| 0045 | Mixing chamber temperature rose to 60.8 mK. It's been rising for the last couple of hours, and the rate seems to be increasing. Helium liquid level is 6.7%, which although low, is still enough. Additionally, 1 K pot doesn't appear to be empty. |
| | Filling the N2 cold trap seems to have brought the temperature back down to 59.6 mK and still falling. Pressures in G1 & G2 are 57 mbar & 65 mbar respectively, indicating a possible blockage. Certainly the fact that filling the cold trap had an effect on the temperature seems to indicate that nitrogen cold trap needs to be cleaned again. It may be worth waiting until the morning before deciding if we need to take any action. |
| 0050 | Helium liquid level is now 7.6%. It's not surprising it appears to have risen, as the meter is inaccurate below 10%, and has oscillated like this in the past. However, this would translate to 4 hours of helium left in the main bath before the 1 K pot starts to warm up. Therefore, it would be prudent to perform a helium transfer now rather than in the morning. |
| 0145 | Start helium transfer. Helium liquid level 5.8%. |
| 0245 | Stop helium transfer. Helium liquid level 78.0%. |
| 0305 | Mixing chamber temperature has been rather erratic over the last couple of hours. It reached a little above 58 mK before rising again to almost 60 mK, and then falling to its current temperature of 59.4 mK. It may have stabilised, and we may have a better idea of this in the morning. Pressures in G1 & G2 are 57 mbar & 69 mbar respectively. |
| 0510 | Fill N2 cold trap full. |
| | Mixing chamber temperature still a little erratic, but seems to be stabilising. Pressures in G1 & G2 are 56 mbar & 69 mbar respectively. |
| 1835 | Fill N2 cold trap almost full; perhaps a litre shy. |
| | Pressures in G1 & G2 are 56 mbar and 78 mbar respectively. Decision was taken earlier today not to clean cold traps in favour of additional data acquisition with Ba-133 source. Mixing chamber temperature appears to be fairly stable at 59.0 mK, although there were minor fluctuations overnight. May clean cold traps tomorrow or on Thursday depending on how the situation develops. |