Abstract:
The lifetime of a light source with small emittance like the
Advanced Light Source (ALS) is usually limited by the
momentum acceptance of the ring. Large momentum acceptances
are reached by providing enough RF voltage and by avoiding a
degradation of the dynamic momen-tum aperture. At the ALS
the size of the momentum ac-ceptance depends strongly on the
transverse dynamics. It is very sensitive to machine
conditions such as the tunes and chromaticities since
depending on those conditions the Touschek scattered
particles explore different resonance re-gions in the phase
space. In this paper we show that by using a single-turn
pinger magnet together with turn-by-turn beam position
monitors (BPM) one can identify the cause of a reduction in
momentum acceptance and take steps to improve the
acceptance.