| 0910 | Pump out N2 exchange gas. Pressure reads: 4E-3 mbar. |
| 0930 | Fill LN2 cold trap. |
| | It's undetermined still whether the gauge or the pump itself isn't working. If there was a leak, we should be reading a lower pressure at 77 K. Maybe we'll try Little Blue's pump on a hose to see if it does something different or if their gauge reads differently. |
| 1202 | Plugged in Little Blue's pressure gauge. Reads: 6E-5 torr = 8E-5 mbar for IVC. Our gauge still reads 4E-3 mbar. Will close off IVC to see how pressure readings change. |
| 1213 | IVC isolated - LB gauge: 6E-5 torr. Closing off turbo pump. Pressure in hose leading to IVC (still isolated) –> our gauge: 4.6E-3 mbar. LB gauge: 3E-4 torr = 4E-4 mbar. |
| 1227 | Under the same conditions as above –> our gauge: 8.6E-3 mbar. LB gauge: 10E-3 torr = 1.3E-3 mbar. This is concerning since the turbo and IVC are both isolated from the pressure gauges. |
| 1231 | Right before opening line to turbo pump again, pressure on pump from our gauge had increased to 10E-2 mbar. |
| 1233 | Okay, tightened further the connection between LB's gauge and the pumping manifold. Perhaps this seal wasn't tight enough. Will redo above tests. |
| 1243 | IVC sealed off. Turbo pumping on line. Our gauge: 4E-3 mbar. LB gauge: 1E-5 torr = 1.3E-5 mbar. |
| | Two concerns: 1) if LB gauge IS correct, why isn't the pressure lower (esp. with IVC isolated)? ; 2) Why is there a big discrepancy between our gauge and LB's? |
| | Seems like a double whammy of misfortune if both pump and gauge are not working correctly. |
| 1251 | LB gauge: 1E-5 mbar. |
| 1309 | LB gauge: 8.7E-6 mbar. |
| 1342 | Background leak rate: 2.6E-10 mbar l/s |
| 1343 | Leak rate with line open to IVC and turbo pump on: 2.9E-10 mbar l/s; LB gauge: 7E-6 torr; ours: 4E-3 mbar |
| | Pump seems okay. Can't use our gauge for high vacuum, but perhaps can use it for monitoring entry of exchange gas. |
| 1349 | Background leak rate with turbo pump off: 3.1E-9 mbar l/s. Giving the turbo pump a rest since it's been going non-stop for a couple of days. |
| 1419 | Begin blow-out of LN2. |
| 1540 | End blow-out of LN2. No leak detected (4.8E-9 mbar l/s). |
| 1730 | Apparently there was a bit of LN2 left in the dewar. The pressure in P2 is ~ 3.4 mbar. |
| | Throughput test results: 1) 35 mbar/ min; 2) 40 mbar/ min. |
| 1856 | Re-blew out LN2. The helium tank had run out of gas, making it seem as if the initial blow-out was complete. |
| 1934 | P2=3.8mbar. It took too long to pump the bath dry. There is likely liquid left. I'll fill the bath with He gas and let it warm up over night. |
| 1956 | Filled bath with He gas. Inserted N2 transfer stick with the rubber hose hooked up into the transfer port to let the gas escape while warming up. Closed IVC and turned off leakchecker and cold cathode gauge. MC X12004 75.59K. |
| 2012 | Filled N2 cold trap. |
| 2052 | Clean the mixture overnight. |