2017/11/17 (Friday)
| Setup: DIB1/3/4 → SL 27/19/20 → 3.2 MHz filters → cables 2,1,3 → HV board inputs 1,3,2 → HV board outputs 1,2 → DCRC55(1)/50(3). DCRCs not powered. | |
| 0905 | Tower/MC/Coldplate = 33.8/28.0/154 mK, Still = 1.24 K / 0.110 mbar, G1/G2 = 120/125 mbar, 1K Pot = 1.70 K / 110±20 mbar, MB = 32.8% |
| Overnight, as Tower was cooling, there were some oscillations in Tower temperature and Condenser pressure for a few hours. Those went away, then Tower cooled steadily and Condenser pressure rose steadily, overnight from about 90 to about 120 mbar. Tower seems to still be cooling to base by about 0.15 mK/hour. Pressure would rise for ~40 minutes while temperature falling - then pressure would suddenly fall, and temperature would suddenly rise. Then it would repeat, with overall cooling and increasing pressure. At least 6 cycles of this. |
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| 0910 | Fill LN2 cold trap bath. |
| 0935 | Set ODB settings on DCRC1&3 to mostly standards. Turn off 15V Power, since we have some unconnected charge channels. Power on DCRCs and turn on DCRCdriver program. Small tower spike, Δ = 1 mK, then comes right back down (probably after starting DCRCdriver, which turns off the 15V Power). |
| 0940 | Set all SQUID biases to -80 and all Lockpoints to -4 |
| 1005 | Playing with QET biases on DCRC3pB. Superconducting from 0 to 475 uA. At 500 uA, first pulses! Also oscillations. Increasing to 530 uA seems to get past the oscillations, ~ 5 kHz. |
| 1025 | Took a quick IbIs curve on this channel, which is Side1pA. In the normal region, dVout/dIbias = -0.001102 V/uA. The driver gain is set to 1. With the built-in gain of 2, loop gain 10.5, Rfeedback 1233 Ω, we get dIb/dIs of 23.5. This implies Rtes/Rshunt is 22.5. Looking at the Run 61 summary, Side1pA had a measured Rn around 112 mΩ. This implies that Rshunt is now around 5.0 mΩ. |
| 1030 | Zap SQUIDs on DCRCs 1&3 using the DCRC Control tool. Standard settings: on/off/iterations = 2s / 30s / 2. Tower rises to 43 mK then falls. Still spikes from 0.12 to 0.20 mbar with two peaks visible. |
|---|---|
| 1055 | Install two walls of lead/poly shield, on West and East side. |
| 1101 | Start LHe transfer (MB = 29.6%) |
| 1200 | End LHe transfer (MB = 89.4%) |
| 1230 | Finish SQUID tuning on DCRC1 pA/B/C. |
| 1245 | Finish SQUID tuning on DCRC3 pB/C/D. |
quick SQUID Tuning notes:
- Trigger on Test Signal
- Connect Test Signal to feedback, 400 Hz, maybe 100 mVpp
- Set Polarity to OPEN and ADCsource to PREAMP
- Start with QET bias = 0, Lockpoint = 0, SQUID bias = 0
- Increase SQUID bias (negative for RevC.1, positive for RevC) to maximized modulation depth (Vpp) while avoiding cusps
- Increase Lockpoint (negative for RevC.1, positive for RevC) so that x-axis intersects at point with high slope
- then set back to normal: disconnect test signal, set ADCsource to FEEDBACK, set Polarity to NON-INVERTING
| DCRC | Detector | DIB | SQUET | SQUID bias | Lockpoint |
|---|---|---|---|---|---|
| DCRC1pA | Side1pE | DIB1pA | ZC-68pA | -78 | -3 |
| DCRC1pB | Side1pB | DIB1pB | ZC-68pB | -68 | -3 |
| DCRC1pC | Side1pD | DIB1pC | ZC-68pC | -100 | -4.5 |
| DCRC3pB | Side1pA | DIB3pC | ZC-74pC | -90 | -5 |
| DCRC3pC | Side1pC | DIB4pC | ZC-31pC | -70 | -3 |
| DCRC3pD | Side1pF | DIB4pD | ZC-31pD | -60 | -2.5 |
| 1325 | Get all DCRC1 channels into transition, seeing pulses: QET biases are DCRC1 pA/B/C = 500/490/520 uA. However very strong 15 kHz oscillations in pB, can't seem to avoid them by adjusting QET bias. |
|---|---|
| 1355 | Get all DCRC3 channels into transition, seeing pulses: QET biases are DCRC1 pB/C/D = 490/430/540 uA. |
| 1420 | Tower = 33.2 mK. 1K Pot has fallen a bit since the transfer : 1.65 K / 40 mbar. |
| 1425 | Triggering on DCRC3pD. Found that the timing link between DCRCs wasn't working, because DCRC1 pulses were not showing up at the start time. Turned off MIDAS programs and turned them back on - now the timing link is OK. |
| 1500 | Try applying bias. Watching DCRC1pC. |
| Vbias [V] | Vtest [mV], initial | Vtest [mV] after about 1 minute | Baseline elevation [mV] after about 1 minute |
|---|---|---|---|
| 5 | 8.4 | 1.6 | |
| 10 | 10 | 2.1 | |
| 20 | 4.6 | ||
| 30 | 22 | 5 | 10 |
| 40 | 24 | 6 | |
| 50 | 22 | 7 | 20 |
| 60 | 6 | 28 | |
| 70 | 7 | 37 | |
| 80 | 7.5 | 43 | |
| 90 | 7 | 39 | |
| 60 | 1 | 8 |
note that prebiasing (backing down to 60 from 90) reduced the baseline elevation (parasitic power).
| 1605 | Built a sequence file to do IbIs on DCRC1pA. It will step QET bias from 750 to 400 uA in -0.5 uA steps and take 3 seconds of data at each step. There's also a 3 second wait after resetting the QET bias and a presumed 1 second overhead per step. This adds up to about 82 minutes to complete the sequence. These will be labeled QBscan_DCRC1p0_#### per step in the /livedata directory. I will move these to /byseries/07171117_2500 after the sequence completes. |
|---|---|
| 1610 | Begin IbIs data sequence on DCRC1pA with HV=0V from 750 to 400 uA in -0.5 uA steps, 3 seconds of data per step |
| 1615 | Built IbIs sequences for all 6 channels. They are ready to run (maybe remotely). |
| 1620 | Tower = 33.0 mK, G1/G2 = 139/143 mbar, 1K Pot = 1.66 K / 40 mbar |
| 1625 | Fill LN2 cold trap bath (from bomb Dewar) |
| 1630 | Sequence is progressing more slowly than predicted. Looks like it will take 145 minutes (about 2.5 hours). Overhead per step is apparently close to 6.5 seconds. For all channels, total of 15 hours. This sequence should finish close to 18:35. |
| 1945 | Begin IbIs data sequence on DCRC1pB with HV=0V from 750 to 400 uA in -0.5 uA steps, 3 seconds of data per step |
| sequence should finish at 21:10 | |
| 2105 | Something is wrong with the sequence. It stopped producing files after 554 uA, and the sequencer page just has a stuck progress bar. MIDAS web page not responding to button clicks. |
| 2200 | Restart MIDAS. Restart dcrc driver, tower fe, trigger fe. |
| 2208 | Begin IbIs data sequence on DCRC1pB with HV=0V from 750 to 400 uA in -0.5 uA steps, 3 seconds of data per step |
| This time it completed. Ended at 00:24, so 1 hr 16 min |