2019/03/25 (Monday)
| Setup | DIB1/3/4 → 3.2 MHz filters 2/3/1 → cable 3/1/2 → gender changer 3/?/2 → HVConn 1/3/2 → HV 1/2 → DCRCX(4)/DCRC50(3) DCRC33(2) → 1kV power supply → HV input Lead poly shield is erected, N/E/W walls complete, no poly or lead on S wall. PuBe source present in paraffin barrel behind lead stack. |
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| 0910 | Tower/MC/Coldplate = 43.4/31.5/200 mK, Still = 1.85±0.15 K / 0.160 mbar, G1/G2 = 267/236 mbar, 1K Pot = 1.79 K / 15 mbar. MB = 67.3% |
| 0930 | Fill LN2 cold trap bath |
| 0930 | Start purging Ebox with N2 from the Vent port of the LN2 Dewar. |
| 0940 | Check channels, all look OK. Adjust driver offsets. |
| 0946 | Start 2 PuBe series at HV = 300→400V @ 5.4 V/min (18 min duration) with 1 minute 15% prebias CDMS detector: Driver Gains = 1x, DCRC4/3 QET biases = (410/370/430)/(430/390/420) uA, Front-End Gains = (4/2/3)/(10/15/10) 1000 BOR randoms, trigger on DCRC3pB/D threshold = 7/7 use sequence HVdrift_fast_2X300V_5p4VPM_prebias_15_1_dur_18min.msl |
| 0950 | During HV rampup Vtest peaks at about 142 mV, then falls a little. |
| 0953 | But during the prebias it goes up to about 170 mV |
| 0954 | Data has started, channels look OK. |
| 0955 | HV = 306.2 V, Vtest = 84 mV. |
| 0958 | HV = 322.3 V, Vtest = 122 mV. Leakage is pretty high. |
| 0958 | HV = 336.7 V, Vtest = 167 mV. Leakage is pretty high. |
| 1004 | HV = 352.8 V, Vtest = 185 mV. Leakage is pretty high. |
| 1008 | HV = 372.7 V, Vtest = 220 mV. Leakage is pretty high. |
| 1011 | HV = 388.9 V, Vtest = 175 mV. Leakage is now, suddenly, falling. Why? |
| 1012 | HV = 394.3 V, Vtest = 120 mV. Leakage leveling out. |
| 1030 | Check channels during pause after flash, all look OK |
| 1130 | The second series is finished. Leakage was a lot lower. Started at about 50 mV, ended at around 160 mV. It did not increase linearly: about halfway through it was only up to about 68 mV. At around 3/4 through it reached 100 mV and then increased more rapidly. |
| 1135 | It looks like DCRC4 PA railed at some point during or after the sequence. |
| 1235 | Remove PuBe source from lab and return to Kevin Booth and Kurt Wick in Tate Lab. |
| 1255 | Check the channels, all look OK. |
| Not sure what the HV drift rate should be for taking data with no external source and the shield erected. Event rate is about 1/2, so let's try halving it, for a nominal rate of 2.7 V/min. Generate sequence to do a single series from 300 to 400 V with 2.7 V/min drift, so 37 min series. | |
| 1307 | Start a background series at HV = 300→400V @ 2.7 V/min (37 min duration) with 1 minute 15% prebias CDMS detector: Driver Gains = 1x, DCRC4/3 QET biases = (410/370/430)/(430/390/420) uA, Front-End Gains = (4/2/3)/(10/15/10) 1000 BOR randoms, trigger on DCRC3pB/D threshold = 7/7 use sequence HVdrift_fast_300V_2p7VPM_prebias_15_1_dur_37min.msl |
| 1311 | Vtest seems to be peaking at around 140 mV during rampup, about the same as the last two times. |
| 1317 | HV = 305.3 V, Vtest = 56 mV. Data has started. Check channels, all look OK. |
| 1321 | HV = 315.2 V, Vtest = 66 mV. |
| 1326 | HV = 327.6 V, Vtest = 92 mV. Leakage is accelerating. |
| 1331 | HV = 340.2 V, Vtest = 102 mV. Leakage is oscillating a little. |
| 1347 | HV = 381.7 V, Vtest = 154 mV. Leakage is worst than the last time, but not as bad as before we started purging. |
| 1350 | HV = 389.8 V, Vtest = 185 mV. |
| 1354 | HV = 398.7 V, Vtest = 190 mV. Data stopped, HV ramping down. |
| 1440 | Walked away for a bit - MIDAS has crashed and I guess it happened in the middle of the flash, because temperature is high (57 mK) and flat. |
| 1445 | Kill and restart MIDAS. Sequence finishes. Tower immediately starts cooling. |
| Looking at the last data series, it looks like the HV drift rate was not high enough to cancel the counterbias. Instead of 2.7 V/min it should probably be 3.9 V/min (0.065 V/s). | |
| Make a new sequence to drift 3.9 V/min. But modify what the Python script produces to use LOOP and ODBINC, to decrease the number of lines in the sequence. I'm hoping that this will be more stable. (And hopefully I did it right - we'll try it.) | |
| 1545 | Tower = 43.3 mK and flat. Check channels: all look OK. |
| 1550 | Notice that the LN2 vent is frosty. I increased the flow rate to the Ebox purge to try to reduce the leakage. |
| 1553 | Start a background series at HV = 300→400V @ CDMS detector: Driver Gains = 1x, DCRC4/3 QET biases = (410/370/430)/(430/390/420) uA, Front-End Gains = (4/2/3)/(10/15/10) 1000 BOR randoms, trigger on DCRC3pB/D threshold = 7/7 use sequence looptest_HVdrift_fast_300V_3p9VPM_prebias_15_1_dur_26min.msl |
| VTest peaks around 132 mV during rampup, a little better than before. | |
| 1559 | Prebias loop finished, HV = 342.4 V |
| 1602 | HV = 301.3 V, Vtest = 42 mV. |
| 1604 | HV = 305.1 V, Vtest = 45 mV. |
| 1607 | MIDAS crashed. crap. HV = 307.2 V, Vtest = 43 mV. HV is not changing, of course. |
| 1610 | Restart MIDAS. The only program that wasn't running was mhttpd. This time I decided to just do ./start_daq_umn.sh without killing anything. mhttp started up again, and the sequence started where it left off. |
| 1612 | HV = 312.5 V, Vtest = 47 mV. |
| I made a mistake in the sequence: I forgot to update the increment during the drift. We'll abort this sequence and fix that. | |
| 1615 | abort sequence |
| 1622 | Dialled HV down to 0 V by changed DCRC2 QI bias by 0.1 until 11.56. |
| 1626 | Start a background series at HV = 300→400V @ 3.9 V/min (26 min duration) with 1 minute 15% prebias CDMS detector: Driver Gains = 1x, DCRC4/3 QET biases = (410/370/430)/(430/390/420) uA, Front-End Gains = (4/2/3)/(10/15/10) 1000 BOR randoms, trigger on DCRC3pB/D threshold = 7/7 use sequence looptest_HVdrift_fast_300V_3p9VPM_prebias_15_1_dur_26min.msl |
| 1635 | HV = 302.8 V, Vtest = 41 mV. Data has started. Channels look OK. |
| 1638 | HV = 313.1 V, Vtest = 48 mV. |
| 1640 | MIDAS has crashed again. Restart MIDAS without killing anything. Starts up again where it left off. Here's a log of messages when the crash occurred: MIDASlog. First sign of trouble was: |
16:38:23.362 2019/03/25 [mserver,INFO] Client 'mhttpd' on buffer 'SYSMSG' removed by cm_watchdog (idle 10.1s,TO 10s)
| 1645 | HV = 334.6 V, Vtest = 73 mV. |
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| 1649 | HV = 349.0 V, Vtest = 90 mV. |
| 1652 | HV = 360.3 V, Vtest = 123 mV. |
| 1655 | HV = 370.5 V, Vtest = 137 mV. |
| 1658 | HV = 381.9 V, Vtest = 153 mV. |
| 1701 | HV = 393.2 V, Vtest = 170 mV. |
| 1705 | Fill LN2 cold trap bath |
| 1705 | MB = 56.1% |
| 1710 | Stop purging the Ebox with N2 for now. We'll investigate the leakage some more tomorrow. |
| 1715 | The flash has happened and the sequence is continuing. made it to the end without crashing. |