2019/03/23 (Saturday)
| 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. PuBe source present in paraffin barrel behind lead stack. |
|---|---|
| 1305 | Tower/MC/Coldplate = 42.1/30.0/189 mK, Still = 1.8±0.2 K / 0.150 mbar, G1/G2 = 245/223 mbar, 1K Pot = 1.78 K / 16 mbar. MB = 68.3% |
| 1250 | Fill LN2 cold trap bath |
| 1445 | Switched back to the Fluke multimeter, going to reset QET biases, Tower temperature stable at 42.5 mK, MB = 66.9% |
| 1455 | Start 4 PuBe series at HV = 300→400V @ 5.4 V/min (18 min duration) with 1 minute 15% prebias CDMS detector: Driver Gains = 1x, DCRC4/3 QET biases = (410/370/430)/(430/390/420) uA, Front-End Gains = (4/2/3)/(10/15/10) 1000 BOR randoms, trigger on DCRC3pB/D threshold = 7/7 use sequence HVdrift_fast_4X300V_5p4VPM_prebias_15_1_dur_18min.msl |
| 1506 | So far so good, data has started, all channels look ok, leakage never went above 130 mV during the prebias step, temperature is mostly stable, raising a little bit (42.4 mK, was 42.1 mK) |
| 1522 | First series just finished, Tower = 42.7 mK, Vtest maxed out at 170 mV. This isn't so bad. Going to keep going so long as channels survive the flash and cooldown. |
| Tower temperature increased during the first series, rising about 1.5 mK, and stayed elevated. So probably at some point the QETs got into a bad state. | |
| 1540 | All channels look ok, temperature is stable again after the flash and Vtest never got out of hand. I'm going to let things go for now. -DS |
| 1640 | Second flash occurs after second series |
| 1830 | No change in bias or indication of a flash since 16:40. So probably MIDAS is frozen. We'll fix it tomorrow. |