Experiments with Supersonic Beams as a Source of Cold Atoms
Experiments with Supersonic Beams as a Source of Cold Atoms
Experiments with Supersonic Beams as a Source of Cold Atoms
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Figure 3.17: The calculated velocity <strong>of</strong> the reflected beam plotted against the velocity<br />
<strong>of</strong> the crystal. The red line is the le<strong>as</strong>t square fit <strong>of</strong> the data, while the black line<br />
shows the expected velocity dependence from simulation.<br />
velocity is calculated from the arrival time <strong>of</strong> the beam and from the beam path length<br />
calculated from the nozzle to the rotor and from the rotor to the detector. This path<br />
length depends on the ph<strong>as</strong>e <strong>of</strong> the rotor, and is calculated from the nozzle delay<br />
time used to optimize the reflected beam signal. The beam velocities are calculated<br />
by performing a Gaussian fit <strong>of</strong> the data for each individual nozzle pulse. The mean<br />
<strong>of</strong> the center <strong>of</strong> the Gaussian fits is taken <strong>as</strong> the arrival time, while the standard<br />
deviation <strong>of</strong> the centers is used to calculate the error.<br />
The red line shown in figure 3.17 is the le<strong>as</strong>t square fit <strong>of</strong> the data, while the<br />
black line is the velocity dependence predicted by simulation. While the dependence<br />
expected from simulation lies <strong>with</strong>in the error bars for the me<strong>as</strong>urement, there seems<br />
to be a real difference in the slope <strong>of</strong> the two lines. This is most likely a result <strong>of</strong> the<br />
manner in which the optimal nozzle delay is found. Since the distance between the<br />
reflection point and the detector is short compared <strong>with</strong> the total travel distance, the<br />
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