2021/04/05 (Monday)
- Lab in-person: Matt
- Virtual partner: Zach
| Status | Run 74 in progress. Warmed the fridge to fix short and thermal touch. Helium gas in cryostat vacuum jacket, partially pumped out. Mixture cryocleaned four times. IVC sealed and pumping for several days. |
|---|---|
| We've been seeing a high leak signal in the IVC, slowly falling as we continue to pump. | |
| 1025 | Matt enters lab |
| 1030 | Turbo on IVC = 16 nbar. With Turbo valved out for 1 minute, IVC = 250 nbar. |
| 1055 | Pump on IVC with LD, close Turbo valve and wait 1 minute: 162 pbarL/s. |
| It's continuing to improve, slowly. It seems to be falling exponentially. At the current trend, tomorrow it should fall below 100 pbarL/s, and it won't reach 10 pbarL/s until the 10th, 5 days from now. | |
| 1105 | Start cryocleaning mixture through LN2 Cold Trap 1, V6 = 12.4% |
| 1125 | Increase V6 → 12.6% to restart flow |
| 1145 | Increase V6 → 12.7% to speed up flow |
| 1205 | Stop cleaning through Trap 1 after 60 min. G2 flow pressure was 585-700 mbar. Pump mixture to dump. Removed 4.3 mbar. |
| 1125 | Leak signal settles around 189 pbarL/s. Squirt around IVC joint - no increase. Squirt around stripline elbow: signal rises to ~500 pbarL/s. Ok so that leak is still present. |
| 1135 | Open Turbo Pump valve a little, enough so that the leak signal falls below 100 pbarL/s, so that maybe it will be more sensitive. Around 93.0 pbarL/s, fluctuating by a few 10ths. Squirt around IVC joint: leak < 0.5 pbarL/s. There may have been an increase of a few 10ths but that also may have been helium floating up to the stripline elbow. I think the IVC seal is OK. |
| 1150 | Remove clean tent from bottom of fridge. Reattach fill tube with funnel to IVC exterior. |
| 1200 | Removed covers from pit. Used the long 2×4 to put through the handles to prevent covers from falling in. Wore gloves to avoid splinters. |
| 1235 | Start cryocleaning mixture through LN2 Cold Trap 2, V6 = 12.8% |
| 1245 | Increase V6 → 12.9% to speed up flow |
| 1315 | Increase V6 → 13.0% to speed up flow |
| 1345 | Stop cleaning through Trap 2 after 70 min. G2 flow pressure was 585-700 mbar. Pump mixture to dump. Removed 3.7 mbar. |
| 1250 | Finish raising Main Bath and replace pit covers, again using the long 2×4 |
| 1435 | Finish tightening all Main Bath bolts. Note that several of the small bolts required 2 washers. Probably makes sense to use 2 washers on all of them next time. |
| 1435 | Pump on IVC with LD, close Turbo valve and wait 1 minute: 155 pbarL/s. |
| 1440 | Check contents of warm LN2 Trap 1: 4.3 mbar. Pump out with Scroll Pump |
| 1500 | Apply duct tape around stripline elbow in hopes of blocking some of the helium that might leak in during transfers |
| 1530 | Matt exits lab |