Robustness of Resonance Free Lattices Against Gradient Errors

Resonance-free lattices make it possible to cancel the effect of non-linear resonances due to systematic multipoles in an alternating gradient circular machine. These lattices are made of identical cells with specified phase advances. It is therefore mandatory to examine to what extent the property remains valid in presence of gradient errors. In the case of LHC, three times the nominal gradient errors are acceptable from the point of view of both a3 and b4 components.