2020/09/03 (Thursday)
- Lab in-person: Matt
- Virtual partner: Michael
| Setup | Run 73. DIB 1/3/4 → Stripline 43/48/41 → pi-filters 1/2/3 → Cable 3/1/2 → nothing/nothing/accessory_interposer → HV_Conn 1/3/2 → HV 1/2 → DCRCX(4)/DCRC55(1)-master; DCRC33(2) → HV control. DCRCs on overnight. Lead/poly shield erected (4 lead walls, 2 poly walls). |
|---|---|
| 0850 | MB = 30.0% |
| 1210 | Matt Fritts body temp = 97.0 F |
| 1211 | Start a 60 min series at HV = 0V CDMS detector: Driver Gains = 1x, DCRC4/1 QET biases = (0,320,370,0)/(0,360,420,410)uA, Front-End Gains = (3/3/3)/(5/5/5) 1000 BOR & 5 Hz in-run randoms, trigger on DCRC1pD threshold = 8 Use sequence SimpleDataLoopNoFlash.msl |
| 1211 | Tower = 50.3 mK |
| Time | MB% |
|---|---|
| 09:50 | 28.4 |
| 10:50 | 26.7 |
| 11:50 | 24.6 |
| 12:50 | 22.7 |
| 1310 | Matt enters lab |
|---|---|
| 1310 | Tower/MC/Coldplate = 50.4/31.8/189 mK, Still = 1.39 K / 0.095 mbar / 0 mW, G1/G2= 274/259 mbar, 1K Pot = 1.70 K / 50±2 mbar. |
| 1335 | Begin LHe transfer @ MB = 21.3% |
| 1408 | End LHe transfer @ MB = 93.3% |
| 1410 | Fill LN2 cold trap bath |
| 1422 | Tower temperature peaks at 87 mK then starts cooling |
| 1430 | MB = 92.2% |
The table below is a copy from a few days ago, showing how the Main Bath started boiling off faster after the partial warmup, and how we restored it somewhat by pumping out the Cryostat Vacuum Jacket some more:
| 80%-20% boiloff time [hours] | |
|---|---|
| early Run 73 | 40.3 |
| after partial warmup | 34.1 |
| after pumping CVJ 2 days | 37.1 |
Before the boiloff period that ended today we pumped on the CVJ more, for 1 day. Looking at the boiloff rate shows not much improvement; 80%-20% boiloff time for this period is 37.3 hours.
| 2032 | Start a 60 min series at HV = -50V, drifting 0.0301 V/s, 1min pause after rampup, CDMS detector: Driver Gains = 1x, DCRC4/1 QET biases = (0,320,370,0)/(0,360,420,410)uA, Front-End Gains = (3/3/3)/(5/5/5) 1000 BOR & 5 Hz in-run randoms, trigger on DCRC1pD threshold = 8 Use sequence HVdrift_pos75V_pre15-2min_30p1mVps_multiloop10_60min.msl |
|---|---|
| 2032 | Tower = 50.4 mK |
| 2032 | Vtest = -1.9 mV shortly after drift begins. Drift begins at -51.8 V. 1.5% HV loss. |
| 2138 | Drift ends at HV = -197.3 V. Vtest = -6.3 mV, 1.3% HV loss. Lag Ratio ~ 1.10. |
| 2138 | Tower = 50.8 mK |
| later look at data shows Lag Ratio = 1.09 |
 |
| I took this -50V series to double check the Luke gain, which is relatively high at neg bias below around 100V. I wondered whether that was due to temperature/QET bias changes. Looks like it's just as high now. |