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2013/11/21

0345 Seal up and begin pumping on IVC with rough pump.
0600 IVC pressure 5.4E-4 m bar. Open line to leak checker and isolate turbo pump. Background helium leak rate 1.5E-7 mbar l/s. Evacuate main bath and overpressurise with He-4 gas. Helium leak rate decreased to 1.4E-7 mbar l/s.
Fill N2 cold trap full.
0615 Evacuate 1 K pot.
Add 1 mbar He-4 exchange gas to IVC. Commence nitrogen transfer.
0810 Cease nitrogen transfer. Mixing chamber temperature 140 K and falling, IVC pressure 0.46 mbar.
1105 Mixing chamber temperature 82 K. Start evacuating IVC.
1340 IVC pressure 2.5E-6 mbar.
1347 Fill LN2 cold trap full.
1400 With mixing chamber temperature of 81.5 K commence Nitrogen blowout. Simultaneously commence leak check with background leak rate of 2.4E-7 mbar*l/s and IVC pressure of 2.2E-5 mbar.
1505 End Nitrogen blow out. Leak rate dropped consistently during course of transfer, ending with 1.4E-7 mbar*l/s. There is no indication of a leak. Mixing chamber temperature at 81.2 K and IVC pressure of 3.5E-5 mbar.
1510 Begin pumping on 1K Pot and evacuating main bath.
1530 Start leak check with background leak rate at 1.3E-7 mbar*l/s. Begin filling main bath with He exchange gas.
1541 Main bath filled with exchange gas, leak rate held at 1.2E-7 mbar*l/s. As before, no sign of leak.
Switch to turbo pump and turn off leak checker.
1605 Add 40 μbar He exchange gas.
1620 Commence LHe transfer (0.0%).
1920 End LHe transfer (95.0%).
2100 With IVC pressure of 6.3E-3 mbar and mixing chamber temperature of 10.9 K, commence pumping out IVC exchange gas with Turbo pump.