| | Setup: iZIP mode, DIB1/2/3 → cables → 3.2 MHz filters → DCRC55/33/50 |
| | Cf source near detector for overnight activation. |
| 0815 | Tower/MC(H35)/MC sensor/Cold Plate = 35.2/28.6/41.2/156 mK, Still = 1.08 K / 0.095 mbar, G1/G2 = 120/125 mbar, 1K Pot = 1.55 K / 4 mbar, Main bath = 24.0% |
| 0830 | Fill LN2 cold trap Dewar |
| 0832 | Start LHe transfer at 20.3% |
| 0954 | End LHe transfer at 90.4% |
| 1120 | 1KPot is still running quite low. Try closing needle valve completely and reopening a couple of times. Open it to about 45 degrees. |
| 1240 | 1K Pot temperature: 1.473K, P2: 2.2mbar. Still running low. I now realize that we haven't been recovering the exhaust of the He4 pump, which shouldn't be affecting why the 1K Pot pressure keeps dropping, but who knows. Switch He4 pump exhaust to recovery and see if that affects the pot. |
| 1250 | 1K Pot temperature: 1.453K, P2: 1.5mbar. Looks like it's still dropping. Open needle valve another 1/8th of a turn. |
| | Temperature spikes up to ~2K, and P2 goes off scale. Then drops back down to ~1.83K and 120mbar. Then starts rising. Looks like it's oscillating for now. |
| 1300 | 1K Pot temperature has settled ~1.75K and P2 at ~33mbar. The tower temperature was gradually increasing while the 1K Pot dried up, but it dropped when the needle valve was opened, and it's held steady at ~36mK now. |
| 1320 | Place Cf source back in safe. |
| 1325 | 1K Pot temperature has dropped to ~1.62K and P2 is at 6.0mbar. Tower temperature has risen to 38mK and is still gradually rising. |
| 1407 | 1K Pot temperature continued to drop to ~1.58K, P2: 4.0mbar. Tower temperature had actually decreased to ~37.6mK. Open needle valve more to see if we can get to a point where the 1K pot stays higher. |
| 1435 | Start looking at pulses to see what state Midas left them in. On DIB 1, there's 250Hz noise. Let some pressure out of He dewar to see if that helps. |
| | Initially it seems like the sinusoidal noise went away, but it comes back periodically. |
| 1443 | When switching to view pulses on DIB2 (DCRC33), Detector Readout wouldn't update the displays. Had to WR 15 0, WR 15 20 to telnet session in order to get displays to update. All four channels on DIB2 are railed. |
| 1449 | When switching to view pulses on DIB3 (DCRC50), Detector Readout wouldn't update the displays. Had to WR 15 0, WR 15 20 to telnet session in order to get displays to update. All phonon channels except phC on DIB3 are railed. |
| 1452 | 250Hz noise still present on all DIBs. (LHe level at 86.4%) |
| 1507 | At some point during our 250Hz noise investigations, Detector Readout VI froze as it had done yesterday. It was looking at DIB3 (DCRC50) at the time. Abort and rerun the VI. |
| 1530 | Listening to the vibrations on the top of the fridge platform and comparing to a tone generator, estimate that the frequency there is about 104-105 Hz. Measured the frequency of the noise in the phonon pulses: it's close to 208 Hz, i.e. the first harmonic of the fridge vibration. |
| 1535 | Release pressure from top of main bath again, with level at 84.1%. Then plug it again. 250 Hz noise goes away, at least for a couple of minutes… |
| 1538 | Fridge frame no longer vibrating to the touch, and sinusoidal noise hasn't shown back up on pulses. |
| 1540 | Establish timing link w/ DIB1 (DCRC55) as master. |
| 1542 | 1K Pot temperature had dropped to ~1.5K and P2 at 2.2mbar. Open needle valve even more. |
| 1545 | Set phonon trigger thresholds to following ADC bin values: |