2017/01/27 (Friday)
| Setup: DIB1/3/4 → 3.2 MHz filters → cables → DCRC55(1)/33(2)/50(3) | |
| 0900 | Tower/MC/Coldplate = 58.5/34.2/200 mK, Still = 1.3 K / 0.110 mbar, G1/G2 = 140/140 mbar, 1K Pot = 1.70 K / 32 mbar, Main bath = 34.7%. |
| 0905 | Fill LN2 cold trap. |
| 0905 | Disable 15V Power on all three DCRCs (ODB/Equipment/Tower01/Settings/DCRC1,2,3/LED/Enable15VPower : n). Tower temperature climbs to 760 mK. It does not seem to be falling. After a few minutes it's still oscillating around 800 mK |
| 0910 | Turn the 15V Power back on on all 3 DCRCs. Does not seem to bring temperature down right away. MC = 160 mK. After a minute Tower temperature seems to be falling, below 170 mK |
| 0925 | Tower has fallen back to 60.8 mK. Try again to disable 15V power on DCRC1. Temperature begins to climb. Re-enable power, after 10 seconds temperature falling again. Peaked at 360 mK. |
| 0935 | Tower = 57.4 mK and falling. Weird, lower than this morning… possibly that's just because the still got hotter and the fridge is working harder. |
| 0945 | Tower = 53.5 mK and falling. Now condenser and still pressures have fallen close to their values before. Strange that it's still getting colder. |
| 1000 | Tower/MC = 51.3/33.7 mK |
| 1015 | Tower = 51.0 mK, looks pretty flat now |
| 1030 | Establish strong pulses on DCRC1 channels with QET biases set to 110/120/110/110 μA on pA/B/C/D |
| 1035 | Establish strong pulses on DRCR3 with QET biases set to 130/140 μA on pC/D. But pA/B still seem to be unresponsive to changes in QET bias. |
| 1040 | We seem to have lost communication with DCRC2. No response to changes in QET bias and no response in telnet session. Also DCRC_driver program stopped, though strangely we were still getting traces in the pulseviewer. |
| 1040 | Tower = 50.8 mK |
| 1045 | Turn off programs triggerfe2, towerfe3_01, dcrc_driver01. Then unplug power from DCRC2 and DCRC3. (Trying to see whether the problems in the DCRC3 channels may have been that the DCRC was in a bad state.) Plug in power to DCRC2 and DCRC3 Turn on programs dcrc_driver01, towerfe3_01, triggerfe2. |
| 1105 | Establish strong pulses on DCRC2 with QET biases set to -115/-120 μA on pB/C. But pA seems unresponsive. (pD of course is not connected.) |
| 1345 | Tower = 50.6 mK |
| 1430 | Looking a little at SQUID tuning. Twice now we have gone through the SQUID tuning procedure on DCRC3pC, and both times it looked fine for a while but then suddenly all DCRC3 channels railed. The first time they went flatline at a non-extreme, at 0.5 V for some reason rather than at an extreme 1.25 V. After the first time we power cycled DCRC3 since we couldn't think of any other way to fix it. After the power cycle it seemed to be back to normal. |
| 1440 | Tried another power cycle. This time the channels all came back flatlined, and not at 1.25 V but rather at 0.025 volts. |
| 1445 | After another DCRC3 power cycle it looked OK. Then after adjusting some things for SQUID tuning (turning on test signal, connecting to pC feedback, changing from feedback output to readout output) again all channels flatlined, this time at -0.5 V. |
| 1452 | Start LHe transfer (24.4%) |
| 1500 | After power cycling DCRC3 again things look fine. This time just turn on the signal generator at 201 mVpp, 100 Hz. After 2 minutes all channels go flatline at 0.03 V. |
| 1510 | After power cycling DCRC3 yet again things are OK. This time just change pC ADC source to preamp. After 1 minute all channels go flatline at -0.9 V. (Are they just going dead every few minutes? Next time try doing nothing.) |
| 1515 | After power cycling DCRC3 yet again things look OK. Watch pC trace for 6 minutes - still it remains OK. |
| 1525 | Start adjusting QET biases on DCRC3. pC seems unresponsive to changes in QET bias, much like pA and pB before - but pD responds and pulses can be seen. Then after a few minutes all channels go flatline again at -0.5 V. I don't think DCRC3 is doing well. |
| 1525 | Stop LHe transfer because 250L Dewar was empty |
| 1533 | Restart LHe transfer (24.5%) |
| 1555 | Turn off DCRC1 (DCRC3 is off too). Then plug DIB4 into DCRC1 to see whether the channels look better on a more well-behaved DCRC. Set the SQUID settings on DCRC1 appropriate for DIB4's SQUETS. |
| 1605 | With DIB4/3 connected to DCRC1/2, Tower temperature increased to 58 mK, slowly falling |
| 1615 | Now that we are reading DIB4 with DCRC1, pB is responding to changes in QET bias just like pC and pD. But pA is still not responding. |
| 1655 | Looked at SQUID tuning on DIB4 pA and pB. Was able to tune SQUIDs on both. However on pA after tuning the SQUIDs found that it was still unresponsive to changes in QET bias. Also unresponsive to connecting the test signal to QET. So could be at the detector (broken wirebond) or in the cold electronics or something. |
| 1705 | Tower has been hanging at 57 mK. Turn off DCRC1 15V power, and DCRC2 15V power. This time the temperature is going down. 52 mK and falling. |
| 1705 | Finish LHe transfer (94.1%) |
| 1709 | Fill LN2 cold trap full. |
| 1710 | Although DIB4pC is responsive, it shows only weak pulses. Not nearly as strong as DIB4pB and pD. |
| Setup: DIB1/3/4 → 3.2 MHz filters → cables → nothing/33(2)/DCRC55(1) | |
| 1715 | Tower = 49.4 mK |
| 1720 | First indication of 10 kHz oscillations, now that we are colder, in DIB4pD, very strong at certain QET biases (142 μA), not present at 140 μA |