Beam optics studies for the CEBAF Accelerator

Measurements of differential orbits excited by two pairs of horizontal and vertical connectors, and by a change of the energy gain for the first one of two superconducting linacs allowed one to perform on-line control of the machine optics which provided valuable information for studying optics discrepancies. Off-line analysis of the data has uncovered a number of malfunctioning hardware pieces, e.g., improperly functioning BPMs and incorrectly focusing quadrupoles. It also indicated that the dipoles have significant focusing terms, which have to be taken into account to build a predictable optics. The analysis resulted in a significantly improved optics model for the CEBAF recirculator. The new optics preserved desired lattice architecture and orthogonal tunability. The presented approach was proven very successful in minimizing required tuning time and in building a more accurate theoretical model of beam transport for the CEBAF accelerator