2012/04/15
| 1550 | Performed spray test. Background helium leak level 1.6E-9 mbar l/s. Helium leak rate gradually increased to 2.0E-9 mbar l/s: no leak. |
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| Fill N2 cold trap full. Close gate valve and condenser line speedivalve to isolate fridge. Pump out nitrogen cold trap 2. Pressure in dump 737 mbar: there is a lot of contamination. Will cryoclean mixture tonight, clean cold traps tomorrow morning, and cryoclean mixture again for at least an hour before blowing out nitrogen. | |
| 2000 | Raise dewar. Evacuate and flush main bath. |
| Commence nitrogen transfer. | |
| 2115 | Nitrogen level meter resistance 1.34 kΩ. Conclude nitrogen transfer. |
| 2225 | Fill N2 cold trap full. |
| 2242 | Close V6 down to 13.4%. Cold trap was icing up. G2 = 540; G1 = 463 mbar |
| 2333 | Close V6 down to 12%. |
Plastic Spacers between IVC & G10 Plate
G10 plate found to be off-centre when dewar was lowered at the end of Run 26 (problem was also noticed at the end of Run 25, although it was incorrectly thought that the plate was tilted rather than off-centre at this stage). The plate was found to obstruct vertical movement of the dewar. As a temporary solution, cylindrical plastic spacers have been manufactured to sit between the G10 plate and IVC as shown in Fig. 1. The G10 plate has also been straightened. Both nitrogen and helium transfer tubes mate easily with cone.
| Figure 1 : Plastic spacers between IVC & G10 Plate |
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