OPTIMIZATION OF THE e − e − OPTION FOR THE ILC

The e − e − running mode is one of the interesting physics options at the International Linear Collider (ILC). The lu- minosity for e − e − collisions is reduced by the beam-beam effects. The resulting beamstrahlung energy loss and beam- beam deflection angles as function of the vertical transverse offset are different compared to the e + e − collisions. In this paper, the dependence of these observables with the offset for different beam sizes has been analyzed to optimize per- formances for the e − e − mode, taking into account the re- quirements of the beam-beam deflection based intra-train feedback system. A first study of the implications for the final focus and extraction line optics is also presented for the cases of the 20 mrad and 2 mrad ILC base line crossing angle geometries.