Experiments with Supersonic Beams as a Source of Cold Atoms

Figure 3.18: This shows the decay in the reflected intensity from a passivated silicon
crystal over time. The red data comes from a normal data run with the rotor spinning.
The rotor is periodically stopped to measure the reflected intensity. The red curve is
a least square fit of this decay as a double exponential. The data shown in black is
the reflected intensity from a dedicated intensity run without spinning the rotor and
where the RGA is only on to measure the reflected intensity, except for the period
noted in the figure where the RGA is left on deliberately to observe its effect.
on to measure the reflected intensity at specific intervals. The RGA is also left on for
a specific interval to observe its effect directly.
This data set, along with the measurement of the decay from a normal data
run is shown in figure 3.18. The red data comes from a normal data run with the
rotor spinning. The rotor is stopped at certain times to measure the static reflected
intensity, and these measurements are shown in red. The red curve is a least square
fit of the decay as a double exponential decay with time constants of 2.5 and 38.5
minutes. The data shown in black is the reflected intensity where the RGA is only
on measure the reflected intensity (about 1 minute) for each measurement, except for
the period noted in the figure where the RGA is left on deliberately to observe its
effect. The rotor is not spun during the taking of this data set. As seen in the figure,
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