| 0837 | MC/Tower = 24.9/32.7 mK. G1/G2 = 153/153 mbar, Still = 1.04 K / 0.10 mbar, 1K Pot = 1.72 K / 24.0 mbar. Cold plate = 134 mK. MB = 26.8%. |
| 0851 | Fill LN trap Dewar. |
Cooling power test (monitoring both MC(H35) and Tower(U02844) temperatures):
| MC P (μW) | MC T (mK) | Tower T (mK) |
| 0 | 26.1 | 34 |
| 10 | 47.9 | 52 |
| 20 | 64.7 | 68 |
| 40 | 79 | 80.5 |
| 60 | 89.5 | 92 |
| 100 | 109 | 109 |
| 140 | 118 | 120 |
The still heat was set to optimize the base: 0 mW for MC < 50 mK, 5 mW for 50 mK < MC < 90 mK, 10 mW for MC > 90 mK.
| 1324 | Plug DCRC31/33/50 into DIB1/2/3. Power FETs. Tower remains at 33 mK. |
| 1341 | Zap all SQUIDs. Tower increases to about 35 mK during zaps. |
Problem with DIB1 pA: we tried to set the SQUID bias and lock points, but increasing the bias caused only small changes in the observed waveform. This SQUID showed problems during electrical checkouts as well: Bias to Return was OK at room temperature, about 3X too high at LN temperature, and around 1000X too high at LHe temperature. We hoped this was just a spurious problem with the cable to the breakout box, because some odd values were seen on other SQUID channels earlier that went away with an unplug/replug. But it seems it's a real problem with the channel somehow. It may be difficult to track down where if it is only seen at cold temperatures. Update: this SQUID channel reappeared on June 11. If it's an intermittent problem it will be even harder to track down. We need to remember to check this channel when we are warm and move the stripline around to see if one of the traces is almost broken.
| 1530 | Finish finding SQUID settings. |
| DIB1 DCRC31 SQUID Settings |
| Channel | Bias (mA) | Lockpoint (mV) | Vpp |
| A | 86.09 | 6.03 | 0.488 |
| B | 80.00 | 6.42 | 0.428 |
| C | 82.04 | 4.18 | 0.461 |
| D | 83.99* | 3.12* | 468* |
*When changing the SQUID bias, the baseline changed but it did not produce the expected modulation curve, thus no SQUID settings were obtained for channel D on DIB 1. Update: this SQUID channel reappeared on June 11, and SQUID settings were determined.
| DIB2 DCRC33 SQUID Settings |
| Channel | Bias (mA) | Lockpoint (mV) | Vpp |
| A | 78.23 | 5.25 | 0.438 |
| B | 66.41 | 3.02 | 0.359 |
| C | 84.00 | 3.50 | 0.446 |
| D | 83.99 | 3.02 | 0.495 |
| DIB3 DCRC50 SQUID Settings |
| Channel | Bias (mA) | Lockpoint (mV) | Vpp |
| A | -83.91 | -4.67 | 0.332 |
| B | -85.58 | -2.82 | 0.365 |
| C | -72.00 | -1.95 | 0.345 |
| D | -87.86 | -2.53 | 0.354 |
| 1700 | Problem with transfer tube. It got very frosty when we started transfer, even though the vacuum jacket was pumped out recently. We ceased the transfer and pumped on the jacket with the leak detector. We found a large leak where the tube that goes into the cryostat meets the larger diameter curved part before the bellows. As a temporary fix we smeared this region with vacuum grease, which allowed us to pump it out to a much lower level. Then we began a transfer. |
| 1720 | Begin LHe transfer at 11.5%. |
| 1727 | Start flashing detector overnight. Tower temp increases to 290 mK, MC to 106 mK. |
| 1812 | Finish transfer at 91.5%. |
| 1824 | Fill LN cold trap Dewar. |