2020/03/04 (Wednesday)
| 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. Lead/poly shield erected (4 lead walls, 2 poly walls). |
|---|---|
| Overnight: After flash Tower was down to 54.0 mK by 10:30pm, then fell steadily to 52.0 mK at about 5:10am, then rose a bit before starting to fall again - we've seen this little rise on multiple mornings recently. Rose to about 52.7 mK then began falling at the same rate. Maybe these morning rises are caused by increased bath pressure due to activities in the helium liquification/recovery system. | |
| 0940 | Tower/MC/Coldplate = 51.6/33.8/191 mK, Still = 1.50±0.05 K / 0.190 mbar / 5 mW, G1/G2= 510/471 mbar, 1K Pot = 2.19 K / 26 mbar. MB = 67.9% |
| 0950 | Fill LN2 cold trap bath |
| 1010 | As has happened in the last few days, Tower temperature has increased since the LN2 transfer, 51.5→54.5 mK. This time I watched the Still temperature, but there's no clear change. As usual the only other obvious effect is a temporary dip in Circulation pressures. |
| Use HVscan.py to generate a sequence HVdrift_300V_31mVps_pre10-2_75min.msl. This should bias detector to 300 V after a 2 minute 10% prebias, then drift by 31 mV/s and run for 75 minutes (ending at about 440V). Then flashes 30 seconds and waits 30 minutes. | |
| Use HVscan.py to generate a sequence HVdrift_150V_31mVps_pre10-2_120min.msl. This should bias detector to 150 V after a 2 minute 10% prebias, then drift by 31 mV/s and run for 120 minutes (ending at about 373V). Then flashes 30 seconds and waits 30 minutes. | |
| 1015 | Check HV with multimeter: 0.36 V. Short the banana leads to the HV box together to ground the detector. We'll take some 0-Volt data. |
| 1019 | Start a series at HV = 0V, 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 No sequence, just hit Start button. |
| 1030 | Abort series, two channels are railed. Probably happened after I shorted out the HV. Let's fix these. |
| 1033 | Start a series at HV = 0V, 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 No sequence, just hit Start button. |
| 1045 | Tower = 55.7 mK. Pulses look OK on BatViewer. |
| At Dump 35, DCRC1pB railed. Then by Dump 36 it was back with a much higher baseline, but probably OK. | |
| 1154 | Stop data series. 79 dumps. |
| 1245 | Perform IbIs on all channels at 0V bias. This is specifically to calculate dP/dI (calculated balancing factors). For each channel record Vout for 6 different QET bias settings: 900, 800, 700 uA (this should be in the normal state and is used to calculate the V offset), and the current QET bias setting, and 5 above and below the current QET bias setting (this to give dV/dI at the transition setting). From Eqn 24 in my dP/dI note this will give the “prefactor” for the dP/dI calculation. Multiplying that by the QET bias gives relative dP/dI (for absolute dP/dI you need a bunch of conversion factors and the shunt resistance). These dP/dI factors are the calculated balancing factors, i.e. the conversion from pulse height to keV. |
| DCRC chan | Det chan | dP/dI from IbIs (rel to F) | dP/dI from data (rel to F) |
|---|---|---|---|
| DCRC4pB | pB | 2.72 | 3 |
| DCRC4pC | pD | 1.9 | 2 |
| DCRC1pB | pA | n/a | 1 |
| DCRC1pC | pC | 0.89 | 3 |
| DCRC1pD | pF | 1 | 1 |
- DCRC1pB has the issue seen before (and attributed to the SQUID) that in IbIs at high QET biases, Vout is flat rather than sloping downward as it should for normal state resistance. In the past I was able to estimate the offset but I haven't attempted that here.
- Balancing factors (dP/dI) from this IbIs agree with empirical ones from data except for DCRC1pC (side1pC).
| 1305 | Start a series at HV = 300→440V, rate 31mV/s, 75 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_300V_31mVps_pre10-2_75min.msl |
|---|---|
| 1321 | Data starts |
| 1325 | Vtest = 4.0 mV, Kepco = 285 V, pulses on BatViewer look OK. |
| 1345 | Oops - I left BOR Randoms set at 10,000, 5Hz. So as of Dump 24 it's still randoms, no triggered pulses. Fixed that. |
| 1345 | Vtest = 4.4 mV, Kepco = 305 V, pulses on BatViewer look OK (except that they are all randoms) |
| As of Dump 35, we are finally seeing triggered data. Hard to say whether this will be a usable series. There will only be 40 or so dumps with triggered data (which isn't too bad), but another problem is that the first dump will have only about 300 randoms instead of the usual 1000, so maybe the noise processing won't work well. | |
| 1405 | Tower = 54.2 mK |
| 1420 | Vtest = 5.2 mV, Kepco = 360 V, pulses on BatViewer look OK. |
| 1440 | Vtest = 5.7 mV, Kepco = 405 V, pulses on BatViewer look OK. |
| Series ended with 82 dumps | |
| 1459 | LED flash. |
| 1625 | Tower = 54.3 mK, close to pre-flash |
| 1625 | Start a series at HV = 150→373V, rate 31mV/s, 120 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_150V_31mVps_pre10-2_120min.msl |
| 1633 | Data starts. Vtest = 1.6 mV, Kepco = 145 V, pulses on BatViewer look OK. |
| 1700 | Fill LN2 cold trap bath |
| 1700 | Vtest = 2.0 mV, Kepco = 180 V, pulses on BatViewer look OK. Tower = 53.8 mK |
| 1725 | Vtest = 2.5 mV, Kepco = 215 V, pulses on BatViewer look OK. Tower = 56.1 mK, rising since the LN2 fill. |
| 129 dumps in the series |
Note: the change in temperature during this series definitely showed up as a time dependence in the calibration lines. The increase from 54.0→56.4 mK after the LN2 fill resulted in a 7% fall in the peak position.