| | Status: Can't cool below around 3.5 K, suspect a touch somewhere to the 4K stage. Warming up. He gas in IVC and cryostat vacuum jacket. MC and Still heaters on overnight @ 20 mW each. |
| 0720 | MC(Cernox) = 260.2 K |
| 0750 | MC(Cernox) = 262.6 K |
| | this is a fast warming trend, time constant around 7.5 hours. Should hit 273 K at 10:30. Why so fast this time? Is it because I used Helium instead of Nitrogen? Or is it because of the touch from (probably) the 100mK stage to the 4mK stage? |
| 1045 | MC(Cernox) = 273.8 K (on LabVIEW vi. 272.5 K on LakeShore bridge display.) Warm enough to drop the bath. |
| 1045 | Cryostat vacuum jacket = 2.5 mbar. Start pumping it out with scroll pump. |
| 1050 | Start pumping cryostat vacuum jacket with turbo pump. |
| 1150 | Turbo = 25 nbar, cryostat vacuum jacket = 630 nbar with pump valved out |
| 1252 | Turbo = 16 nbar, cryostat vacuum jacket = 300 nbar with pump valved out |
| 1303 | Stop pumping cryostat vacuum jacket with turbo pump. |
| 1315 | Lower main bath. IVC is pretty cool to the touch but doesn't frost up. Realized I still have the MC heater on so MC temp may be higher than IVC temp |
| 1325 | Turn off MC heater and Still heater. MC temperature doesn't change much. |
| 1330 | IVC = 4.6 mbar. Fill to 1 bar with N2. |
| 1450 | We have opened the IVC and removed the 4K stage. There is no evidence of a touch from a <4K stage to the 4K stage. The stripline buckle is well separated from the 100mK can. There's no indication that the central bottom disk of the tower (600mK stage) is touching anything on the 4K stage (except of course through the SQUET flyover cables). The plates covering the tower wiring on the faces at the two bottom stages seem properly separated and don't seem to have shifted. We thought about how the striplines need to go up the side of the IVC without touching the 100mK can, and if they got loose at the top somehow there could be a touch; the striplines seem quite snug though where they go through the buckle, nothing seems loose. At the 100mK stage there is no indication that the heatsink connections are oriented wrong, they seem well separated from the IVC walls and from the tower faces. The 100mK shields seem basically oriented well too, with proper gaps between them and the tower. |
| 1550 | Reinstalled the inner 100mK shield pieces, being careful about the gaps. Reinstall 4K stage and SQUETS. |
| 1555 | DIB4 electrical check: looks OK |
| 1600 | DIB1 electrical check: looks OK |
| 1605 | DIB3 electrical check: looks OK. (same opens as before, SQUID A open, SQUID B reads high, 100s of kOhm) |
| 1630 | IVC is closed. Start pumping with scroll while continuing to tighten screws |
| 1655 | Start pumping IVC with turbo pump |
| 1740 | Turbo on IVC = 220 nbar |