2019/03/28 (Thursday)
| Setup | DIB1/3/4 → 3.2 MHz filters 2/3/1 → cable 3/1/2 → gender changer 3/?/2 → HVConn 1/3/2 → HV 1/2 → DCRCX(4)/DCRC50(3) DCRC33(2) → 1kV power supply → HV input Lead poly shield is erected, N/E/W walls complete, no poly or lead on S wall. |
|---|---|
| 0855 | Tower/MC/Coldplate = 40.0/29.7/189 mK, Still = 1.70±0.10 K / 0.150 mbar, G1/G2 = 268/245 mbar, 1K Pot = 1.78 K / 14 mbar. MB = 36.3% |
| 0910 | Fill LN2 cold trap bath |
| 1115 | Looks like at some time between 9:40 and 11:15 MIDAS completely crashed (?) - no MIDAS processes were running. Restarted MIDAS, looks fine… |
| 1115 | Shut down MIDAS again, to allow for a cdms2 reboot. cdms2 has been sluggish, which may be the reason for the MIDAS crashes. So maybe a reboot will help. |
| 1140 | cdms2 has been rebooted. |
| 1145 | Restart MIDAS and the DAQ programs. |
| 1150 | Start a test run and look at traces with SQUID Tuning gui, it's working. |
| 1332 | Begin LHe transfer @ MB = 29.7% |
| 1414 | End LHe transfer @ MB = 93.7% |
| 1630 | Tower = 40.0 mK |
| 1635 | MB = 91.6% |
| 1636 | At 16:36:20 start sequence to dial up HV from 0 to 400V at 1 V/s. |
| 1639 | At 16:39:42 HV reaches 100.3 V |
| 1643 | At 16:43:14 HV reaches 206.1 V |
| 1646 | At 16:46:32 HV reaches 305.4 V |
| 1649 | At 16:49:26 HV reaches 392.2 V |
| 1650 | HV reaches maximum of 399.2 V |
- By HV = 7 V, Vtest had risen to 10 mV
- By HV = 38 V, Vtest reached 15 mV
- then Vtest went up very slowly, reaching 18 mV at maximum (HV = 399.2 V)
- Vtest fell immediately after the rampup stopped. Within 20 seconds Vtest < 10 mV
- After 5 minutes Vtest settled around 8 mV
well this seems to be a huge improvement. Apparently disconnecting the unnecessary connections in the HV box works.
| 1655 | Tower = 40.3 mK |
|---|---|
| 1700 | Check the phonon channels - all look OK (except DCRC3pB which has not been working since yesterday). I think there's also pretty clear evidence of a voltage bias - e.g. some jagged noise |
| 1706 | Start sequence to dial down HV from 400 to 0V at 1 V/s. |
| 1711 | HV = 200 V, Vtest = -10 mV. Vtest fell to 0 as soon as the sequence started and has been drifting in to larger negative values. |
| 1710 | Fill LN2 cold trap bath |
| 1715 | HV = 100 V, Vtest = -15 mV. More/different breakdown noise seen in DCRC4pC, I think elevated baseline too. |