Figure 4. Fractional-frequency spin-exchange shift (for constant frequency stability) as a function of Ramsey time for several different launch parameters. The number of balls per lineside is a measure of how many balls pass through the system before moving to the other side of the central fringe so as to locate and servo-control the system to the center of the resonance.For each curve the fractional frequency shift for the spin-exchange effect decreases with increasing Ramsey time, and then flattens out in the region between Ramsey times of 10 and 100 seconds. This shift also decreases dramatically in going from 1 ball per lineside to 10 balls per lineside, but exhibits much smaller improvement as the number of balls per lineside is further increased to 20.
Online: April 2000