2020/08/12 (Wednesday)
- Lab in-person: Matt
- Virtual partner: Zach
| 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). |
|---|---|
| Here's the table I made for setting QET bias, with temperature ranges. |
| QET bias table | ||||
|---|---|---|---|---|
| Temperature range | ||||
| 51 to at least 54 | 55.7 | ? | 56 to at least 58 | |
| DCRC4pB | 320 | 310 | 300 | 290 |
| DCRC4pC | 370 | 360 | 350 | 340 |
| DCRC1pB | 360 | 360 | 350 | 350 |
| DCRC1pC | 420 | 410 | 400 | 390 |
| DCRC1pD | 420 | 410 | 400 | 390 |
| 0740 | MB = 29.7% |
|---|---|
| 0830 | Write sequence for +75V with prebias, drift 30.1 mV/s. HVdrift_pos75V_pre15-2min_30p1mVps_multiloop10_60min.msl |
| 0840 | Start a 60 min series at HV = +75V, drifting 0.0301 V/s, prebias 15% for 2min, CDMS detector: Driver Gains = 1x, DCRC4/1 QET biases = (0,320,370,0)/(0,360,420,420) 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 |
| 0840 | Tower = 51.6 mK |
| 0841 | Vtest = 3.2 mV shortly after drift begins. Drift appears to start at +77.9 V. |
| 0946 | Vtest = 6.2 mV, HV = 185.4 V, drift ends. Lag ratio = 1.10. |
| 0946 | Tower = 51.5 mK. |
 |
| Mostly flat. There's a hint of increase - compared to how flat the not-prebiased one was, maybe this hints toward lower charge leakage with prebiasing |
| Gain is significantly lower here than the not-prebiased version. Temperature this time was a couple mK lower. |
| 1050 | Matt enters lab |
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| 1055 | Tower/MC/Coldplate = 52.4/34.7/185 mK, Still = 1.36 K / 0.12 mbar / 0 mW, G1/G2= 395/358 mbar, 1K Pot = 1.64 K / 26±2 mbar. |
| Coldplate and Still are unusually cool. In the past these two left-cable thermometers sometimes shifted between two modes for some reason, maybe that's happening again. | |
| 1100 | Matt Fritts body temperature 98.2 F |
| 1124 | Begin LHe transfer @ MB = 22.2% |
| 1140 | Fill LN2 cold trap bath |
| 1156 | End LHe transfer @ MB = 95.9% |
| 1250 | Matt leaves lab |
| 1650 | Tower = 58.3 mK |
| 1655 | Perform IbIs on DCRC2pD at 58.3 mK. Previously I tried to figure out how much to shift the QET bias to get to the same point on the transition, so that it had about the same IbIs slope. But that does not match dP/dI. That would match the prefactor, but dP/dI is prefactor*QETbias. So, do another analysis to see what QET bias setting would give the same dP/dI at 58 mK as at the lower ~52 mK at which the earlier IbIs was taken. I find that with this channel, the new QET bias should be 400 uA, 20 less than the 420 standard for 52 mK. Previously we were setting the high-temp QET biases 30 lower for the high temps - lets change to 20 lower. |
| QET bias table | |||
|---|---|---|---|
| Temperature range | |||
| 51 to at least 54 | 54 to ? | ? to 58 | |
| DCRC4pB | 320 | 310 | 300 |
| DCRC4pC | 370 | 360 | 350 |
| DCRC1pB | 360 | 360 | 350 |
| DCRC1pC | 420 | 410 | 400 |
| DCRC1pD | 420 | 410 | 400 |
| 1710 | Tower = 58.2 mK. Set QET biases to Column 3 values. |
|---|---|
| Let's try -50V data. Judging from the trends so far, we should try a nominal drift rate of 40.6 mV/s | |
| I modified the drift_w_prebias sheet in the Excel spreadsheet I'm using to generate sequences. Now we can use 0% for prebias and set a non-zero delay. This way it will wait for a time after the rampup for the noise to subside, then it will start drifting and taking data. The start HV value is modified according to the wait time to compensate for the buildup of counterbias. | |
| 1725 | Write new sequence for -50V drifted at 40.6 mV/s, 1min pause after rampup. HVdrift_neg50V_1min_40p6mVps_multiloop10_60min.msl |
| 1731 | Start a 60 min series at HV = -50V, drifting 0.0406 V/s, 1min pause after rampup, CDMS detector: Driver Gains = 1x, DCRC4/1 QET biases = (0,300,350,0)/(0,350,400,400) 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_neg50V_1min_40p6mVps_multiloop10_60min.msl |
| 1730 | Tower = 58.0 mK |
| 1732 | Vtest = -2.7 mV shortly after drift begins. Drift appears to start at -51.9 V. |
| 1837 | Vtest = -10.0 mV, HV = -197.4 V, drift ends. Lag ratio = 1.10. |
| 1840 | Tower = 57.8 mK. |
 |
| 2000 | Matt Fritts body temperature 97.0 F |
|---|---|
| 2200 | Estimate that for -75V we will want 51.8 mV/s. Write sequence for this with 1min pause after rampup. HVdrift_neg75V_1min_51p8mVps_multiloop10_60min.msl |
| note that max bias is 264.4 V, not sure whether the meter reads that high. | |
| 2208 | Start a 60 min series at HV = -75V, drifting 0.0518 V/s, 1min pause after rampup, CDMS detector: Driver Gains = 1x, DCRC4/1 QET biases = (0,300,350,0)/(0,350,400,400) 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_neg75V_1min_51p8mVps_multiloop10_60min.msl |
| 2205 | Tower = 57.0 mK |
| 2209 | Vtest = -4.5 mV shortly after drift begins. Drift appears to start at -77.4 V. |
| 2314 | Vtest = -14.0 mV, HV = -262.8 V, drift ends. Lag ratio = 1.10. |
| 2314 | Tower = 56.6 mK. |
 |
| Drift is too fast, should try 48.7 mV/s |
| Note that - and + gains look similar. Not yet seeing the much-lower gain at -bias… |