|Effect of the undulator in IR4 on the LHC beam|
|F. Méot, A. Verdier|
An undulator is installed in IR4 to produce synchrotron radiation. The perturbation it introduces in LHC is examined. It has little effect on the closed orbit, a negligible effect on the tune. Its intrinsic non-linearities are negligible (analysis by ray tracing). Specifications on the multipole content of its integrated field are given to produce no effect on the dynamic aperture.