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2012/12/18

0205 Fill N2 cold trap full.
0245 IVC pressure 8.6E-7 mbar. Background helium leak rate 2.2E-9 mbar l/s. Start blowing nitrogen out of main bath.
0410 Nitrogen blown out of main bath. Helium leak rate rose to 1.2E-8 mbar l/s, but rate of increase consistent with that expected from background: no gross leak.
0440 Evacuate main bath and overpressurise with helium gas. Background helium leak rate 2.1E-8 mbar l/s. Leak rate remains unchanged when main bath overpressurised.
Isolate leak checker and evacuate IVC with turbo pump.
0510 Mixing chamber tempreature 78.5 K. Electrical check shows no problems apart from 20 nS conductivity in reverse direction for LED 2 on DIB 3.
0842 Filled LN2 cold trap.
0950 Fed Cricket 4 pellets. Bye guys!
1010 Bye Allison! Pump mixture into dump in preparation for throughput test.
Evacuate main bath as precaution - probably unnecessary.
1110 Pressure in IVC 6.3E-7 mbar. Open valve to leak checker and isolate turbo pump. Background helium leak rate 3.5E-9 mbar l/s. Open gate valve condenser line speedivalve to facilitate throughput test: 45 mbar/min; fine. No change in helium leak rate. Pump mixture to dump.
Background helium leak rate 3.6E-9 mbar l/s. Overpressurise main bath with helium gas. No change in helium leak rate.
Isolate leak checker and evacuate IVC with turbo pump.
1137 Pressure in IVC: 8.6E-7 mbar.
Filled IVC with 4E-2 mbar of He exchange gas.
1200 Started LHe transfer.
1826 Pump out He exchange gas just under 10 K.
2104 Apply external He gas pressure to dewar.
2145 End LHe transfer (91.3%).
2159 Filled LN2 cold trap.
Closed gate and condenser valve.
Restart cryocleaning mixture.