2021/06/30 (Wednesday)
- Lab in-personnel: 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/Source_mover_board+HV_diverter_board → DCRC50(3)/55(1). Kepco 40V supplye → HV BNC. No lead/poly shield. (actually currently DCRC55(1) is disconnected. DIB2+acc→SL43→filter→cable3→Source_mover_board) | |
| 1240 | Tower/MC/Coldplate = 187/33.5/189 mK, Still = 1.33 K / 0.080 mbar / 0 mW, G1/G2= 235/212 mbar, 1K Pot = 1.63 K / 22±2 mbar. MB = 64.5% |
| 1245 | Fill LN2 cold trap bath |
| Yesterday we moved the source away from the far endstop and toward the near endstop. Currently the estimated position of the source is y = 2.97 mm. The near endstop is at y = +13.12 mm. We moved a total of 35.3 mm yesterday. Using a few different move-and-wait modes yesterday, we found that at 9.5 mm/hour and faster the fridge couldn't keep up, in the sense that the max and min of the Tower temperature spikes kept creeping up and the circulation pressures kept creeping up. A rate of 3.2 mm/hour however was cryogenically stable. Maybe today we can try something in between. |
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| 1252 | Do mvNwait -32steps×8times, 8 minute wait, with dwell = 40 and power = 7.2 V. (Around 4.0 mm/hour.) Should finish at 1:46 pm. First move: V_trimpot = 6.8 V peak-to-peak, Vpower = 8.0 Vpp. These have changed again - yesterday at some point Vtrimpot went down (and Vpower went up), now they're back at their earlier values. First Tower peak @ 2.55 K, minimum before next spike = 0.65 K |
| 1430 | The last 7 peaks were nice and uniform, spikes 2.71-2.73 K, minima 0.69-0.75 K. (These are lower than the minima from last night, which is weird because those were 10-minute waits, these are 8-minute waits. But I know I can't totally trust this thermometer.) Condenser pressure rose from 220 mbar to 260 mbar and basically plateaued. Still plateaued around 0.095 mbar. |
| 1435 | Tower has cooled to 200 mK, 48 minutes after the last move. |
| 1524 | Do mvNwait -32steps×8times, 6 minute wait, with dwell = 40 and power = 7.2 V. (Around 5.3 mm/hour.) Should finish at 4:12 pm. First move: V_trimpot = 6.6 V peak-to-peak, Vpower = 8.0 Vpp. First Tower peak @ 2.58 K, minimum before next spike = 0.88 K |
| 1615 | The last 7 peaks were pretty much uniform, spikes 2.73-2.78 K, minima 0.90-1.10 K. Condenser pressure rose from 232 mbar to 264 mbar. Still plateaued around 0.10 mbar. |
The two moves today:   |
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| The source mover should now be at y = 11.41 mm, 1.72 mm from the near endstop. Let's set up for 8-step moves, watching the temperature pattern as before. We'll move it far enough so that it should hit the near endstop, and as before we can watch for lower temperature spikes. Of course we can also look at the endstop-to-chassis resistance in case this one happens to be plugged in correctly. |
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| 1626 | Do mvNwait -8steps×18times, 3 minute wait, with dwell = 40 and power = 7.2 V. (Around 2.6 mm/hour.) Should finish at 5:20 pm. First move: V_trimpot = 6.6 V peak-to-peak, Vpower = 8.0 Vpp. First Tower peak @ 1.40 K, minimum before next spike = 0.91 K |
| I expect the source to contact the near endstop after the 13th move (at 5:05 pm). Each 8-step move will move it 0.13 mm further. | |
| 1643 | 6 moves done. Tower peaks are close to 1.64 K, minima close to 1.07 K. Those peaks are pretty similar to two days ago when we were approaching the far endstop. |
| 1710 | 15 moves done. The peaks have not fallen yet. The endstop-to-chassis resistances still read <0.2 nS. The source should be about 0.26 mm past the near endstop now. |
| 1720 | All 18 moves done. The peaks are still just as high. The endstop-to-chassis resistances still read <0.2 nS. The source should be about 0.66 mm past the near endstop now. Hmm. |
| Also today: receive SiHV detector S104 from Matt Cherry. In a bag in a box, with lots of bubble wrap. Matt C did not follow any particular wiring diagram, he just wirebonded the detector channels to whatever DIB channels. He wired all 12, using charge channels on the DIBs in one case. We can deal with this if we use wires for DIB-to-tower instead of side coaxes. |