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2012/07/07

1430 Filled LN2 cold trap.
1505 Mixing chamber temperature has decreased to 85.7 mK. Unsure of reasons for this. Pressures of G1, G2 & P1 are 55 mbar, 56 mbar & 0.06 mbar respectively. Other temperature stages:
Table 1: Temperature of Stages.
Stage Measured Resistance [kΩ]
Still 4.53
Cold plate 15.0
Mixing chamber 23.9
Table 2: DIB 1, DCRC 32
Phonon Channel SQUID Bias (micro A) Lockpoint (mV) Modulation Depth (mV)
A 85.92 5.74 5.5
B 82.02 3.60 4.5
C 81.04 5.06 5.1
D 80.07 4.28 5.1
1940 Switched mixing chamber heater on (20 mW) by mistake at about 1800. Heater was switched off almost immeditately afterwards, but mixing chamber temperature rose very quickly to 500 mK. Only now has the mixing chamber temperature decreased to 88 mK. Cooling power is very poor.
None of the channels have undergone any transition, which would imply that their Tcs lie below our base temperature. DIB 1 phonon channel D lies on Side 2, the others are on Side 1. It appears as though we will require a lower base temperature. It may be worth checking DIB 3.
It would probably be more efficient to investigate our lack of cooling power.
2230 Start single-shot. Close valve 13A and open valve 9.