2021/07/09 (Friday)
- Lab in-personnel: Matt, Pramod
| 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/Source_mover_board+HV_diverter_board → DCRC50(3)/55(1). Kepco 40V supplye → HV BNC. No lead/poly shield. DCRCs on. | |
| 1100 | Tower/MC/Coldplate = 107/33.3/194 mK, Still = 1.41 K / 0.080 mbar / 0 mW, G1/G2= 237/217 mbar, 1K Pot = 1.63 K / 22±2 mbar. MB = 30.7% |
| 1105 | Fill LN2 cold trap bath. |
| 1210 | Messing with DCRC55(1) connections, trying to improve noise. Swapped out the gender changer at the end of cable 3 for a different one, noise seems to be better. |
| 1215 | At 10kHz noise in DCRC3qI/qO/DCRC1qI/qO = 1.8/1.2/1.7/6.1 e-6. This is q3/q1/q4/q2 At 3kHz (peak) noise in DCRC3qI/qO/DCRC1qI/qO = 27/4.3/2.9/40 e-6 |
| 3kHz noise is higher in the bad channels, but a lot of the channels have better noise than yesterday. | |
| 1221 | Start 82 min series of 0V/-15V (bias applied after ~2 min), with 1000 beginning randoms, trigger threshold 35/30/35/40 on DCRC3qI/qO/DCRC1qI/qO, 5Hz in-run randoms, with 1.6384 ms pulses (8192 length) and 400 us prepulse (500 length). Start sequence with Start button. |
| 1338 | Dial bias down to 0 V |
| 1345 | Flash detector for 60 seconds. Tower thermometer peaks @ 0.43 K |
| 1508 | Start LHe transfer @ MB = 23.4% |
| 1547 | End LHe transfer @ MB = 92.5% |
| Currently there are major issues with the Linux cluster because Chad is swapping out a new drive for /data/chocula. We can't process data or start MIDAS. | |
| Today's data is partially processed - we see evidence of the 60 keV line in q3, with time-dependent impact ionization. This suggests that the source is toward the far endstop. We thought it was at the near endstop before the last move, and we moved it far enough to be at the center. But it seems that we were wrong, and we'll need to move it again to return it to the center. Assuming this is correct then currently the source is at -28.16 mm, which is in the q3 territory. | |
| 1709 | Do mvNwait +4steps×427 times, 35 second wait, with dwell = 40 and power = 6.8 V. (Around 6.78 mm/hour.) This is a total distance of 28.16 mm and should end at 9:18 pm. Strangely, the temperature is not going up nearly as high as the last move sequence (which was slower). After 12 minutes MC is only at 89 mK. V_trimpot = 6 Vpp, Vpower = 7.4 Vpp. |
| 1725 | Try looking at the 2nd motor coil on the scope - it looks all screwed up. Crap. |
| 1730 | Abort move sequence after 34 moves |
| 1735 | Looks like the wires for the second coil broke off at the diverter board. These are orange and brown. |
| 1815 | Resolder those two connections. I think I got them in the correct order. Brown is nearer to the trim pot.  |
| 1820 | Tried mv +4, then mv +8×4 times weird results in the waveforms. Looks like sorta normal steps but on the final step the voltage does not return to zero… also amplitudes are higher and there is a rampup on the square tops and bottoms. |
| 1830 | On the second coil the waveforms look normal. |
| 1850 | Discover one broken wire from the first coil at the board. Resolder this one too. |
| 1853 | Try mv +8. Looking at first coil. Waveforms seem back to normal. V_trimpot = 6.2 Vpp, Vpower = 7.4 Vpp. |
| 1853 | Try mv +8. Looking at second coil. Waveforms look normal. V_trimpot = 5.6 Vpp, Vpower = 7.6 Vpp. |
| We're going to move back to the endstop (which we think is actually the far endstop), moving as many steps as we've moved away from it. But only the good moves - we are not sure if any of today's moves worked. So just -4×200 steps. We may need to go an additional -4×47 steps to get all the way to the endstop. (Or maybe just -4×13 if only the later moves today worked.) | |
| 1913 | Do mvNwait -4steps×200 times, 35 second wait, with dwell = 40 and power = 6.8 V. (Around 6.78 mm/hour.) This is a total distance of 16.29 mm and should end at 9:09 pm. Second coil: V_trimpot = 5.6 Vpp, Vpower = 7.5 Vpp. After 4 minutes MC is at 126 mK and rising. After 10 minutes MC temperature peaked at 183 mK, then settled to an average of 180 mK and stayed there for the full sequence, ending at 9:11 pm. Condenser pressure increase from 245 to 295 mbar, sloping upward slightly for the rest of the sequence. Maybe this is on the edge of the fridge not being able to keep up. |
| Plots from today's data: | |
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| Looks pretty clear that the 60keV line is in q3. Which makes perfect sense if the source was at the far endstop before the last move. | |