2021/09/22 (Wednesday)
- Lab in-personnel: Giulia and Matt
| Status | Run 74 in progress. First cooldown after IVC rebuild. |
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| Tower thermometer is reading high, probably this is a thermometer problem and the actual temperature is much lower. High noise in some of the charge channels. | |
| Setup: DIB1/2+acc → SL 41/43 → 3.2 MHz filters → cables 2/3 → nothing/ |
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| Position of Am source: y = 0.0 mm | |
| Circulation is suspended and 1K Pot needle valve is closed, letting the fridge warm up. Skipped the LHe transfer yesterday, letting the bath boil off. | |
| 0915 | Tower = 1.42 K, warming slowly, about 0.01 K/hr |
| 0915 | Turn on MC heater → 100 uW. Tower warming faster. |
| 1016 | Tower/MC/Coldplate = 1495/1701/2559 mK, Still = 2.03 K / 1000 mbar / 0 mW, G1/G2= 25500/10500 mbar, 1K Pot = 1.56 K / 10±1 mbar. MB = 1.9%. |
| 1023 | Fill LN2 cold trap bath. |
| 1025 | At 10kHz noise in DCRC3qI/qO/DCRC1qI/qO = 1.2/0.9/1.8/1.8 8e-6. This is q3/q1/q4/q2 At 3kHz (peak) noise in DCRC3qI/qO/DCRC1qI/qO = 1.4/1.1/2.7/4.3 e-6. |
| Noise is slightly higher than yesterday. | |
| 1130 | Tower = 1.57 K, warming ~ 0.06 K/hr |
| 1135 | Turn off MC heater, we'll see how flat it gets |
| 1245 | Tower = 1.57 K, cooling very slowly. Pretty much flat after turning off the MC heater |
| 1245 | Turn on MC heater → 400 uW |
| 1330 | Tower reached 1.68 K, however now the temperature is falling. Seems to be caused by 1K Pot temperature and pressure falling, → 1.38 K / 1.8 mbar. Maybe because the bath is now below the siphon, and it's no longer being (slowly) filled. Tower = 1.56 K and falling |
| 1330 | Close 1K Pot speedivalve. So now we are no longer pumping on the 1K Pot. 1K Pot temperature rises immediately, → 1.76 K. Tower = 1.55 K, no longer falling. |
| 1350 | Tower = 1.61 K, warming ~ 0.23 K/hr. 1K Pot = 4.00 K and rising |
| 1355 | Turn up MC heater → 1000 uW |
| 1410 | Sorb = 5.5 K |
| 1415 | Tower = 1.79 K, warming ~ 0.44 K/hr. 1K Pot = 4.34 K and mostly flat |
| 1425 | Turn up MC heater → 4000 uW |
| 1445 | Tower reached 2.02 K, now flattening. Fridge pressure has started to rise, G1/G2 = 38/24 mbar. Maybe the MC has reached the lambda point. |
| 1445 | Reduce MC heater → 1000 uW |
| 1450 | Turn up MC heater → 2000 uW |
| 1454 | Start 45 min series of +10/0V data (bias applied after 60 sec), at elevated temperature, with 1000 beginning randoms, trigger threshold 30/30/30/60 on DCRC3qI/qO/DCRC1qI/qO, 5Hz in-run randoms, with 1.6384 ms pulses (8192 length) and 400 us prepulse (500 length). Use Sequencer script r74_takeandflash_dcrcbias.msl. This flashes for 30 seconds at end of series. |
| 1454 | Tower = 2.02 K at beginning of series. Tower = 2.28 K at end of series. |
| 1523 | Tower has risen to 2.22 K. Reduce MC heater → 500 uW |
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| 07210922_1454 |
| 1530 | MC = 2.64 K |
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| 1545 | Turn up MC heater → 4000 uW |
| 1625 | Tower = 2.73 K, rising 0.18 K/hr |
| 1625 | Turn off MC heater. Tower starts cooling… |
| 1630 | Turn on MC heater → 1000 uW |
| 1634 | Start 45 min series of +10/0V data (bias applied after 60 sec), at elevated temperature, with 1000 beginning randoms, trigger threshold 30/30/30/60 on DCRC3qI/qO/DCRC1qI/qO, 5Hz in-run randoms, with 1.6384 ms pulses (8192 length) and 400 us prepulse (500 length). Use Sequencer script r74_takeandflash_dcrcbias.msl. This flashes for 30 seconds at end of series. |
| 1634 | Tower = 2.69 K at beginning of series. Tower stayed between 2.68 and 2.70 K throughout series. |
| Adjusting MC heater on the fly to try to keep temperature constant |
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| 07210922_1634 |
| 1745 | Tower = 2.69 K. Turn on MC heater → 1000 uW |
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| 1745 | Close V4a, then switch 4He pump exhaust valve from RECOVER to EXHAUST, then close the red valve from the 4He line to the recovery system. Then turn off 4He pump. |
| 1800 | 1K Pot was at 4.33 K from 14:15 till recently but now has started warming, 5.06 K and rising. G1/G2 = 260/230 mbar, rising slowly. Sorb started rising quickly too at this point, reached 8.6 K by 18:20 |
| 1820 | 1K Pot = 7 K (sensor maximum) |
| 1901 | Start 45 min series of +10/0V data (bias applied after 60 sec), at elevated temperature, with 1000 beginning randoms, trigger threshold 30/30/30/60 on DCRC3qI/qO/DCRC1qI/qO, 5Hz in-run randoms, with 1.6384 ms pulses (8192 length) and 400 us prepulse (500 length). Use Sequencer script r74_takeandflash_dcrcbias.msl. This flashes for 30 seconds at end of series. |
| Tower = 3.05 K at beginning of series, rose to 3.075 K by about the middle then stayed there through the rest. | |
| I opened V9 briefly to let some mixture into the dump, to try to cool the tower because the temperature was rising. |
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| 07210922_1901 |
| 2018 | Start 45 min series of +10/0V data (bias applied after 60 sec), at elevated temperature, with 1000 beginning randoms, trigger threshold 30/30/30/60 on DCRC3qI/qO/DCRC1qI/qO, 5Hz in-run randoms, with 1.6384 ms pulses (8192 length) and 400 us prepulse (500 length). Use Sequencer script r74_takeandflash_dcrcbias.msl. This flashes for 30 seconds at end of series. |
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| Tower = 3.22-3.23 K during series |
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| 07210922_2018 |
| 2108 | Start 20 min series of -10/0V data (bias applied after 60 sec), at elevated temperature, with 1000 beginning randoms, trigger threshold 30/30/30/60 on DCRC3qI/qO/DCRC1qI/qO, 5Hz in-run randoms, with 1.6384 ms pulses (8192 length) and 400 us prepulse (500 length). Use Sequencer script r74_takeandflash_dcrcbias.msl. This flashes for 30 seconds at end of series. |
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| Tower = 3.22-3.23 K during series |
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| 07210922_2108 |
| 2202 | Start 28 min series of +10/0V data (bias applied after 60 sec), at elevated temperature, with 1000 beginning randoms, trigger threshold none/none/30/60 on DCRC3qI/qO/DCRC1qI/qO, 5Hz in-run randoms, with 1.6384 ms pulses (8192 length) and 400 us prepulse (500 length). Use Sequencer script r74_takeandflash_dcrcbias.msl. This flashes for 30 seconds at end of series. |
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| Tower ~ 3.47 K during series | |
| Turned off DCRC3 triggers because they seemed to be causing overtriggering | |
| 2226 | Abort series early, looks like the overtriggering may make the data hard to see. Flash for 60 seconds. |
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| 07210922_2202 |
| 2234 | Start 45 min series of +10/0V data (bias applied after 60 sec), at elevated temperature, with 1000 beginning randoms, trigger threshold 40/30/30/60 on DCRC3qI/qO/DCRC1qI/qO, 5Hz in-run randoms, with 1.6384 ms pulses (8192 length) and 400 us prepulse (500 length). Use Sequencer script r74_takeandflash_dcrcbias.msl. This flashes for 30 seconds at end of series. |
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| Tower 3.48-3.49 K during series |
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| 07210922_2234 |
| 2340 | Open V9 and leave it open to let mixture expand into dump. Pressure was around 600 mbar, and after opening V9 for a minute then closing again it pretty much bounced back. |
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| 2345 | MC heater = 10000 uW and Tower temperature was rising but now it's dropping again, I guess from the expanding mixture. I'll turn off the heater for now, getting late, maybe take more data in the morning. |
| 2345 | Tower = 3.42 K. Turn off MC heater. |