HOM heating at the PEP-II B-Factory IR beryllium vacuum pipe

The higher-order-mode (HOM) heating of the central beryllium beam pipe in the PEP-II B-Factory interaction region is evaluated. Both single and multi-bunch effects are considered. While single-bunch heating is not an issue, resonant heating due to multiple bunch passages is found to be unacceptable. Modifying the IR configuration around the central pipe has been shown to alleviate this problem. Simulation results indicate that the new design is sufficiently effective in reducing possible resonant heating down to a level that is within existing cooling requirements