2019/03/15 (Friday)
| 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) manual kepco 1kV power supply → HV input |
|---|---|
| 0905 | Tower/MC/Coldplate = 48.3/31.4/201 mK, Still = 1.85±0.20 K / 0.160 mbar, G1/G2 = 219/207 mbar, 1K Pot = 1.78 K / 17 mbar. MB = 71.0% |
| Tower essentially flat overnight with a few slow peaks, rising by about 0.5 mK then falling. | |
| 0915 | Fill LN2 cold trap bath |
| 1045 | Check channels, all show pulses and seem fine. |
| Plan: do another set of data while manually increasing HV bias 4 V/min. We will start data before applying bias, then at some point after we get to the start bias and start increasing, stop and restart run to get another set of randoms. | |
| 1102 | Start background series at HV = 0V, then applying 308 V CDMS detector: Driver Gains = 1x, DCRC4/3 QET biases = (415/370/420)/(400/370/420) uA, Front-End Gains = (4/2/3)/(10/15/10) 1000 BOR randoms, trigger on DCRC3pB/C threshold = 7/15 |
| 1104 | Increase bias to 350 V, then back it down to 308 V. Wait for Vtest to fall to 50 mV. |
| 1108 | Stop and restart data. |
| 1109 | Start at HV = 308 V, begin increasing +4V every 1 minute |
| 1120 | Vtest is staying around 55 mV |
| 1137 | At 420 V, Vtest suddenly started increasing dramatically. This worried us, so we backed off to 376 V. Vtest came back down. |
| 1140 | Some problems seen in the phonon channels. Some railed, some in oscillatory mode. Tower temperature has been increasing for last 20 minutes, and the rate of increase is rising. |
| 1142 | Stop data |
analysis: first look at this data suggests a noise width around 145 eV.
| 1150 | Tower has risen to 51 mK. Turning QET biases to zero one by one, trying to find the one that's screwing things up. |
|---|---|
| 1155 | All QET biases at 0 V but Tower temperature still increasing, now at 51.8 mK |
| 1155 | HV = 376 V, Vtest = 57 mV and steady. Bring HV back down to 0 V |
| 1200 | Tower temperature still increasing, 52.9 mK. Circulation pressures have risen too. |
| 1205 | Flash DCRC3/4 LEDs for 30 seconds. Tower rises from 53.2 to 56.0 mK then falls again. |
| 1220 | After the bump from the flash, tower temp continues rising as before. Now at 56.5 mK. Power down the DCRCs. |
| 1225 | After powering down DCRCs, Tower temperature is falling steadily. Circulation pressures also falling back toward their previous levels. |
| 1235 | Tower still cooling, now 51.3 mK |
| 1305 | Tower settling around 47.5 mK. Temperature and circulation pressures a little lower than this morning. |
| 1305 | Plug in power to the DCRCs, and restart the DAQ programs. Tower rises to 47.9 mK |
| 1310 | Zap SQUIDs. Tower rises to 51.6 mK, then settles at 48.6 mK. |
| 1325 | MB = 64.8% |
| 1545 | Start setting up DCRC2 for remote HV control |
| 1650 | MB = 60.0% |
| 1705 | Fill LN2 Cold Trap Bath |