2020/03/02 (Monday)
| 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 falling at mK/hr, mK/day | |
| 0900 | Tower/MC/Coldplate = 53.2/35.7/181 mK, Still = 1.27 K / 0.120 mbar / 0 mW, G1/G2= 413/385 mbar, 1K Pot = 2.12 K / 26 mbar. MB = 66.6% |
| 0905 | Fill LN2 cold trap bath |
| 1020 | Tower temperature increased after LN2 fill, from 53 mK to 64 mK. Why? I guess maybe because the still got a little colder and we have less cooling power. Let's try heating the still. |
| 1025 | Set Still Heater to 5.0 mW. Still and Circulation pressures increase, Tower temperature falls. |
| 1030 | Start assembling lead/poly shield It's been kind of hard to see Am peaks in the data, but in Run 70 and previous it got a lot easier with the shield in place, reducing the background. |
| 1135 | Tower = 54.7 mK, Still = 0.190 mbar / 5 mW, G1/G2= 492/462 mbar, 1K Pot = 2.18 K / 24 mbar. |
| 1140 | East and West shield walls in place. North and South frames for lead attached. (Skipping N/S poly.) |
| 1430 | North and South lead in place, lead in all 4 walls (5 1/8-inch layers) |
| In Run 70 when the shield was erected (3 walls) we drifted HV at 2.64 V/min = 44 mV/s. But that's only a little lower than what we did this run without the shield. In Run 70 without the shield we drifted at 65 mV/s. If we assume the shield reduces the rate by the same ratio as Run 70 then we should try 31 mV/s now. | |
| 1440 | Use HVscan.py to generate a sequence HVdrift_250V_31mVps_pre10-2_80min.msl. This should bias detector to 250 V after a 2 minute 10% prebias, then drift by 31 mV/s and run for 80 minutes (ending at about 400V). Then flashes 30 seconds and waits 30 minutes. |
| 1451 | Start a series at HV = 250→400V, rate 31mV/s, 80 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 and 5Hz in-run randoms, trigger on DCRC1pD threshold = 9 Use sequence HVdrift_250V_31mVps_pre10-2_80min.msl |
| 1503 | Data starts |
| 1505 | Vtest = 3.1 mV, Kepco = 235 V, pulses on BatViewer look OK. (Kepco dial reading is lower than what the Fluke meter reads.) Tower = 53.4 mK |
| 1520 | Vtest = 3.3 mV, Kepco = 250 V, pulses on BatViewer look OK. |
| 1555 | Vtest = 4.1 mV, Kepco = 305 V, pulses on BatViewer look OK. Tower = 53.1 mK |
| series produced 86 dumps | |
| 1745 | Fill LN2 cold trap bath |