Major conclusions.

We see no evidence for the previously observed stochastic behaviour which was witnessed even while the instrument was kept stationary. The indication is that the electronic upgrades have dramatically improved the TTF performance to the extent that we can now monitor its response to external effects. The TTF has a slow drift with ambient temperature, and appears to experience flexure as a function of slew angle. But it is important to note that the TTF response is well behaved with respect to both effects. Furthermore, the total amplitude of all drift effects is well within the spectral bandpass over the course of the tests. Thus, regular calibrations can be used to correct the TTF zeropoint.

 

Figure 2: TTF drift vs. temperature for Sequences B and C in Fig. 1.