Determination and correction of the linear lattice of the APS storage ring.

Abstract

The authors have created precise linear models of the storage ring in terms of beta functions for both low-emittance and high-emittance lattices. Using these models, the beta function beating corrections have been successfully applied. The lifetime was increased by 40% for the low-emittance lattice as a result of the corrections. The models allow the user to apply predictable and precise changes to the existing lattice. For example, after applying the beta function corrections, the beta-function changes exactly coincide with the changes predicted by the model. The generated machine model contains not only the real beta functions of the ring but it also provides Beam Position Monitors (BPM) gain calibrations. This could be useful for a number of applications that rely on the BPM readings. Unfortunately, one important task has not been accomplished. The excessive number of quadrupoles per unit phase advance does not allow them to determine the real gradients for every quadrupole. Work on correcting this shortfall will continue in the future. Among other future plans is use of the response matrix fit to characterize and correct both global and local linear coupling. The implementation of a coupling calculation is rather straightforward but requires additional programming.