PEP II: SLAC‐based asymmetric B factory

The proposal for upgrading the existing PEP collider at SLAC to enable the copious production of boosted B mesons is the result of several years of collaborative study by groups representing LBL, LLNL, and SLAC. The PEP II design has evolved in a considered fashion from its initial conceptualization to a very advanced level of understanding, well‐substantiated by R&D results on the key design issues. We describe the proposed upgrade, review the early conceptual decisions, outline the significant remaining questions, and briefly describe current results from the ongoing R&D effort which have shown these questions to be tractable and the initial concepts to be sound.