2012/05/02

Attendees: Chagani, Mandic, Monin, Radpour, Zhang.

1. Install third stripline.
   • Radpour will check stripline for continuity.
   • Copper baffles should be fine for 3 striplines, perhaps not for six.
   • Should have enough spacers. If more are required, design is simple so fabrication can be done without need to submit job to mechanical workshop.
   • Require screws and nuts to sandwich striplines and spacers: M1 x 5 mm, stainless steel. Chagani to purchase.
   • Remove striplines from fridge, install third stripline on bench, place assembled structure back in fridge.
2. Install additional thermometers.
   • There are plenty of wires running into the fridge. However, all wires run to the mixing chamber.
   • No real need for this at the moment.
   • Defer to future.
3. Spacer between insert flange and top of cryostat.
   • Potential to buy a few more inches.
   • Should wait until tower design and tests facility priorities are issued before embarking on this.
   • Defer to future.
4. Replace 600 mK rod with can.
   • Single contact point with tower may be reason for elevated base temperature.
   • Must enlarge top of IVC to accommodate this, therefore moving 1 K pot line.
   • Defer to future.
   • Possible temporary solutions are to run copper cables from still, down 600 mK rod and onto opposite side of tower, or punch holes in rod and fasten copper cables to it.
   • 600 mK spool at base of tower comes very close to 4 K stage. May wish to extend this. Monin to investigate.

1. Leak check mixing chamber lines.
   • Have leak checked lines in the past, but helium background leak rate >1E-6 mbar l/s.
   • Have large air leak somewhere outside fridge.
   • Pump mixture into dump, seal it off, and cryopump remaining mixture into storage.
   • Pump out mixing chamber lines for a few days to reduce helium background leak rate.
   • Leak check section-by-section: Chagani & Radpour.
2. Check, uninstall and polish temperature stages.
   • All four indium seals will need to be removed. Ensure we have enough indium to replace them. Radpour to submit indium for recycling.
   • Check 600 mK rod is fastened tightly to top of fridge: may give us an indication of cause of elevated base temperature if lose.
   • Check for contact between 600 mK rod and other temperature stages.
   • Codoreanu to write-up run-by-run temperatures of stages.
   • Start taking temperatures of stages during run: see “Laboratory Checklist” below.
3. Bring mixing chamber RuO2 thermometer back online.
   • Works at room temperature. Suspected loose connection. Should be easy to fix.
4. Change oil in He-3 & He-4 pumps.
   • Loss of He-4 pump oil during a previous run means this opportunity should be taken to drain and replace it.
   • He-3 pump oil slightly discoloured, but is probably fine. Can wait until move to new building to drain and replace it.
   • Obtain torque spanner from mechanical workshop. Chagani to enquire.
5. Leaky IVC bottom flange.
   • Could re-machine both flanges.
   • Perhaps profiles could be obtained for both flanges.
   • Chagani to talk to mechanical workshop.
6. Fault with pressure sensor.
   • Pfeiffer cold cathode pressure sensor does not switch to low pressure gauge.
   • Could be contamination, but cleaning is difficult: no heating element, so sensor must be striped apart and cleaned with alcohol.
   • Chagani to talk to Pfeiffer first.

1. Chagani (full-time).
   • Maintenance & upgrade.
   • Flexible side coax tests: EDELWEISS cable; niobium wires.
   • 100 mm crystal tests: G101b; 100 mm iZIP.
2. Radpour (full-time).
   • Maintenance & upgrade.
   • Learn DAQ: currently journeyman.
   • Fridge procedure manual.
   • 100 mm crystal tests: G101b; 100 mm iZIP.
   • Help with Little Blue upgrade/runs.
3. Monin (full-time).
   • Learn K100 installation procedure: currently novice.
   • Learn K100 cooldown procedure: currently novice.
   • Learn DAQ: currently novice.
   • Learn analysis: currently novice.
   • 100 mm crystal tests: G101b; 100 mm iZIP.
4. Strandberg (full-time).
   • Learn K100 cooldown procedure: currently journeyman.
   • Flexible side coax tests: EDELWEISS cable; niobium wires.
   • Help with Little Blue upgrade/runs.
   • Gamma shield.
5. Codoreanu (3/4-time).
   • Learn K100 cooldown procedure: currently novice.
   • Learn DAQ: currently novice.
   • Learn analysis: currently novice.
   • 100 mm crystal tests: G101b; 100 mm iZIP.
   • Gamma shield.
6. Zhang
   • Maintenance & upgrade.
   • Time permitting, 100 mm crystal tests: G101b; 100 mm iZIP.
7. Kennedy
   • K100 simulation?
   • Gamma spectrometer?

1. Run 28: Flexible side coax test with Gary's cable.
2. Run 29: G101b.
3. Perform maintenance.
4. Run 30: Maintenance run.
   • Time permitting, it would be useful to have empty run.
   • Can fasten tower thermometer to 30 mK stage and/or use mixing chamber thermometer.
   • IR should not be a problem.
5. Run 31: 100 mm iZIP.
   • Is new source plate required? Chagani to check.
   • Will new beta source be available in time? Probably not, but would be useful for future runs. Chagani to chase up.
   • New adapter plate for 3 side coaxes: Chagani & Zhang.
   • Require SQUET card and position 1 side coax: Chagani to chase up.
   • Require extra SCUHBA extender plug: Chagani to chase up.
   • Require third stripline: Chagani, Radpour & Zhang to install.
   • Require third DCRCv3 board: Chagani to chase up.
   • Require faster switch: Chagani to chase up.
   • Gamma shield should be ready in time: Codoreanu & Strandberg to chase this up with mechanical workshop.

1. Radpour to prepare paper version, Monin to conduct checks and build online database.
2. Daily:
   • N2 purge cabinet flow rate.
3. Weekly:
   • Pressure in helium and nitrogen cylinders.
   • Number of spare cylinders.
4. K100 run checklist:
   • N2 cold trap level: should be filled twice per day.
   • Temperature of stages.
   • Helium liquid level.
   • 1 K pot temperature and pressure.
   • Pressure in P1, G1 & G2, and overnight variation.
   • Base temperature and overnight variation.
   • Pressure in and temperature of dump at start and end of run.