Note 11/29/2005: This is a legacy page that is being left up as a source of background information and useful links, and has been receiving only the lightest of maintenance. PEP-II has been in commission and providing data for some years now. Its key technical people at LBNL are affiliated with or contactable through the Center for Beam Physics.

High-Luminosity Collider R&D

Contact: Program Head Michael Zisman .

The worldwide high-energy physics community has active research programs in two main areas-the energy frontier and the intensity (or luminosity) frontier. The former experimental thrust is represented by the experiments being carried out at the Fermilab Tevatron and the Large Electron-Positron (LEP) Collider, and those planned for the Large Hadron Collider (LHC). The latter program is embodied in the research to be carried out at the so-called particle factories, of which both B and phi factories (PEP-II and KEKB, and Daphne, respectively) are now under construction.

They are called "factories" to connote the copious quantities of particles they are designed to produce and the factory-like reliability that is necessary to ensure sufficient data. (A B meson is a particular type of short- lived subatomic particle. Of particular interest is its production together with its antiparticle, a B-bar.) B factories enable fundamental studies of charge-conjugation and parity (CP) violation and other phenomena measurable through rare B-meson decays. Our group's interest has naturally focused on the PEP-II Asymmetric B Factory because of the new facility's proximity to us. PEP-II was built by a collaboration of Berkeley Lab, the Stanford Linear Accelerator Center (SLAC), and Lawrence Livermore National Laboratory (LLNL). Its reason for existence-the study of B-meson decays-will be one of the key elements of worldwide high-energy physics investigations for many years to come.

Such studies are presently limited by the relatively low rate of events produced at electron-positron colliders such as the Cornell Electron Storage Ring (CESR). To study the most interesting processes within the Standard Model-rare decays and especially the phenomenon of charge-conjugation-parity (CP) violation-an effective increase in the event rate of at least a factor of 100 is required.

Both PEP-II and KEKB achieve these higher event rates by increasing the luminosity by a factor of 10 compared with present-day machines and by simultaneously enhancing the event sensitivity through the use of energy-asymmetric collisions (equivalent to another factor of 10 in luminosity). With a peak luminosity of 3 ¥ 1033 cm-2s-1, PEP-II will conduct a research program to determine the origins charge-conjugation and parity (CP) violation and other phenomena measurable through rare B-meson decays. An equivalent effort will be mounted at KEKB.

The ultimate goals are a better understanding of the Standard Model of Particles and Interactions-the prevailing theoretical framework of the physics of particles and fields- and possibly an explanation of why the universe is dominated by matter rather than antimatter.

Work on PEP-II began in January 1994, and the Department of Energy authorized it as a construction project ("Key Decision 3") that September. The dedication ceremony was held October 26, 1998. We had primary responsibility for the design, construction, and commissioning of the new low-energy ring, which is one of the most challenging storage rings ever designed. Accelerator physics, magnets and supports, vacuum systems, and electrical and electronic systems (such as power supplies and feedback systems) were our principal contributions to the PEP-II collaborative effort.

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