| 1620 | Commence process for cleaning Cold Trap 1. Switch over to nitrogen cold trap 2 and close valves V12A, V13A & cold trap 1 speedivalve. Open valves 11A & 8 (throttled until P1 < 1 mbar when open) to extract remaining mixture. |
| 2010 | Tower temperature 80.5 mK, P1 pressure 80 μbar, G1 & G2 around 170 mbar. It appears as though nitrogen cold trap 2 is dirtier than initially thought. Close valves 8 & 11A to see what happens. |
| 2025 | Tower temperature has decreased slightly to 80.4 mK. Pressures in G1 & G2 still as high as before. P1 pressure unchanged. Extract nitrogen cold trap 1 from its bath and pump on it with scroll pump through vent. |
| 2235 | Pressures in G1 & G2 have risen to 210 mbar & 195 mbar respectively. Rather worrying, although mixing chamber temperature has decreased to 79.5 mK. Stop pumping on nitrogen cold trap 1 after cleaning cycle, and close valves 7 & 11A. Open valve V13A to cool trap with mixture. |
| 2240 | Open valve V12A & cold trap 1 speedivalve. Close valves V12B & V13B to isolate nitrogen cold trap 2. Open valve V11B and throttle valve V8, keeping P1 pressure below 1 mbar, to bleed mixture out of nitrogen cold trap 2. |
| 2300 | Leave valve V8 open as P1 pressure drops below 1 mbar. Pressures in G1 & G2 have risen to 228 mbar & 220 mbar respectively. Temperature and exhaust pressure of 1 K pot are 1.59 K & 7 mbar respectively. It doesn't appear as though 1 K pot is being worked terribly hard, which is bad news - it would indicate a blockage in the helium cold trap. Mixing chamber temperature 79.9 mK and rising slowly. Will continue to monitor the situation. |
| 2345 | Pressures in G1 & G2 have risen to 247 mbar & 234 mbar respectively, and show no signs of stopping. It still appears as though 1 K pot is not being taxed significantly, implying that there is a blockage in the helium cold trap. Mixing chamber temperature is still high at 80.3 mK. Will need to recover mixture. Unplug DCRCs, stop 1 K pot pump and close valve V13B. Open valve V9 and monitor pressure on G2. |
| 2355 | Turn on mixing chamber heater, power 5 mW, to aid recovery. |