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2015/10/19 (Monday)

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Current setup: iZIP mode, DIB1/2/3 → cables → 3.2 MHz filters → DCRC55/33/50.
Overnight: Taking background data. Tower temp stable.
0925 Main bath = 1.6%. Yikes. I wondered whether leaving the transfer tube in the cryostat might make the bath boil off more quickly - had no idea it would have this dramatic an effect.
Top of fridge is quite frosty. Transfer tube must be transferring a lot of heat. Could be partially due to fluid oscillations in the tube.
0930 1K Pot temp/press started falling at about 7:30, now 1.64 K / 9/0 mbar.
0937 Start transfer at 0.1%
1055 End LHe transfer at 70.5%.
This time at the end we of course removed the cryostat section of the transfer tube.
we used a longer (and thicker) extension tube on the Dewar-section of the transfer tube, and I think it probably didn't form a proper seal at the joint. So this is probably why we could not transfer to higher than 70.5% even though we had a full Dewar. Weighing the Dewar after transfer revealed that there are still 45 L left in it. So we should not use the longer/thicker extension.

Transfer procedure with Goldman transfer tube:

  1. Unscrew cap from cryostat-section of transfer tube
  2. Insert cryostat-section into cryostat port all the way, screw down o-ring connector onto port
  3. Screw cap onto cryostat-section. (Starting with it open allows He to purge the air out of the tube.)
  4. Make sure that Dewar-section has thin extender tube screwed tightly to the end and has two knurled brass connectors somewhere in the middle of the tube. Also it should have a paper binder clip.
  5. Remove knurled knob from top of Dewar. Close blue and red Dewar valves.
  6. Open yellow Dewar valve (top port) and lower Dewar-section of transfer tube into Dewar. This can be done by one person with the upper section resting on the top of the cryostat. Lower it until gas starts coming through or until it is close to the bottom, whichever comes first, and screw knurled knob onto Dewar port.
  7. He gas should start coming out of the end of the Dewar-section faster and faster. If the Dewar is half empty you may need to accelerate the process by applying He pressure to the Dewar from the wall supply through the side port (blue valve).
  8. When a plume comes out of the end of the Dewar-section, quickly unscrew the cap on the cryostat-section, insert the Dewar-section end into the cryostat-section, and quickly screw the connection tight.
  9. Update log book with time, bath level, recovery meter reading, amount in Dewar (if known)
  10. At this point the procedure is the same as with the old tube: lower tube into Dewar until it is 2 inches from bottom, apply pressure from wall supply, throttle pressure with blue valve on Dewar to maintain an approximate fill rate of 1%/minute.
  11. Wait until the bath reaches 90% or when it stops rising (because Dewar is nearly empty)
  12. Stop pressurizing Dewar. Let pressure out through red valve.
  13. Pull Dewar-section up so that the bottom is well above the level in the Dewar
  14. Disconnect the two sections then screw the cap onto the cryostat-section
  15. Pull Dewar section completely out of Dewar and close yellow valve on top port
  16. Update log book with time, bath level, recovery meter reading, amount in Dewar (if known)
  17. Remove cryostat-section from cryostat and plug port with stopper. (Probably it is best to unscrew cap before removal.)
  18. If Dewar is not empty reconnect side port to recovery (through blue valve). Close other two valves.
  19. If Dewar mostly empty weigh it and return it to recovery station in the hall
1110 Looking at phonon channels, all are showing pulses. Set new phonon thresholds.
A B C D
DIB1 36 40 42 40
DIB2 24 18 20 28
DIB3 40 46 58 48
1150 Set up MultiDAQ files for a Qbias sweep of background data.
1200 Start Qbias sweep background data 4 cycles of 15 minute series, FG=5/2/5, OG=3, with 1000 initial randoms, 2000 events/file, 30s flash and 25min cooldown in between. The Qbias was swept in the following order: +/-2V, +/-4V, +/-6V, +/-8V, 0V, -/+6V, -/+8V.
1217 During a flash and cooldown, fill LN2 cold trap full.
1650 After the first cycle of data had finished taking, stop DAQDAQ to modify the Run Duration. We've decided on 30min runs instead of 15 minutes.
1710 Start Qbias sweep background data 2 cycles of 30 minute series, FG=5/2/5, OG=3, with 1000 initial randoms, 2000 events/file, 30s flash and 25min cooldown in between. The Qbias was swept in the following order: +/-2V, +/-4V, +/-6V, +/-8V, 0V, -/+6V, -/+8V.
1802 Fill LN2 cold trap full.

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