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2011/05/11

0100 Fill N2 cold trap full.
Start flashing detector.
1050 Filled LN2 Cold Trap.
1340 Start LHe transfer. Helium liquid level 3.0%.
1415 End LHe transfer. Helium level 94.1% .
1500 Stop flashing detector.
1750 Tower temperature a bit high at 66 mK. Pressure in P1 a bit low at 0.07 mbar - should be around 0.19 mbar at 68 mK. Increase still heater power to 3.0 mW.
1810 Tower temperature still a bit high at 63 mK. Pressure in P1 still a bit low at 0.085 mbar. Increase still heater power to 4.0 mW.
1825 Tower temperature still a bit high at 63 mK. It seems as though we have lost some of our cooling power.
Start data series regardless: 07110511_1821: -2.5 V bias DIB1; +2.5 V bias DIB2; Ba-133 source 13” below top of mu-metal shield; 40 ADC bins trigger threshold on all charge channels; charge-only.
1930 Stop data series 07110511_1821 on file 14.
Flash detector for 15 s using Berkeley's settings: LEDs 1 & 2 on both DIBs; 0.8 mA current; 50 μs on; 2.5 ms off. Tower temperature increases to 450 mK.
1940 DCRC30 started emitting a high pitch noise as soon as flashing started. Disconnecting it solved the problem.
2025 Tower temperature stuck at 80 mK, and pressures in G1 & G2 are fairly high at over 250 mbar. Decrease still heater power to 2.0 mW.
2040 Doesn't seem to be helping. Turn still heater off.
2050 Tower temperature falls very slowly, but it appears to be falling, which is an improvement.
Fill N2 cold trap full.

Looking for Neutralisation

Figure 1: First 15 minutes of data series 07110511_1821.
Figure 2: First 30 minutes of data series 07110511_1821.
Figure 3: First 60 minutes of data series 07110511_1821.