2021/09/23 (Thursday)
- Lab in-personnel: Giulia and Matt
| Status | Run 74 in progress. First cooldown after IVC rebuild. |
|---|---|
| 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/ |
|
| Position of Am source: y = 0.0 mm | |
| Circulation and 1K Pot are off, main bath has boiled away. Mixture is open to fridge and dump (and LN2 Cold Trap 2) | |
| 0700 | Tower = 3.47 K, Sorb = 31.1 K, G1/G2 (fridge and dump) = 550/500 mbar |
| Tower was at 3.6 K at 7:55 but then started rising, to 5.5 K at 8:10 then rose more quickly reaching 11 K by 8:20 then leveling out to around 12.7 K at 8:50 | |
| 0850 | Look at random traces, they look pretty normal. Then apply +3/0 V bias - looks like breakdown noise. |
| 0852 | Start pumping mixture to dump, at first just from the still side, then from both still and condenser side (V3 open). This does not produce a cooling effect, not too surprising. |
| 0958 | Tower/MC/Coldplate = 13254/19333/NaN mK, Still = NaN K / 0.034 mbar / 0 mW |
| 1004 | At 10kHz noise in DCRC3qI/qO/DCRC1qI/qO = 5.7/4.5/8.3/41 8e-6. This is q3/q1/q4/q2 At 3kHz (peak) noise in DCRC3qI/qO/DCRC1qI/qO = 51/19/46/270 e-6. |
| Noise is considerably higher than yesterday. | |
| 1015 | Dump = 731.1 mbar, actually falling a little, probably that's just the atmospheric pressure changing. Close V9, stop pumping out fridge and trap to dump |
| After consultation with Dongming we've decided to try to get more data in the 3-12 K range. So, we should do another LHe transfer - this will be sort of like an initial transfer, MC(Cernox) = 16.7 K currently | |
| 1605 | Fill LN2 cold trap bath |
| 1610 | Let mixture from dump through cold LN2 Trap 2 into fridge, condenser side and still side |
| Probably only need about 10 ubar He exchange gas in IVC… | |
| 1615 | Let some He gas into IVC. Peaks at 10 ubar, but when I close the valve it keeps falling. Meanwhile MC(Cernox) temperature is rising sharply, was 16.7 now 18.5 K and rising. |
| 1630 | Let 6.3 ubar He exchange gas into IVC. MC(Cernox) = 23.5 K and rising |
| 1630 | MC(Cernox)/Sorb = 23.8/55.3 K, IVC = 6.3 μbar, G1(fridge) = 594 mbar. (3He pump is off) |
| 1633 | Begin LHe transfer (with MB empty) |
| 1635 | MC(Cernox)/Sorb = 25.2/56.5 K, IVC = 2.2 μbar, G1(fridge) = 589 mbar. |
| 1640 | Stop DAQ programs and power down DCRCs |
| 1640 | MC(Cernox)/Sorb = 21.8/51.6 K, IVC = 1.2 μbar, G1(fridge) = 579 mbar. |
| 1645 | MC(Cernox)/Sorb = 13.2/37.1 K, IVC = 0.63 μbar, G1(fridge) = 554 mbar. MB = 7.5% |
| 1647 | MC(Cernox) = 10.0 K, IVC = 0.34 μbar. Start pumping out IVC with Turbo pump. |
| 1655 | MC(Cernox)/Sorb = 8.1/7.5 K, IVC = 5.4 nbar, G1(fridge) = 505 mbar. MB = 31.6% |
| MC seems kinda stuck around 8, actually rising a little. Maybe should add exchange gas again… | |
| 1700 | Let 0.63 μbar He into IVC. MC starts cooling again |
| 1705 | MC(Cernox)/Sorb = 7.4/5.3 K, IVC = 0.25 μbar, G1(fridge) = 480 mbar. MB = 59.6% |
| Letting in a little more He exchange gas | |
| 1715 | MC(Cernox)/Sorb = 5.6/5.3 K, IVC = 0.25 μbar, G1(fridge) = 450 mbar. MB = 81.1% |
| 1717 | MC(Cernox) = 5.0 K, IVC = 0.12 μbar. Start pumping out IVC with Turbo pump. |
| 1720 | MC(Cernox)/Sorb = 4.7/5.4 K, IVC = 5.4 nbar, G1(fridge) = 449 mbar. MB = 92.6% |
| 1723 | End LHe transfer @ MB = 90.6% |
| 1725 | MC(Cernox) = 4.58 K, doesn't seem to be rising. |
| 1735 | MC(Cernox)/Sorb = 4.52/5.3 K, G1(fridge) = 506 mbar. |
| Fridge pressure rose a bit after the transfer but probably not a problem. MC continues to slowly cool. | |
| 1740 | Fire up DCRCs, turn on DAQ programs, try applying bias to detector, 0/-5 V. No breakdown, see pulses. Dial HV back to 0V. |
| 1740 | MC(Cernox)/Tower = 4.50/4.33 K |