The Interaction Region of PEP-II

The PEP-II e+e- collider turned off last year after a very successful 9 years of running. The accelerator achieved a peak luminosity of 12 x 1033 cm-2 s-1, 4 times over the design of 3 x 1033 cm-2 s-1. The peak beam currents were quite high; over 3 A for the positron beam and over 2 A for the electron beam. The beams were stored in separate storage rings. The PEP-II design called for a head-on collision at the interaction point (IP). This was possible because of the asymmetric beam energies (9 on 3.1 GeV) and was achieved using permanent magnet (PM) dipoles. I describe the actual interaction region (IR) layout including some of the design constraints that led to the final design and discuss operation issues related to the IR design.