climbed to 64 mbar up to 16 minutes into the series; then climbed a hill to 70 mK, then 47 minutes in it started falling again, ending at 62 mK. |
| 1730 | MB = 23.1%. Will reach 15% at around 10pm maybe. |
| 1830 | Arduino Editor is still connected to the Arduino. Do rd dwell, it says 15 ms. Must have reset when the computer rebooted this morning. Set Dwell to 40 ms. |
| Establishing communication with the source mover caused a temperature spike to 1.7 K. Then it cooled again. | |
| 1845 | Tower = 95 mK and cooling |
| 1845 | Move source -4×38 steps with 4 minute pause after each move, mvNwait -4 240 38 |
| This should move the source to y = -12.502 mm (not corrected for thermal contraction). Total sequence should take 2hr 32min, ending at 9:17 pm. | |
| first move spikes temperature to about 0.92 K. Later peaks at 1.1 K, minima at 0.8 K. | |
| 2030 | MB = 18.6% |
| 2155 | Tower = 75 mK, still cooling after end of source mover sequence |
| 2324 | Started a series at -100V, but messed it up - the pulse viewer was still going. And I hadn't set it back to in-run randoms. Abort sequence and dial down HV. |
| 2327 | Flash for 10 seconds |
| ok, it's late. guess that's the end of data taking. | |
| 1130 | Stop circulation: close V6 to let mixture expand into still line. After a few minutes, Still pressure increasing, Tower was cooling after flash but stopped at 85 mK then began rising. |
| 1135 | Still = 2.2 mbar, Tower = 140 mK |
| 1135 | Stop 1K Pot: close V4a, no longer pumping on 1K Pot. Pot pressure will equalize with Main Bath. 1K Pot temperature rising. |
| 1140 | G1/G2 falling. |