Beam blowup due to synchro-beta resonance with/without beam-beam effects

Abstract

A blowup of vertical emittance has been observed in particle tracking simulations with beam-beam and lattice misalignments. It was somewhat unexpected, since estimation without lattice errors did not predict such a blowup unless a residual vertical dispersion at the interaction point (IP) is larger than a certain amount. Later such a blowup has been seen in a tracking of lattices without beam-beam effect. A possible explanation of the blowup is given by a Vlasov model for an equilibrium of quadratic transverse moments in the synchrotron phase space. This model predicts such a blowup as a synchro-beta resonance mainly near the first synchrotron sideband of the main x-y coupling resonance line.Comment: Presented at the 62nd ICFA Advanced Beam Dynamics Workshop on High Luminosity Circular e+e- Colliders\\(eeFACT 2018), Hong Kong, Sep. 2018, WEXBA0