  We present a design of a spin-flip Zeeman slower controlled by a fast
feedback circuit for a sodium Bose-Einstein condensate apparatus. We also
demonstrate how the efficiency of the slower strongly depends on its intrinsic
parameters, and compare these observations with a few theoretical models. Our
findings lead to a simple three-step procedure of designing an optimal Zeeman
slower for neutral atoms, especially for those atomic species with high initial
velocities, such as sodium and lithium atoms.
