| 1132 | Pressure in IVC: 4E-4 mbar. |
| 1137 | Open leak checker to IVC; isolated turbo pump. |
| 1150 | Background leak rate of IVC is 6E-9 mbar l/s. |
| 1201 | Leak rate rose to ~ 7.2E-9 mbar l/s. |
| | It seems the clamps on the T-valve and the hoses up to the E-box were not tight. Re-tightened them. |
| 1227 | Rate has gradually climbed to 2E-8 mbar l/s. |
| | Open turbo pump; Isolate leak checker. Turn off He gas supply. We are going to pump on the IVC again for a little while to lower the background and re-test the flanges on top of the fridge. |
| 1300 | Opened leak checker and closed the turbo pump. Leak rate rose to 4.1E-8 mbar l/s. (Note, no helium was added to the background for this check). |
| | Opened turbo pump, closed leak checker, and re-calibrated leak checker. |
| | Opened leak checker and closed turbo pump. Again, leak rate rose above 4E-8 mbar l/s. |
| | Tried to re-loosen the clamps on the T-valves. |
| 1327 | Opened the leak checker and closed the turbo pump. Leak rate still rose to 3.6E-8 mbar l/s. |
| | Opened the turbo pump and closed the leak checker. |
| 1340 | Turned on the fan pointing at the the fridge in an effort to ventilate the area and reduce the helium background. |
| 1357 | Pressure in IVC: 3.4E-4 mbar. |
| 1433 | Ran a full leak check: started at 2.3E-8 mbar l/s, ended at 2.2E-8 mbar l/s. |
| 1507 | Opened leak checker and closed turbo pump. |
| 1515 | Background leak rate stabilized at 3.16E-8 mbar l/s, IVC pressure at 6.3E-3 mbar. Began leak check |
| 1525 | The leak rate seemed to slowly increase when helium was sprayed by the metal tube fastener for the striplines. Sprayed more helium on it and the leak rate rose from 3.73E-8 mbar l/s to 5.2E-8 mbar l/s. |
| 1544 | Background leak rate now up to 6.3E-8 mbar l/s, IVC pressure is at 7.4E-4 mbar. |
| | Opened turbo pump and closed leak checker. Leak rate stabilized around 4.2E-10 mbar l/s. IVC pressure now at 5.4E-4 mbar. |
| 1645 | Opened leak checker and closed the turbo pump. Leak rate background stabilized to 5.1E-8 mbar l/s. |
| 1700 | Leak checked only the metal tube fastener for the striplines. |
| | No noticeable spike in the leak rate, it gradually got as high at 6.4E-8 mbar l/s. Perhaps we are experiencing out gassing. |
| 1752 | After using the turbo pump and fan to reduce the background rate to 3.3E-8 mbar l/s and dropping, another leak check of the upper flanges was started. |
| 1800 | Background rate has reduced to 3.00E-8 mbar l/s and is still dropping. No leaks yet detected. Began checking Ebox and surrounding flanges. During this check small fluctuations of 2.91-2.95E-8 mbar l/s were seen, but these were determined to be due to an changing background rate and not actually a leak. |
| 1850 | Leak rate started to rise after checking flange on NW40 tee closest to double-flange where striplines emerge from fridge. However, it seemed consistent with background. Leak rate reached 6.2E-8 mbar l/s very slowly. Isolate leak checker and use turbo to reduce helium leak rate. Perhaps the leak is larger, but difficult to reach. Double-flange is tilted, so would be surprised if it is vacuum-tight. |
| 1945 | Isolated turbo pump and restarted leak check. Leak rate stabilised at 5.8E-8 mbar l/s. Started checking flange on tee closest to double-flange and leak rate fell to 5.6E-8 mbar l/s. Leak rate increased when checking middle of double-flange and reached 6E-8 mbar l/s. Leak rate started to fall again when checking third indium flange from top. |
| | There is some pattern. Although we could continue to test it to make sure, it may be a better use of time to fix the tilted double-flange. Isolate leak checker and evacuate IVC with turbo pump. |