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  • Lab Update
    • A short at the FET gate for the center channel is producing excessive noise
      • this short was 12 nS at the 77K checkout, and seems to have made this channel a little noisier than the others
      • recently it rose to 25 nS, suggesting a very low resistance from gate to chassis, and the noise became terrible
      • jostling the fridge improved it somewhat, making a short caused by contact at the SQUET seem likely. We can take data at this noise level but the 60keV resolution is bad.
      • we did a partial warmup and cooldown, but couldn't get below 0.38 K. So the jostling may have also caused a thermal touch.
      • Warming now - we'll open the fridge and try to fix both problems.
    • Before warming up, I tried the source mover to make sure it works. Did a couple of short moves and saw heating similar to the last run. I think this suggests that our theory that the warming was due resistance at the connection near the coils is wrong.
  • General Updates