2016/03/07 (Monday)
| Setup: iZIP mode, DIB1/2/3 → cables → 3.2 MHz filters → DCRC55/33/50 | |
| Idle overnight, DCRCs powered | |
| 0845 | Tower/MC(H35)/MC sensor/Cold Plate = 31.3/27.5/41/157 mK, Still = 1.18 K / 0.090 mbar, G1/G2 = 130/130 mbar, 1K Pot = 1.57 K / 4.0 mbar, Main bath = 42.5% |
| 0855 | Fill LN2 cold trap Dewar |
| 0900 | Perform mini-IbIs in standard 3-Dsub-filter setup with correct QET and SQUID settings. |
| 0925 | Prepare for Tc measurement. Set QET biases to 0. Many channels rail… |
| 0935 | Restore all phonon channels with relocks and driver offset (aka ADCOffset) adjustments. |
| 0945 | Use SQUIDtuning GUI to connect test signal at 12 Vpp, 100 Hz to all phonon channels. |
Measured Tc's one DCRC at a time, raising the temperature until all four phonon channels went from s/c to transition to normal, then cooling until they all went back to s/c. Modified MC heater power in steps, maximum 30 mW. Click between the four channels to observe waveform during temperature sweeps.
| G106a Tc | Tower temperature (mK) | |||
|---|---|---|---|---|
| heating | cooling | |||
| Channel | s/c→trans | trans→normal | normal→trans | trans→s/c |
| DIB1 pA | 85.3 | 85.9 | 85.0 | 84.0 |
| DIB1 pB* | 86.7 | 88.7 | 88.2 | 86.1 |
| DIB1 pC | 85.0 | 86.1 | 85.8 | 82.9 |
| DIB1 pD | 82.9 | 84.5 | 83.7 | 81.8 |
| DIB2 pA | 83.3 | 84.1 | 83.6 | 81.9 |
| DIB2 pB | 90.4 | 90.8 | 90.1 | 88.9 |
| DIB2 pC | 86.3 | 87.8 | 87.1 | 85.9 |
| DIB2 pD | 81.5 | 83.1 | 82.3 | 80.6 |
| DIB3 pA | 83.1 | 84.0 | 84.0 | 81.3 |
| DIB3 pB | 80.4 | 84.0 | 81.0 | 79.0 |
| DIB3 pC | 84.0 | 84.7 | 83.9 | 81.0 |
| DIB3 pD | 87.1 | 87.6 | 87.7 | 87.1 |
| * | Measured later in the day. See below. | |||
Issues:
- DIB1 pB showed a low-amplitude triangle wave even at the lowest temperature, and did not change as it was heated through transition. Later we discovered that you had to de-select connecting the test signal to this QET on this DIB in order to see the triangle wave properly.
- Italicized values may be inaccurate - there were interruptions due to railing or GUI crashes that made us miss the precise time of the transition.
| 1216 | After performing Tc measurements, DIB1 pB is still showing a small triangle wave (~16mVpp) compared to the other channels, which showed ~160mVpp. Inspect the modulation curve, but everything looks on the up and up there. Trying to turn off the test signal on pB requires not only the disconnecting of the test signal from that specific channel, but also the entire disabling of the Signal Generator for DCRC1. This finally gets the small triangle wave to stop appearing on DIB1 pB. Applying a QET bias produces pulses as expected, so it seems like pB is functioning properly in that respect. Unpower DCRC1 to see if the behavior persists after a power cycle. |
|---|---|
| 1355 | Repower DCRC1, zap SQUIDs. |
| 1420 | Relock DCRC1 pB's SQUID to get a higher modulation depth. SQUID Bias and Lockpoint were -76uA and -2.04mV, respectively. Now they are set to -86.8uA and -3.29mV, respectively. After investigating pB's behavior, Enabling the Signal Generator causes a ~20mVpp triangle wave to appear on pB and no other channels. Connecting the Test Signal to the other channels produces a ~100-~200mVpp triangle wave on pA, pC, or pD, though connecting the test signal to pB decreases the size of the triangle wave that was already on pB to ~1mVpp. Disconnecting the Test Signal increases the size of the pB triangle wave back to ~20mVpp, and the only way to eliminate this wave is to Disable the Signal Generator for DCRC1 entirely. |
| 1430 | Notice some low-frequency noise on all channels on DCRC1. Unpower DCRCs and let it sit. |
| 1530 | Repower DCRC1. Zap SQUIDs. |
| 1535 | Noise still present on DCRC1 pC (~350Hz noise). Though it's not visible on the other channels currently, so it might be better-ish. |
| 1600 | While heating the fridge to attempt to measure DCRC1 pB's Tc's by having the Signal Generator “disabled” on DCRC1, all of a sudden the temperature spiked to ~120mK despite only applying 16mW to the MC Heater. After checking the phonon channels, all of DIB3's phonon channels and charge channels are showing extremely large white-noise bands (~6Vpp on Qi/Qo (not mVpp… Vpp) and ~1.5Vpp on the phonon channels). This is most likely what's heating the fridge, though it's unclear what brought DCRC3 into this state. It is not the test signal, power cycling/heating the FETs on DIB3 does not remove the gigantic white noise. |
| 1610 | During troubleshooting, it was also witnessed that the SQUID Tuning GUI again changed the values of one channel on DIB3 to duplicate values of another channel on DIB3. This occurred after editing the values of pA, closing the Editing Dialog, changing the channel dropdown to pB, then opening the Editing Dialog. The values listed for SQUID Bias and Lockpoint and Driver Offset in the Editing Dialog were the same that had been entered for pA, and they were different from those listed for pB before the Editing Dialog had been opened. This occurred a few more times with various DIB3 channels when attempting to resurrect the DIB3 channels with the huge white noise. |
| 1622 | The width of the white noise appeared related to the Feedback Gain, though even when set to 1 or 0, the white noise was still far more than usual. Repower DCRC3. |
| 1640 | The noise has gone away, and after unrailing some channels by adjusting the Driver Offsets, we should be good to go. |
| 1645 | Commence LHe transfer (30.8%). |
| 1647 | Begin heating mixing chamber to attempt to find DIB1 pB's Tc. |
| 1650 | Fill LN2 cold trap full. |
| 1712 | Finish measuring DIB1 pB's Tc. Results added to above table. Turn off Mixing Chamber heater. |
| 1715 | Cease LHe transfer (76.6%). |
Spreadsheet of Mini-IbIs data