| 1000 | DCRC31 in DIB1, DCRC33 in DIB2 as yesterday. Zap SQUIDs and set lockpoints and QET biases on DIB1. Tower base is about 74.5 mK with DCRCs powered. |
| | Method: watch pulses on DIB1 as the charge bias is adjusted. This allows us to observe phonon pulses on Side 1 (A, B, C) and Side 2 (D), none of which are outer-ring channels. Note that tables exist relating nominal voltage settings to calibrated voltage settings: bias voltages quoted here are calibrated (true according to the table) voltages. |
| | Interference problem: as with DCRC33 in DIB1, when the interference pattern appears the tower heats up (to 100 mK or more depending on how long it's allow to last) and the DIB1 FETs must be power cycled. What is different though with DCRC31 powering DIB1 is that the tower will continue to heat if the FETs are turned off. They must be on for the tower to cool back to normal. |
| 1058 | DIB1 0V, increase DIB2 bias in -0.5 V steps. Breakdown at 0.0 V / -5.0 V. |
| | Breakdown symptoms: phonon channels just pulse-less noise, charge channels spiky, no normal pulses. Tower temperature increases a few mK. |
| | Charge pulse polarity: right-side-up for -/+ biases, upside-down for +/- biases. |
| 1058 | DIB1 0V, increase DIB2 bias in +0.5 V steps. Breakdown at 0.0 V / +9.5 V. |
| | At 4.0 V and greater on DIB2, changing the voltage causes the phonon pulses to disappear for a few seconds, as if the adjustment briefly warms them out of s/c. Phonon channels on the side being adjusted disappear for longer. |
| 1135 | Try stepping down DIB2 bias. Pulses return at 8.0 V, and repeated breakdown at 0.0 V / +8.5 V. |
| 1156 | DIB2 0V, increase DIB1 bias in -0.5 V steps. No breakdown all the way to -8.0 V. But at this point interference occurs, then breakdown. |
| 1204 | Try stepping down DIB1 bias. Pulses return at -3.5 V, and breakdown at -4.0 V / 0.0 V. |
| 1215 | Power off DCRCs and allow tower to cool for a while |
| 1427 | DIB2 0V, increase DIB1 bias in +0.5 V steps. No breakdown all the way to max possible: pulses still at +13.0 V / 0.0 V. |
| | very frequent recurrences of the interference pattern during this run, more than twice a minute on average. |
| 1451 | Increase DIB1/DIB2 voltages symmetrically in -0.5/+0.5 V steps. Breakdown at -8.5 V / +8.5 V. |
| | very frequent recurrences of the interference pattern again. |
| 1511 | Try stepping down biases: must decrease to -3.0/3.0 V to restore pulses. Breakdown at -4.0 V / +4.0 V. |
| 1451 | Increase DIB1/DIB2 voltages symmetrically in +0.5/-0.5 V steps. Breakdown at +5.5 V / -5.5 V. |
| 1714 | Try letting tower cool for a while then try repeating large -/+ bias, by immediately setting them from 0 rather than in steps. OK at -4.0 V / 4.0 V but breakdown at -6.0 V / 6.0 V. (Didn't try anything between them.) |