| 0320 | IVC pressure is 0.01 mbar. This is close to the limit of the scroll pump so it's unlikely to fall further. The size of the gap between the flanges is large enough for me to see from where I'm sitting. Although we would go beyond the recommended torque settings, we should probably attempt to tighten the screws further. Get kitted up: I'm going in! |
| 0400 | There is still a gap, but it is smaller than it was. I'm worried about shearing a screw, and there is very little give left. I suspect that there should be a hap due to the thicker indium wire we are using. We can perform a leak check in the morning to see if it's leaky at room temperature. |
| | IVC pressure is 0.01 mbar. Evacuate IVC with turbo pump. Isolate and turn off scroll pump. |
| 1000 | Warmed up leak checker and re-calibrated. Background leak rate: 6.2E-9 mbar l/s. |
| 1032 | With spray needle, did helium spray test to leak check lines and flanges leading to IVC on top of the fridge. No leak detected. |
| | Leak checked top two indium seals. No leak detected. |
| | Leak checked the large top flange. Leak rate gradually rose to 7.8E-9 mbar l/s over a time span of 5-10 min, but no gross leak detected. Waiting to see where it stops increasing. |
| 1054 | Leak rate is at 1.1E-8 mbar l/s (though still slowly increasing, it seems). I'm going to go ahead and test the bottom flange to see if there is a gross leak. |
| 1058 | Leak rate after testing bottom flange: 1.3E-8 mbar l/s. No gross leak detector for the bottom flange. |
| | I will start evacuating the IVC again for a little while and spray test the upper large flange again with a higher He gas flow. I will check the rate to see if it increases quickly (or what it increases to in 5-10 minutes. Will re-evacuate again and then I'll do the same with the bottom flange. |
| 1131 | Checked the leak rate and it's around 1.6E-8 mbar l/s. Keep evacuating. |
| 1317 | Tightened screws on bottom flange once around. Background leak rate: 9.6E-9 mbar l/s |
| 1322 | Sprayed the large top flange again. Waiting to see how leak rate changes. |
| 1327 | Interesting. The leak rate hasn't increased. In fact, it's been decreasing (which makes sense since it's pumping out the IVC). 9.2E-9 mbar l/s. Going to recheck the other top flanges before moving back down to the bottom seal. |
| 1433 | Second round of leak checks turned out okay. No gross leak still. Background leak rate was 8.5E-9 mbar l/s. Isolated IVC in order to prepare pumping on dewar jacket. |
| 1500 | Electrical recheck shows no change from previous check. |
| 1540 | Start pumping out dewar's vacuum jacket. Pressure rose to 0.046 mbar before falling again. |
| 1921 | Finished cleaning helium and nitrogen cold traps. |
| 2135 | Stop pumping dewar's vacuum jacket. Pressure <4E-3 mbar. |
| 2225 | Fill N2 cold trap full. |
| 2330 | Start cryocleaning mixture through nitrogen cold trap 2. Valve V6 on IGH open to 12.0%. |
| 2345 | Dewar raised, evacuate main bath. Pumping rate seems to be faster than usual, which is puzzling. However, after double checking the connections, it appears as though we are pumping on the main bath. Everything is probably fine. |
| | Cryocleaning has stagnated. Open valve V6 on IGH to 12.5%. |
| 2355 | Evacuate 1 K pot. |
| | Background helium leak rate 3.1E-9 mbar l/s. Overpressurise main bath with helium gas. Helium leak rate rises to 3.7E-9 mbar l/s. Rate of increase is gradual, and may be background. Anyway, no sign of a gross leak. |
| | Cryocleaning has stagnated. Open valve V6 on IGH to 13.0%. |