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2017/06/27 (Tuesday)

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Status Main bath is up, IVC pumping overnight. Small leak at top of stripline tube. Mixture has been cryocleaned 7 times. Fridge is evacuated but should probably be pumped out again. 1K Pot needle valve is open, so now there will be air in the pot, should pump it out before cooling. Cryostat vacuum jacket has been pumped down to 190 ubar; we're assuming this is adequate.
0845 Lab = 22.6 C, 32% humidity.
0845 Turbo = 74 nbar, IVC = 4.0 μbar
0900 Open LN2 Trap 1 (room temperature) up to G1. 5.5 mbar, after Friday's 140 min. cryocleaning. Pump out trap with scroll pump. Then return trap to LN2 bath.
Cryocleaning log
date duration (minutes) contaminants removed (mbar) notes
June 15 125 54 may not have had flow the entire time
June 15 70 45.3
June 15 75 24.3
June 22 80 65.9 before this cleaning we pumped the fridge lines and condenser return line to the dump
June 23 90 11.1 it seemed to be at room temperature (let it warm up for 2 hr 50 min)
June 23 110 11.1
June 26 105 5.5
0910 Close 1K Pot needle valve, then pump out 1K Pot with scroll pump
0915 Check fridge lines for any pressure, not much. Pump out fridge lines with scroll pump.
0925 LD on IVC, signal falls to 3.0 pbarL/s after about 10 minutes
1055 LD = 2.5 pbarL/s, IVC bkg
1100 Begin pumping out main bath with scroll pump. P2 falls below 100 mbar quickly, and below 1 mbar after about 5 minutes.
1110 Pressurize MB with He gas to 130 mbar above 1atm on G3. LD signal rises to 40 pbarL/s, a little worse than Run 62.
1120 Let 4.6 mbar He exchange gas into IVC
1130 Begin transferring LN2 to main bath.
MC(Cernox) = 297.4 K, Sorb = >249 K (max), IVC = 4.6 mbar.
We'll monitor the leakage from QETs to chassis, hope to see it get less leaky.
1135 MC(Cernox) = 296.5 K, Sorb = >249 K (max), IVC = 4.6 mbar, Level resistor = 1.06 kΩ. DIB4 QETA to Chassis = 165 Ω.
1150 MC(Cernox) = 282.7 K, Sorb = >249 K (max), IVC = 4.0 mbar, Level resistor = 1.126 kΩ. DIB4 QETA to Chassis = 163 Ω.
1205 MC(Cernox) = 252.5 K, Sorb = >249 K (max), IVC = 2.5 mbar, Level resistor = 1.234 kΩ. DIB4 QETA to Chassis = 174 Ω.
1230 MC(Cernox) = 190.1 K, Sorb = 225 K, IVC = 2.2 mbar, Level resistor = 1.343 kΩ. DIB4 QETA to Chassis = 582 Ω.
1235 Stopping transfer.
1245 MC(Cernox) = 165.5 K, Sorb = 185.3 K, IVC = 1.9 mbar. DIB4 QETA to Chassis = 4.11 kΩ.
1250 DIB4 QETA to Chassis = 8 kΩ. Check interchannel: A-B (same side) = 5 kΩ, A-D (opp sides) = 39 kΩ
1255 MC(Cernox) = 153.8 K, Sorb = 168.0 K, IVC = 1.9 mbar. DIB4 QETA to Chassis = 28.5 kΩ.
1300 DIB4 QETA to Chassis = 36 kΩ. Check interchannel: A-B (same side) = 22 kΩ, A-D (opp sides) = 316 kΩ
1307 MC(Cernox) = 141.2 K, Sorb = 152.6 K, IVC = 1.9 mbar. DIB4 QETA to Chassis = 180.5 kΩ.
1325 MC(Cernox) = 127.0 K, Sorb = 139.4 K, IVC = 1.6 mbar. DIB4 QETA to Chassis = 326.5 kΩ.
1330 DIB4 QETA to Chassis = 335 kΩ. Check interchannel: A-B (same side) = 215 kΩ, A-D (opp sides) = 3.7 nS
1345 MC(Cernox) = 114.8 K, Sorb = 131.3 K, IVC = 1.6 mbar. DIB4 QETA to Chassis = 427.6 kΩ.
DIB4 QETA to Chassis = 441 kΩ, QETD to Chassis = 7 nS, A-D (opp sides) = 3.9 nS, A-B (same side) = 300 kΩ
so it looks like the leakage is close to the Side 2 surface, or from a Side 2 channel, because leakage to chassis is a lot higher on that side.
1415 MC(Cernox) = 101.3 K, Sorb = 125.3 K, IVC = 1.6 mbar. DIB4 QETA to Chassis = 544.8 kΩ.
1500 MC(Cernox) = 89.1 K, Sorb = 121.7 K, IVC = 1.4 mbar. DIB4 QETA to Chassis = 642 kΩ.
1550 MC(Cernox) = 82.4 K, Sorb = 120.4 K, IVC = 1.4 mbar. DIB4 QETA to Chassis = 694 kΩ.
Throughput test procedure, Cold Trap 2:
  1. All mixture in dump, LN2 traps cold, condenser & still valves open (3He pump on - optional)
  2. Open V9, V13b, V12b+speedivalve, V3. Wait for G1 to be close to G2.
  3. Close V12b+speedivalve and V3, open V1
  4. monitor G1
1600 Perform throughput test @ 81 K. G1 reaches maximum of 610 mbar before isolating mix in still, then falls to minimum of 35 mbar after opening G1 to condenser. Now stuck - no throughput. Gah. Throughput < 0.2 mbar/min. In Run 62 after we finally got it working it was 45 mbar/min.
1615 Pump mixture back to dump
1620 MC(Cernox) =80.1 K, Sorb = 120.1 K, IVC = 1.4 mbar. DIB4 QETA to Chassis = 707 kΩ.
1630 Start pumping out IVC so we can do a leak check during blowout tomorrow. (MC temp stops decreasing.)

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