2020/03/07 (Saturday)
| Setup | Run 72. DIB 1/3/4 → Stripline 43/41/48 → Cable 3/2/1 → nothing/nothing/accessory_interposer → HV_Conn 1/3/2 → HV 1/2 → DCRCX(4)/DCRC55(1). DCRCs off overnight. Lead/poly shield erected (4 lead walls, 2 poly walls). |
|---|---|
| 0550 | Tower = 68.0 mK. Try reducing Still heater 8→4 mW. Tower rises to 74 mK. Put heater back to 8 mW. Tower falls back to 67.8 mK. |
| 0855 | Increase Still heater 8→10 mW. Tower falls to 59 mK. But then starts slowly rising. |
| 1130 | Tower/MC/Coldplate = 62.4/47.5/193 mK, Still = 1.55±0.15 K / 0.240 mbar / 10 mW, G1/G2= 603/553 mbar, 1K Pot = 2.28 K / 26 mbar. MB = 30.0% |
| 1144 | Start LHe transfer @ MB = 29.6% |
| 1150 | Fill LN2 cold trap bath |
| 1200 | HV test: disconnect Cable 1 at Ebox, everything else is connected, DCRC1/4 powered down. Vary HV with DCRC2, read HV at the supply, and measure HV between cable pins 1 (QETA Return 1, which is used for HV) and 36 (QETD Return 1, which is one of the readout channels so is grounded by the DCRC). |
| HV at supply [V] | Fluke 87V reading at Ebox [V] | Vtest [V] | Vtest [V] with Fluke disconnected | Supply/Ebox |
|---|---|---|---|---|
| 0.0004 | 0.0 | |||
| -9.52 | -0.233 | 40.8583691 | ||
| -22.02 | -0.539 | 40.85343228 | ||
| -48.00 | -1.174 | 40.88586031 | ||
| -108.8 | -2.665 | 40.82551595 | ||
| -152.4 | -3.731 | -0.336 | 40.84695792 | |
| 65.39 | 1.598 | 0.144 | drops below 1.4mV | 40.91989987 |
| 108.9 | 2.668 | 0.240 | 40.81709145 | |
| 152.4 | 3.733 | 0.336 | drops below 3.0mV | 40.82507367 |
| Average: | 40.85402507 | |||
| STD DEV: | 0.032475346 | |||
This is consistent if we assume the Fluke multimeter has an internal resistance of around 10 MOhm. Then the Supply/Ebox ratio should be 441/10 = 44.1, pretty close. The measured Vtest with the Fluke connected imply a total resistance of 454 MOhm; subtracting the 441 MOhm of the HV box circuit gives 13 MOhm for the Fluke resistance, again pretty close. Conclusion is that it looks like we are getting the correct voltage at the ebox.
| 1217 | End LHe transfer at 90.7% |
|---|---|
| 1245 | Plug DCRC1/4 back in as normal, turn off DAQ programs, reset ODB to enable these and make DCRC1 master, others slaves. Turn DAQ programs back on. |
| 1250 | Zap SQUIDS for DCRCs 1&4 |
| 1300 | Check phonon channels, they look OK after adjusting driver offsets. But weak pulses as expected because it's warm, >75 mK |
| 1300 | 1K Pot is a little cooler after the transfer Try opening 1K Pot needle valve wider, 45°→50°. 26→30 mbar, 2.213→2.235 K |
| 1305 | open 1K Pot needle valve wider, 50°→60°. 30→34 mbar, 2.235→2.251 K |
| 1325 | Tower = 71.9 mK. Hopefully it will keep cooling (though it looks like it's settling now). G1/G2 = 588/539 mbar. Maybe will try increasing Still heat more later today. |