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2010/12/15

1406 Raised Dewar after re-tightening all the In seals.
1407 Leak checker He BG 2.9E-10cc/s
IVC BG with pumping station connected: 8.5E-9cc/s
IVC BG without pumping station 1.2E-7cc/s. BG is too high. Will flush IVC with N2
1421 Fill IVC to 100mbar N2 and pump it out
1424 Pump to 0.1mbar, He 1.5E-6cc/s
1425 Fill IVC to 100mbar and pump it out
1428 Pump to 0.1mbar, He 5E-7cc/s
1429 Fill IVC to 100mbar N2 and pump it out
1432 Pump to 0.1mbar, He 1.2E-7cc/s
1433 Fill IVC to 100mbar N2 and pump it out
1437 Pump to 0.1mbar, He 1E-7cc/s. Stop flushing and connect the pumping station.
1710 IVC BG 8.8E-8cc/s with pumping station isolated
Fill N2 cold trap full
The leak rate rose again when pumping the main bath. The leak is still there. We decided to go to 77K anyway.

1745 Fill main bath with He gas. IVC He level didn't change.
1758 No Leak found at BG level 9E-8cc/s. The leak went away. It could be a virtual leak.

Evacuate and isolate 1K pot
Put in 3.4mbar N2 change gas in the hose and 0.46mbar in the IVC.
1809 Remove He recovery hose and start to transfer liquid N2
2118 The fridge is full. Resistor plateaus at 1312Ohm