| 0915 | Filled LN2 cold trap bath. |
| | MC/Tower: 33.3/45.2 mK. Still: 95 μbar. G1/G2: 119/119mbar. 1K Pot: 1.535K / 5.0 mbar. Main bath = 38.0% |
| 1120 | Attempting to repeat yesterdays measurements of breakdown at negative Qbias voltages, apply -10.00V with HV supply, leakage is -2.3mV → -8.99Vcrystal. No signs of breakdown. |
| | Apply -14.00V with HV supply, leakage measured at -3.1mV → -12.64Vcrystal. No breakdown. |
| | Apply -16.03V, leakage measured at -4.2mV → -14.18Vcrystal. No breakdown. |
| | Apply -17.00V, leakage measured at -3.6mV → -15.42Vcrystal. No breakdown. |
| | Apply -18.01V, leakage measured at -4.0mV → -16.25Vcrystal. No breakdown. |
| | Apply -19.00V, leakage measured at -5.5mV → -16.58Vcrystal. Right when the Voltmeter read -19.00V, DIB1 Qo began showing signs of breakdown. When measuring the leakage it would show a value for a few seconds then begin increasing, stopping on another value for another second, then increasing again. This occurred several times until it finally settled at -5.5mV. |
| 1135 | Lower HV to -17.84V, leakage measured at -5.5mV → -15.42Vcrystal. Breakdown signs have gone away. |
| 1145 | Set HV back to 0V, and flash detector for 60s. |
| 1430 | Use switch board to turn off DIB 1 QI bias, source, drain and feedback (Switches 9-3, 9-4, 10-2, 10-5, respectively). Disconnect DCRC 3. Start 15 minute test series, reading out only DIB1 (Qouter pulses, all else should be noise) at 0 V Bias with 30s initial flash and 25min cooldown. Triggering on DIB1 Qo at 60ADC bins. 1000 randoms before and after. |
| 1520 | Stop sequencer before it begins another 15 minute run. Time to attempt applying symmetric biases to the crystal to see how high we can get before breakdown. |
| 1535 | After reconnecting the lines switched off before the 15min run, apply 5V using the DCRCs and -5.004V using the HV supply. Leakage is -2.9mV → (-3.728 + -5)Vcrystal = -8.73Vcrystal. |
| 1540 | Apply 8V using the DCRCs and -8.00V using the HV supply. Leakage is -4.2mV → (-6.15 + -8)Vcrystal = -14.15Vcrystal. |
| | Apply 10V using the DCRCs. Breakdown occurs without a chance to adjust HV supply voltage. Leakage is measured at -3.5mV. This total (nominal) voltage (i.e. ~18V) is consistent with when we saw breakdown in this direction when applying an asymmetric Qbias. Bring voltage back to 0V and flash for 30s. |
| 1625 | Apply -5V using the DCRCs and +5.003V using the HV supply. Leakage is 1.1mV → (4.52 + 5)Vcrystal = 9.52Vcrystal. No breakdown. |
| | Apply -7V using the DCRCs and +7.00V using the HV supply. Leakage is 1.7mV → (6.25 + 7)Vcrystal = 13.25Vcrystal. No breakdown. |
| | Apply -8V using the DCRCs and +8.00V using the HV supply. Leakage is 0.5mV → (7.78 + 8)Vcrystal = 15.78Vcrystal. No breakdown. |
| | 60s later, measure leakage again at same voltages. Leakage: 1.5mV → (7.34 + 8)Vcrystal = 15.34Vcrystal. Not sure what made the leakage temporarily drop to such a low value. |
| | Apply -9V using the DCRCs. Breakdown occurs before HV supply can be adjusted. Leakage is 2.7mV → (6.82 + 9)Vcrystal = 15.82Vcrystal. |
| 1640 | Unpower DCRCs and commence warm up procedure. Pump mixture to dump and isolate, then turn off 1K Pot. Cease recovering exhaust of 1K Pot pump. Turn on Mixing Chamber Heater to 20mW. |
| 1655 | Begin closing V6. When V6 is closed, close V9, turn of He3 pump, and open V14 and V4 to open both sides of the fridge to the dump for slow warm up overnight. In the morning, we'll finish pumping all the mixture to the dump. |
| 1732 | Fill LN2 cold trap full. |