2018/07/16 (Monday)
| Setup: DIB1/3/4 → 3.2 MHz filters 2/3/1 → cable 3/1/2 → gender changer 3/?/2 → HVConn 1/3/2 → HV 1/2 → DCRC55(1)/DCRC50(3) | |
| 0932 | Tower/MC/Coldplate = 33.7/31.0/191 mK, Still = 1.5 K / 0.140 mbar / 4 mW, G1/G2 = 144/137 mbar, 1K Pot = 1.59 K / 18 mbar. MB = 69.8% |
| 0936 | Fill LN2 cold trap full. |
| 0940 | Set HV=40V with 15% prebias for 5 min using script changeHV_0_40_preBias15_5.msl |
| 0950 | All channels are currently railed. Relocking them works. All channels are showing lots of jagged pulses. Kinda looks like breakdown noise, that's strange. |
| 1000 | Apply QET bias settings chosen at 100 V from 2018/06/01 |
| channel | QET bias [uA] |
|---|---|
| DCRC1pA | 290 |
| DCRC1pB | 270 |
| DCRC1pC | 315 |
| DCRC3pB | 140 |
| DCRC3pC | 315 |
| DCRC3pD | 310 |
| 1001 | Still seeing breakdown noise in all channels. Seeing an apparent rate of ~10 events/3.2768 ms in randoms. Can't really take data like this, so I'll just let it sit for a while and see if it settles. |
|---|---|
| 1030 | Tower = 31.3 mK and cooling. Still seeing breakdown noise. |
| 1055 | Looks like breakdown noise still. Dial HV down to 0 V using sequence script changeHV_40_0.msl, we'll see what happens. |
| 1215 | HV = 0 now but jagged noise is still present. It must not be breakdown noise. |
| 1228 | Zap SQUIDs |
| 1238 | Jagged noise still present. Disable Logging of HP 3478A and Keithley in OMNI_Logger. Switch off Keithley and HP multimeters. Noise remains. Switch off HV supply. Noise remains. Power HV supply and multimeters back on, restore multimeter logging. |
| 1340 | Jagged noise still present. Let's try turning some things off while watching DCRC1PA. Set all QET biases=0 uA except DCRC1PA. Noise remains on DCRC1PA. Look at DCRC1PB, which is now SC. There is a small, but coherent ~300Hz oscillation in the baseline. This baseline oscillation is improved by switching off the HV power supply. That doesn't fix the jagged transition noise though. |
| 1350 | Restore QET biases to the above values. |
| 1355 | Stop DCRC programs, power cycle DCRCs 1,3. Restart DCRC programs. Tower spikes to 165 mK, but cools quickly to ~33 mK. |
| 1405 | Jagged noise is still present. [image not archived: doubt.svg] |
| 1410 | Try triggering on DCRC3pD rather than looking at randoms. See a lot of spike-like pulses. Not many strong pulses, which is strange. |
| 1415 | Try turning 15V Power off on DCRC3. No change in noise pattern or temperature with 15V Power on or off on DCRC3 Try turning 15V Power off on DCRC3. Temperature rises to 300 mK. Turn power on again, temperature falls again. |
| 1420 | With tower still hot, we continue to see spike-like pulses even though the channels are normal, no event-like pulses. |
| 1430 | Adjusting the QET bias downward on DCRC3pD we no longer see the spikes and see more regular pulses. But there's lots of jagged noise (that looks a bit like low energy very-high-rate events) |
| 1435 | Zap SQUIOs on DCRC1,3 twice. Haven't done that since the power cycle. |
| 1445 | Can see strong pulses, but lots of the jagged noise still, many small pulses in every trace. (Also we clearly have the timing link working.) |
| 1450 | Try turning off DCRC4 (turn off DAQ programs, disable DCRC4 in ODB, unplug DCRC4, turn programs back on). Still seeing jagged noise in all channels. |
| 1455 | Try disabling DCRC3 and view pulses on DCRC1. Jagged noise still present. |
| 1455 | Try disabling DCRC1 and view pulses on DCRC3. Jagged noise still present. |
| 1505 | Reenable and restart all three DCRCs. |
| 1505 | Zap SQUIDs again. |
| 1525 | Still pressure is only 0.13 mbar. Let's see if we can improve base temperature by kicking up still power. Increase still power 4→6 mW |
| 1545 | Tower cooled a bit, 31.7 → 31.1 mK. Not dramatic. |
| 1550 | Pulses on DCRC1 look good but noise still present, really looks a lot like a very high rate of low-energy events. DCRC3 channels are all railed for some reason… actually DCRC3 channels are railed at a random value: -0.15 V. That seems like a frozen DCRC. Hrm. in telnet session on DCRC3, neither rd 0 nor rd 14 are updating. |
| 1605 | Stop DAQ programs and power cycle DCRC3 |
| 1615 | DCRC3 still seems stuck. Try turning off programs, disable all but DCRC3 and set to master, restart programs: now DCRC3 working. |
| 1615 | Noticed timing link cable was not fully inserted in DCRC1. Reseat this then enable and restart with all 3 DCRCs, now all are working. Noise in the form of high low-energy event rate is still present. |
| 1635 | Start a 5-minute bake on DCRCs 1&3 |
| 1645 | Fill LN2 cold trap bath |