Beam Background Simulation and Experiment at BEPCII

A high-level beam background is a crucial challenge to future upgrades to the BEPCII collider. We report on the first separate measurement of the main beam background components at BEPCII. The separation measurement enables the beam background extrapolation towards the beam parameters assumed for the upgraded BEPCII. The measured rates of each background component are also compared with a brand-new simulation based on SAD and Geant4. The discrepancy between experiment and simulation remains 1$\sim$2 magnitudes after calibration with beam lifetime, which should be further investigated.