2015/09/22 (Tuesday)
| Current setup: iZIP mode, DIB1/2/3 → cables → 3.2 MHz filters → → DCRC55/33/50. | |
| Overnight: DCRCs unpowered. Cf source near detector for activation. Tower temperature stable. | |
| 0930 | Fill LN cold trap Dewar |
| 0935 | Tower/MC(H35)/MC sensor/Cold Plate = 30.3/24.0/39.1/148 mK, Still = 1.28 K / 0.075 mbar, G1/G2 = 150 mbar, 1K Pot = 1.73 K / 22 mbar, Main bath = 65.3% |
| 1100 | MIDAS tests done. With DCRCs powered, tower temperature has risen from ~30.2mK to ~31.0mK. -/+4V bias still applied. Zero Qbias and flash for 30s. |
| 1133 | Put Cf-252 source back in safe. |
| 1135 | No sinusoidal noise visible on channels. Everything ready for taking long trace noise data (50ms) at the three QET bias states. Transition bias will be first: |
| 1140 | Set MultiDAQ to take 2000 randoms at 0V Qbias, 5/2/5 Frontend Gain, 3 Output Gain, and transition QET biases. Fridge temperature at 31.3mK instead of 31.0mK. |
| Event Rate is ~0.8Hz. Experiment with setting phonon thresholds all to 65 ADC bins, and rate increases to ~0.9Hz, despite the fact that randoms shouldn't depend on trigger thresholds… | |
| 1218 | Stop data after 2000 randoms. Set QET biases to 0. |
| 1230 | Adjust Driver Offsets temporarily to unrail channels. Take 2000 randoms of 50ms superconducting data. |
| 1315 | Stop data. Apply 400uA QET bias to all phonon channels. |
| 1335 | Start 2000 randoms of 50ms traces at normal resistance. |
| 1427 | Stop data. Set channels back to transition QET biases. Give over DAQ control to MIDAS for tests. |
| 1548 | MIDAS tests done. -/+4V bias still applied. Flash 30s. |
| 1624 | Start asymmetrical breakdown studies: |
| Q Side 1[V] (Nominal) | DIB1pA baseline | DIB1pB baseline | notes |
|---|---|---|---|
| 0 | -0.81 | -0.88 | |
| 2 | -0.81 | -0.88 | |
| 4 | -0.81 | -0.88 | |
| 6 | -0.79 | -0.84 | baselines jump then settle |
| 7 | -0.78 | -0.83 | baselines settle more slowly† |
| 8 | -0.75 | -0.77 | jump then settle slowly |
| 9 | -0.73 | -0.78 | jump then settle slowly |
| 10 | - | - | Temporary breakdown. Jagged noise in phonon pulses, then returns to normal. |
| 11 | - | - | Breakdown for real |
| 10 | -0.78 | -0.85 | Back to ok pulses and noise. |
| 0 | -0.82 | -0.85 | back to ok |
| -6 | -0.82 | -0.85 | |
| -8 | -0.82 | -0.85 | |
| -10 | -0.82 | -0.85 | slight baseline jump, relaxes quickly |
| -11 | -0.80 | -0.88 | slight baseline jump, relaxes quickly |
| -12 | -0.80 | -0.85 | bigger jump |
| -13 | -0.80 | -0.85 | bigger jump |
| -14 | -0.80 | -0.85 | bigger jump |
| †NOTE: Probably unrelated, but we temporarily saw “shark-fin” pulse distortion. |
| 1644 | Return Side 1 Qbias to 0V. Apply bias to Side 2 now while monitoring DIB1 channels: |
|---|
| Q Side 2[V] (Nominal) | DIB1pA baseline | DIB1pB baseline | notes |
|---|---|---|---|
| 0 | -0.82 | -0.90 | |
| 2 | -0.82 | -0.90 | |
| 4 | -0.82 | -0.90 | baseline jumps slightly, then settles |
| 6 | -0.78 | -0.85 | big jump, some jagged noise, goes away after ~5s |
| 8 | -0.81 | -0.88 | jagged noise - Breakdown |
| -4 | -0.82 | -0.90 | |
| -6 | -0.82 | -0.90 | baseline jumps slightly, then settles |
| -8 | -0.75 | -0.82 | big jump, then settles |
| -10 | -0.76 | -0.85 | big jump, jagged noise, goes away after ~15s |
| -12 | -0.74 | -0.80 | big jump, jagged noise, goes away after ~30s |
| -14 | -0.73 | -0.79 | pulses disappear briefly (driver normal?), jagged noise, gets smaller after ~1min, baseline remains erratic |
| Side 1 [V] | Side 2 [V] | notes |
|---|---|---|
| -6 | +6 | baselines normal, no breakdown |
| -10 | +10 | big jump, pulses disappear, noise in charge channels, 15s pulses return, but jagged noise persists: Breakdown |
| +8 | -8 | temporary disturbances, baselines up ~0.02V |
| +12 | -12 | Noise in charge, phonons disappear, 5s: charge noise disappears, 15s: phonons show persistent jagged noise, Breakdown |
| 1722 | Flash 30s. Set DAQDAQ to take 4 cycles of -/+2V then -/+4V background data overnight with usual settings (FG=5/2/5, OG=3) and phonon thresholds from yesterday. |
|---|---|
| 1730 | Fill LN2 cold trap full. |
| 1817 | Start data run. |