2020/02/25 (Tuesday)
| Setup | Run 72. DIB 1/3/4 → Stripline 43/41/48 → Cable 3/2/1 → nothing/nothing/accessory_interposer → HV_Conn 1/3/2 → HV 1/2 → DCRCX(4)/DCRC55(1). DCRCs on overnight. No shield. |
|---|---|
| overnight: tower temperature excursion at 6:40am for some reason, rose 67 mK then relaxed back to base by 7am. tower temperature falling at constant rate, 0.030 mK/hour, 0.72 mK/day |
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| 0855 | Tower/MC/Coldplate = 54.9/31.5/196 mK, Still = 1.57±0.05 K/ 0.200 mbar / 0 mW, G1/G2= 288/262 mbar, 1K Pot = 2.11 K / 24 mbar. MB = 68.5% |
| 0900 | Fill LN2 cold trap bath |
| 0915 | Open 1K Pot needle valve wider, 30° → 40°. 1K Pot settling at 2.20K / 36 mbar. Still rises to 0.22 mbar. Circulation pressures rise. |
| 1005 | Tower has risen to 55.4 mK, so I guess the pot adjustment is not an improvement. |
| 1100 | Get remote HV setup working, DCRC33(2) → 1kV power supply |
| 1125 | Crank the HV supply voltage up all the way, then calibrate the HV to the control voltage, save this as HV_DCRC2_control_cals_410V_200225.txt in MidasDAQ/online/scripts/pysequencer/HV_calibrations. Used the Fluke 87 multimeter to measure output voltage. |
| DCRC2QI (V) | HV (V) |
|---|---|
| 11.6 | 0 |
| 11.5 | 0.5 |
| 11.4 | 3.45 |
| 11.3 | 6.3 |
| 11.2 | 9.29 |
| 11 | 15.3 |
| 10 | 46 |
| 9 | 76 |
| 8 | 106.2 |
| 7 | 136.5 |
| 6 | 166.8 |
| 5 | 197.1 |
| 4 | 227.4 |
| 3 | 257.8 |
| 2 | 288.2 |
| 1 | 318.5 |
| 0 | 348.9 |
| -1 | 379.3 |
| -2 | 409.7 |
| 1245 | Connect HV output to HV box and try applying a bias. Watch the phonon channels and watch Vtest with the Keithley meter. Went as high as 167 V according to the calibration. Saw strong pulses. Occasionally jagged noise and high-ish / unstable Vtest, especially right after adjusting the bias, then Vtest would relax again. Pulses disappeared or became weak while Vtest was high, then appeared strong again when Vtest settled. Stable Vtest rose linearly with bias, about 9 mV at 167 V (so electrode voltage was around 163 V). Strangely the dial on the Kepco voltage supply always read 3 times higher than the calibration voltage (500V when we were at 167V according to the calibration). Should recheck calibration with different voltmeters. |
|---|---|
| 1250 | Take bias back to zero (adjusting DCRC2qI in steps of 0.1). Pulses continue to look strong, could be self-biasing now. |
| 1300 | Try a 10-second flash on DCRC1 - that should be the one with the LEDs. Temperature peaks at 500 mK. |
| 1315 | Checked HV calibration with multiple meters including the HP, all agree. So the Kepco dial is wrong. or - rather - we plugged into the Kepco incorrectly. Used GND and +. But should use - and +. Need to redo the calibration. |
| 1330 | Tower is back down to 56.3 mK, 30 minutes after the flash. Was 55.8 mK before flash. |
| 1400 | Redo calibration, this time with leads plugged into + and - on Kepco voltage supply. |
| DCRC2QI (V) | HV (V) |
|---|---|
| 11.52 | 0 |
| 11.5 | 0.4 |
| 11.4 | 4.3 |
| 11.3 | 8.6 |
| 11.2 | 13 |
| 11 | 22 |
| 10 | 65.1 |
| 9 | 108.6 |
| 8 | 152.1 |
| 7 | 195.6 |
| 6 | 239.1 |
| 5 | 282.6 |
| 4 | 326 |
| 3 | 369.6 |
| 2 | 413.1 |
| 1 | 456.5 |
| 0 | 500 |
| Note: often the voltage is a bit unstable. It would be stable within 0.1 V, then after a minute would start bouncing around by maybe 5V. It seems to happen more at the lower voltages. | |
| 1420 | Use HVscan.py to generate a sequence HVdrift_180V_41p5mVps_pre10-2_88min.msl. This should bias detector to 180 V after a 2 minute 10% prebias, then drift by 41.5 mV/s and run for 88 minutes. Then flashes 30 seconds and waits 30 minutes. Drift rate is simply taken from a Run 70 sequence. |
| 1441 | Start a series at HV = 180→399V, rate 41.5mV/s, 88 minutes, with 10% prebias for 2 minutes, flash at end with 30 min wait. CDMS detector: Driver Gains = 1x, DCRC4/1 QET biases = (na/360/430)/(360/420/440) uA, Front-End Gains = (na/3/3)/(5/5/5) 1000 BOR randoms, trigger on DCRC1pD threshold = 10 Use sequence HVdrift_180V_41p5mVps_pre10-2_88min.msl |
| After 7 minutes HV reaches the prebias voltage, 180-190 V on the Kepco dial. Vtest was mostly around 5 mV but frequently unstable, generally 0-10 mV | |
| 1452 | Data starts. Phonon channels look good. |
| Vtest is pretty unstable. | |
| 1455 | Now Vtest is stable at 2.1 mV. HV = 180V on Kepco. Tower = 56.1 mK |
| 1500 | Pulses on BatViewer look fine. Probably could reduce threshold, no small pulses really. |
| 1500 | Set ODB to take 10 Hz in-run randoms, we'll want these to check the noise width. Hopefully this will take. |
| 1510 | Vtest = 0-10 mV, Kepco = 200V, pulses on BatViewer look OK. |
| 1520 | Vtest = 3 mV (stable), Kepco = 230V, pulses on BatViewer look OK. Tower = 55.8 mK |
| 1530 | Vtest = 3 mV (stable), Kepco = 250V, pulses on BatViewer look OK. |
| 1545 | Vtest = 3.5 mV (stable), Kepco = 290V, pulses on BatViewer look OK. |
| 1605 | Vtest = 4.3 mV (stable), Kepco = 330V, pulses on BatViewer look OK. |
| 1630 | Data taking has stopped, voltage is ramping down. It produced 95 dumps, so the sequence is a little laggy, should have been 88 minutes. |
| 1635 | Fill LN2 cold trap bath |
| 1644 | Flash occurs, Tower peaks to 59.4 mK before falling |
| This is way too low. Something must be configured wrong in the flashing part of the sequence. oh - the problem was that I set it to flash from DCRC4, but the LEDs are connected to DCRC1. |
|
| 1645 | Just checked the kepco meter using the multimeter, reads 0.262 V, but is very unstable, kepco analog meter also bounces around near 0 V, even after removing the multimeter. It seems like the instability is somehow coming from the kepco source itself and that might be causing the instabilities in vtest which reads vtest = -0.293 mV, though again it's unstable, moving between -2 ↔ + 8 mV. Just following the kepco and Keithley for some time, the instabilities in the Keithley vtest readings seem to correspond with the analog meter on the kepco also bouncing around a bit. I wonder what's causing the variations… |
| 1712 | Sequence finished just recently, kepco source is still powered on and unstable near zero. Tower cools to 56.4 mK. |