2019/11/25 (Monday)
| Setup | DIB1/2/4 → 3.2 MHz filters → cable 1/2/3 → gender changer 1/2/3 → movable source controller/board with external Feedback resistor/nothing → DCRC55(1)/DCRC33(2)/DCRC50(3) |
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| Overnight | Ran a script that moved the source a few steps every few min. We started at y=-24.3 mm; this script should push us out to y=-38.5 mm and end at 07:01. |
| 0357 | Temperature pattern from the move sequence changed somewhat, the highest peak in the 12-move cycle is now a little lower. Don't know whether that means anything. (If I miscalculated we may have hit the endstop - but that should still be 3mm away.) |
| 0642 | MB = 20.4% |
| 0705 | Move sequence is finished. Tower = 70 mK. Do a hot Al flash for 90s using the sequence Al_flash.msl. Tower peaks at 1.7 K. |
| 0830 | Tower/MC/Coldplate = 35.2/30.3/193 mK, Still = 1.51 K/ 0.120 mbar / 0 mW, G1/G2= 252/250 mbar, 1K Pot = 1.62 K / 20±1 mbar. MB = 17.8% |
| 0830 | Turn off motor power supply, power down arduino. Check that Keithley meter is not connected to breakout box. |
| 0835 | Fill LN2 cold trap bath. |
| 0835 | Check resistances of both endstops, both appear to be open. |
| 0835 | Tower = 34.8 mK and cooling. Check the channels - they all look good! |
| 0840 | Tower = 34.4 mK |
| 0840 | Start 1x S1/S2=-4/+4,+4/-4 V loop of 30 min Bkg data series, Driver gain = 1, with 1000 initial randoms, with 30s flashes and 30 min cooldowns trigger on DCRC2pA/B/C = 8/8/8 ADC using sequence qbias_mp4_pm4_loop.msl |
| 0840 | IVC = 74 ubar. Note that we have not been pumping on the IVC. |
| 0900 | Tower = 33.4 mK and flat |
| 1020 | Second data series is finished. Took a look at the last data series - it looks consistent (although ydelay is getting less sensitive as we move over the middle of Side2 pB). |
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| It will take 3 hours to move to the -y endstop. We may as well do it. The question is whether we can do that and also take more data, before beginning the warmup. Could start the data at 3pm probably. | |
| 1025 | Power arduino and connect to it via telnet. Arduino responds to two “marco”s with “polo”. Turn on motor power supply, which is set to 6.4 V. In telnet session set dwell to 40 ms. Scope is on. |
| 1025 | Edit stepper_loop.py, change “nrepeat” from 215 to 45. |
| 1028 | Move 45x-4 steps with 4 min wait in between using stepper_loop.py. Pipe this output to /home/mast/cdms/arduino/stepper_loop.out. This should push us out to y=-41.52 mm. That's just 0.15 mm short of the endstop - so we should keep an eye on the endstop resistance as we get close. It will end at 13:28. |
| 1035 | Monitoring endstop1-to-chassis resistance with Keithley meter. Endstop2 > 10 GΩ. The reading is drifting upward, from around 5 GΩ to 50 GΩ and climbing. It doesn't seem to be adding excess heat to the fridge. |
| 1200 | Endstop1 resistance now reads “O.L” on the Keithley. |
| 1315 | Endstop1 resistance has dropped to 20.6 Ω. Not sure how to stop the python script, so instead just turn off motor power supply, then unplug arduino. |
| Looks like it hit at the 1:13:13 move, and I stopped the arduino right after this move. So we stopped after move 42. According to the calculation that should put us at -41.32 mm. In the clean room we measured the endstop at -41.67 mm. So looks like we were off by 0.35 mm. |
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| Pobell has copper/brass linear expansion coefficients of around -0.00325/-0.0042. The copper base plate will contract less than the brass threaded rod. At around 55 mm, the brass contracts 0.23 mm, the copper 0.18 mm, for a difference of 0.05 mm. This would tend to make the endstop farther away, not closer as observed. | |
| 1327 | Tower = 54 mK. Do a hot Al flash for 90s using the sequence Al_flash.msl. Tower peaks at 1.7 K. |
| 1355 | MB = 9.8%, getting low. 1K Pot temperature and pressure fell slightly at around 13:40, not sure if that's an indication that the fridge will start failing soon |
| 1410 | Tower = 40 mK. Check phonon channels - some look crappy. Zap all phonon channels |
| 1419 | Channels look fine now - adjust the driver offsets for channels on DCRC1 and DCRC3 to be closer to -0.9 |
| 1442 | Start 1x S1/S2=-4/+4,+4/-4 V loop of 30 min Bkg data series, Driver gain = 1, with 1000 initial randoms, with 30s flashes and 30 min cooldowns trigger on DCRC2pA/B/C = 8/8/8 ADC using sequence qbias_mp4_pm4_loop.msl |
| 1505 | Power interruption - pumps stopped, fridge got hot: tower → 150 mK. |
| 1515 | Pumps are started again |
| 1545 | Got about 18 minutes of data before the power outage. OK, let's begin warmup. |
| 1550 | MB = 7.1%. Recovery meter = 327812 cuft. |
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| 1K Pot did not recover after power outage. It's around 3.7 K. Also all the valves closed automatically. Now open the circulation path through G2. G1/G2 highish, 440 mbar. Tower 94 mK and rising. | |
| 1550 | Stop circulation: close V6. Allows mix to expand into still line |
| 1555 | Stop 1K Pot: Close 1K Pot speedivalve to stop pumping on pot. Leaving needle valve open. Notice that V4a is closed - that's why the 1K Pot wasn't working. Open V4a to pump out line to the speedivalve. |
| 1600 | Close valve to 4He pump. Open 4He outlet to “exhaust” and close recovery valve. Turn off 4He pump. |
| 1603 | Recovery meter = 327817 cuft. |
| 1610 | Let 2.2 mbar He gas into vacuum manifold. Then open cryostat vacuum jacket valve to let this into the vacuum jacket. Vaccum Jacket → 0.012 mbar. |
| 1611 | Recovery meter begins to speed up. |
| Start pumping mixture to dump, close off 13B (the trap we were circulating though), close V1. Open V3 and V9. Open V6 → 24.3. | |
| 1615 | Recovery = 1 cuft / 14.2 seconds |
| 1620 | Stop pumping out LN2 Trap 2. Open both sides of fridge to G1. Fridge = 104 mbar. Tower = 1.3 K. |
| 1624 | MB = 2.6% |
| 1633 | Let 2.5 mbar He gas into pumping station manifold, then let this into the IVC. IVC → 4.6 ubar. |
| 1633 | Recovery = 327900 cuft |
| 1634 | Restart DAQ programs. |
| Tower climbs to 3.6 K | |
| 1636 | Restart programs and MIDAS. Sequence starts where it left off. Kill sequence. |
| 1637 | Fridge Pressure G1 is climbing G1 → 360 mbar. |
| 1647 | Fridge(G1) = 840 mbar and rising. Let's start pumping fridge to dump. Open V6 to 13.0%. |
| 1650 | Switch thermometer to MC(Cernox) |
| 1650 | MC(Cernox) = 4.2 K. It's not falling, so probably we'll be able to pump all the mix to dump. |
| 1655 | Fridge(G1)/Dump(G2) = 125/580 mbar. Both are rising. Let's open V6 further, to 13.5% |
| 1700 | P1(fridge) falls into range. Open V6 all the way, 100%. |
| 1700 | Fridge(P1)/Dump(G2) = 1.1/729.7 mbar. |
| 1705 | Fridge(P1)/Dump(G2) = 0.22/730.0 mbar. |
| Barometric pressure = 29.54“ (source is https://w1.weather.gov/data/obhistory/KMSP.html.) G2 = 730.6 mbar. Corrected dump pressure = 717.7 mbar. Around 3 mbar less than Run 70. |
Ptrue[mbar] = Pdisplay[mbar] + ( Pbar[inHg] - 29.92 ) * 33.86
| 1715 | Fridge(P1)/Dump(G2) = 0.050/730.4 mbar. MC(Cernox) = 4.6 K, rising slowly. |
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| 1715 | Stop pumping mix to dump. Isolate fridge, close all IVC valves, turn off 3He pump. |