Developments in the ray-tracing code Zgoubi for 6-D multiturn tracking in FFAG rings

A geometrical method for 3-D modeling of the magnetic field in scaling and non-scaling FFAG magnets has been installed in the ray-tracing code Zgoubi. The method in particular allows a good simulation of transverse non-linearities, of field fall-offs and possible merging fields in configurations of neighboring magnets, while using realistic models of magnetic fields. That yields an efficient tool for FFAG lattice design and optimizations, and for 6-D tracking studies. It is applied for illustration to the simulation of an acceleration cycle in a 150 MeV radial sector proton FFAG.