2016/05/11 (Wednesday)
| Setup: HV mode, DIB1/2/3 → -/Switchboard PA&PB QET bias&ret off/Open → cables → 3.2MHz Filters → HV board → HV1/HV2 → DCRC55(1)/50(3), DCRCs off overnight | |
| Tower temperature stable overnight | |
| 0910 | Tower/MC/Coldplate =46.4/43.1/282 mK, Still = 1.17 K / 0.080 mbar, G1/G2 = 115/110 mbar, 1K Pot = 1.54 K / 2.4 mbar, Main Bath = 44.9% |
| 0915 | Fill LN2 cold trap bath |
| 1000 | Taking a more careful look at DIB3's leakage. Leakage measured immediately after bias change and again ~2-5min later, when it seems to have reached a stable value. |
|---|
| Bias [V] | Leakage [mV] | Tower Temp (mK) |
|---|---|---|
| DIB3 with diverter board connected. All others floating. | ||
| 0 | 0 | 46.3 |
| 4.995 | 7→1.6 | 46.6 |
| 10.00 | 10.6→3.0 | 46.6 |
| 15.00 | 11.6→8.7 | 47.1 |
| 20.01 | 17.0→16.1 | 47.7 |
| 25.00 | 26.3→24.9 | 49.0 |
| 0 | -3.6 | 46.5 |
| 1115 | We're suspecting a path to ground in one of the QET bias/ret lines, specifically DIB2 PA. Measure this resistance directly by connecting cable to breakout box and using multimeter to test QET lines to chassis. |
|---|
| Cable unplugged from ebox | ||
|---|---|---|
| Any QET→chassis | 0.07 nS | 14 GΩ |
| Raw Conductance | Corrected Resistance (=raw-0.07nS) | |
|---|---|---|
| DIB 1 QET→chassis | ||
| PA | 0.14 nS | 14.3 GΩ |
| PB | 0.13 nS | 16.7 GΩ |
| PC | 0.13 nS | 16.7 GΩ |
| PD | 0.11 nS | 25.0 GΩ |
| DIB 2 QET→chassis | ||
| PA | 0.70 nS | 1.6 GΩ |
| PB | 0.18 nS | 9.1 GΩ |
| PC | 0.16 nS | 11.1 GΩ |
| PD | 0.17 nS | 10.0 GΩ |
| DIB 3 QET→chassis | ||
| PA | 0.17 nS | 10.0 GΩ |
| PB | 0.14 nS | 14.3 GΩ |
| PC | 0.13 nS | 16.7 GΩ |
| PD | 0.12 nS | 20.0 GΩ |
| 1340 | Tower/MC/Coldplate = 46.2/43.1/268 mK |
|---|---|
| 1350 | Bang fridge from from west. CP spikes to 278 over 30 seconds then falls to 255 mK after 3 minutes. |
| 1355 | Tower/MC = 45.3/42.6 mK. So banging the fridge may have helped slightly |
| 1415 | Tower/MC = 43.9/40.8 mK. Then stays flat for the next hour. |
| 1600 | Measure some resistances between phonon channels (QET bias pins) using FLUKE 87V multimeter in nS scale: |
| DIB1 | DIB2 | DIB3 | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| pA | pB | pC | pD | pA | pB | pC | pD | pA | pB | pC | pD | |||
| DIB1 pA | ||||||||||||||
| DIB1 pB | 1.1 [a] | |||||||||||||
| DIB1 pC | 0.13 | 0.14 | ||||||||||||
| DIB1 pD | 0.11 | 0.12 | 0.16 | |||||||||||
| DIB2 pA | 0.18 | 0.05 | ||||||||||||
| DIB2 pB | 0.26 | 40 [b] | ||||||||||||
| DIB2 pC | 0.11 | 0.1 | ||||||||||||
| DIB2 pD | 0.13 | 0.1 | 0.12 | |||||||||||
| DIB3 pA | 0.16 | 10 [c] | 0.11 | |||||||||||
| DIB3 pB | 0.16 | |||||||||||||
| DIB3 pC | 0.08 | 0.14 | 24 [d] | |||||||||||
| DIB3 pD | 0.16 | 0.06 | 0.15 | 0.13 | 0.14 | |||||||||
| [a] Starts higher, then drifts down after a minute. Inner and central Side1 channels | ||||||||||||||
| [b] Temperature spikes to 50 mK. Outer and central Side2 channels | ||||||||||||||
| [c] Temperature spikes to 46 mK. Adjacent central Side2 channels (different DIBs) | ||||||||||||||
| [d] Temperature spikes to 47 mK. Inner and central Side2 channels | ||||||||||||||
- So it seems there are some low resistance paths between some adjacent channels, but not between every adjacent pair.
- No opposite-side pairs have low resistance paths
- Low resistance paths are not limited to same-DIB channels
| 1800 | Fill LN2 cold trap full. |
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