| 0300 | Conduct electrical check. Found QET C Return 1 & Feedback Coil D on stripline 19 shorted to ground on ebox side. Removed D-sub 50 connector from inner ebox plate, but could not find the fault. Neither did the fault return when placed back in socket. We've had similar problems with this stripline in the past, which have magically disappeared when the connector was removed and reattached. Best to keep an eye on it. Other striplines passed continuity checks with no problems. |
| 0500 | IVC sealed. Evacuate IVC overnight. |
| 1415 | Leak check at room temperature. Background helium leak rate 7.2E-9 mbar l/s. Appears that there is indeed a leak, but fortunately it's on the stainless steel tee at the top of the fridge through which the stripline runs through: helium leak rate jumped to 6E-7 mbar l/s. Other ends of tee show some signs of a leak, but this may be due to helium leaking through leaky flange. |
| | Continue leak check. New background helium leak rate 8.6E-9 mbar l/s. |
| 1655 | No other leaks found. Helium background leak rate did reach 3.6E-8 mbar l/s, but this was a gradual climb rather than a peak. Apart from the tee, we look good. |
| | Took clamps off each end of stainless steel tee to adjust gaskets. Start evacuating IVC again. |
| 1725 | Isolate turbo pump and try again. Background helium leak rate 1.9E-8 mbar l/s. Leak rate remained unchanged when conducting spray test around stainless steel tee's flanges: good news; looks like we solved it! |
| | Fill N2 cold trap full. Open manual valves on dump. Stop pumping on mixing chamber lines with 1 K pot pump, and start pumping on them with He-3 pump. |
| 1900 | Simple electrical check to make sure nothing was shorted to ground. Results were positive. |
| 2029 | The north pulley was moved south by ~16mm to center the dewar with the fridge. |
| 2305 | Raise dewar, evacuate main bath and fill with He-4 gas. Background helium leak level 7.5E-9 mbar l/s. Helium leak level rose to 8.3E-9 mbar l/s: no gross leak. |
| | Evacuate 1 K pot. |
| 2315 | Fill IVC with 5.4 mbar N2 exchange gas. |
| 2325 | Start nitrogen transfer. |
| 2340 | Start cryocleaning mixture through nitrogen cold trap 2. |