Lost Particles in the IR and Issues for Beam Induced Backgrounds in Higgs Factories

The loss of beam particles has to be well under control in high energy and high luminosity e⁺e^{−} colliders 'namely Higgs Factories- especially at the interaction regions. In the design stage the main beam related effects causing particle losses need to be studied in details by means of full simulation to check that machine induced background rates are tolerable for the experiments and, if not, conceive an efficient collimation system to intercept particles that would eventually be lost in the Interaction region (IR). These studies can also give a realistic evaluation of beam lifetime. We will review how main beam backgrounds have been handled at SuperB and DAΦNE and we will mention the LEP experience. A first tracking simulation of the Touschek and radiative Bhabha particles for the CEPC IR case are presented as a starting point for losses evaluation. Synchrotron Radiation, essentially determined by the beam energy, is a key issue for the IR design of Higgs Factories. A first description of the tools under development for the SR evaluation in view of the FCC-ee design study is given.