Abstract:
The momentum aperture of a storage ring is a
very important parameter that strongly
influences the performance, especially the
beam lifetime. For the special case of
synchrotron light sources with small
emittance like the Advanced Light Source
(ALS), the momentum aperture depends strongly
on the transverse dynamics. It is very
sensitive to machine conditions such as the
tunes, chromaticities, lattice symmetry, and
spurious coupling, since depending on those
conditions the Touschek scattered particles
explore different resonance regions in the
phase space. In light sources, the momentum
aperture usually also depends strongly on the
vertical physical aperture. Applying
frequency analysis techniques in simulations
and for turn-by-turn orbit measurement data
provides a very powerful tool to measure and
understand limitations of the dynamic
momentum aperture. The techniques presented
are applicable to other light sources, as
well as damping rings and many types of
colliders.