Positron Emulator for Commisioning ILC Positron Source

The gamma-ray based positron source [1] is an attractive option for the International Linear Collider (ILC) positron option because of the less stringent target requirement and the possibility to provide polarization. The drawback is the fact that the positron accelerator system including positron linac and damping ring can not be fully commissioned until the electron accelerator system is commissioned at high energies (> 150 GeV). In this paper, we discuss a scheme that would use a low energy (∼ 100 MeV) electron beam scattered through a set of carefully selected targets to mimic phase space distribution of the positron beam. The positron “emulator” can be used to effectively commission the positron accelerator system including the capture optics, the linac, and even the damping ring before the ILC colliding electron beam is ready. Simulation results using EGS4 for beam scattering and PARMELA for beam dynamics are presented.