2022/03/25 (Friday)
- Lab in-personnel: Anthony, Kitty, Megan, Matt
| Status | Run 76 in progress |
|---|---|
| Setup | Cable 2/1/3 → diverter/nothing/nothing → DCRC 1/3/4 |
| 1125 | MC/Coldplate = 28.4/140 mK, Still = 1.14 K / 0.130 mbar / 0 mW, G1/G2= 163/164 mbar, 1K Pot = 18° / 1.66 K / 30±2 mbar. MB = 31.1%. |
| 1125 | Goldman = 76.1 mK @ 632 uV excitation |
| 1135 | Check phonon channels. As before, DCRC3 and DCRC4 channels are showing good pulses, but none of the DCRC1 channels are showing pulses. |
| 1215 | Fill LN2 cold trap bath |
| 1225 | Performed a quick IbIs on all the DCRC1 channels, scanning from QETbias = 900 uA down to 100 uA in steps of 100. pA: linear decrease above 400, flat below 400. The linear part implies 320 mOhm (which makes no sense) pB: Linear decrease below 400, flat above 400 (that flatness is a familiar issue with this channel). Implied R = 140 mOhm pC: linear decrease throughout with one SQUID jump. Implied R = 180-190 mOhm. pD: linear decrease throughout with one SQUID jump. Implied R = 270 mOhm. So, none of this makes sense. Seems like DCRC1 has problems. |
| 1240 | Turn off DAQ programs and unplug DCRC1. |
| 1345 | MC temperature settles significantly lower with DCRC1 off, 28.4→27.4 mK |
| 1415 | Try DCRC32(5) on Cable 2 instead of DCRC55(1). Start MIDAS and DAQ programs with only DCRC5 enabled. Zap SQUIDs. MC temperature initially increases to 140 mK then falls. It rises when 15V power is off, so leaving it on. |
| 1425 | Fridge is still warmer than the Tc's but let's try looking at phonon channels. All 4 show traces. At first they seem unresponsive to changes in QET biases, or switching from non-inverting to open. But then it turns out that this is only when the driver gain is 1 - at higher settings they are responsive… |
| 1435 | Try some IbIs on pD with driver gain 2 - it makes no sense, baseline rises with bias rather than falling. And it's clearly not in transition, temperature and QET bias are too high. |
| 1445 | MC temperature settles at 52 mK, clearly this DCRC is also having problems. |
| 1450 | Turn off DAQ programs and unplug DCRC5. |
| 1514 | Begin LHe transfer @ MB = 25.0% |
| 1552 | End LHe transfer @ MB = 94.1% |
| 1650 | Restart DAQ programs with only DCRCs 3&4 enabled. Pulses look great. |
| 1655 | MC = 27.1 mK, quite low. |