Beam lifetime at the SRS

The beam lifetime in the SRS electron storage ring at Daresbury Laboratory is governed by several processes which vary significantly according to the machine operating mode. A theoretical model of the storage ring has been developed, taking the variable vacuum chamber aperture, dynamic aperture and other effects into account to predict the expected overall beam lifetime. Measurements have been performed to separate the contributions from the different loss processes: Touschek scattering, beam-gas scattering and quantum lifetime effects. Comparison with experiment gives a reasonable agreement with theory in the different operational modes used on the SRS.