Stanford Linear Accelerator Laboratory's Asymmetric B-Factory

All particles of matter have mirror images called antimatter. The universe prefers matter—antimatter is created only in laboratories today—and physicists are not sure why. The answer may lie in differences in the ways unstable particles of matter and antimatter decay, or break down into more stable particles. Physicists now have the accelerators needed to test these differences, thanks to Piermaria Oddone of Lawrence Berkeley National Laboratory, the father of the "B-factory" (so-named because it makes particles containing "bottom" or b quarks). In the late 1980s, Oddone suggested looking for the matter/antimatter asymmetry with a collider of electrons and positrons (anti-electrons) using beams of unequal energy, a radical approach at the time. His proposal led to Stanford Linear Accelerator Laboratory's Asymmetric B-Factory, a collaboration of three national laboratories that began operating in 1999. Researchers use it to measure the decay of B mesons, rare particles that are a mix of matter and antimatter. The asymmetric design allows particles to move in a way that is conducive to study and provides for high luminosity (rate of particle collisions). In 2000, the first results were reported of a breakdown in matter/antimatter symmetry in B mesons.

Scientific Impact: The collider design was unprecedented and has achieved luminosities that exceed the previous world record. Operation of the Asymmetric B-Factory promises to provide a stringent test of the Standard Model, physicists' current theory of matter and the forces of nature.

Social Impact: These studies will help humans better understand the origins of the universe and why matter, including the Earth and its inhabitants, exists. (A preference for antimatter in the universe would have annihilated all matter.) In addition, the collider design project produced an electronics technology spin-off, a new methodology for circuit board design and fabrication.

Reference: P. Oddone, Proceedings of the UCLA Workshop on Linear Collider B B-Factory Conceptual Design, ed. by D. Stork (1987).

URL: http://www2.slac.stanford.edu/vvc/experiments/bfactory.html
http://www.lbl.gov/Science-Articles/Research-Review/Highlights/2000/stories/physics/yearone2.html

Technical Contact: Pier Oddone, pjoddone@lbl.gov
Jonathan Dorfan, jonathan@slac.stanford.edu

Press Contact: Jeff Sherwood, DOE Office of Public Affairs, 202-586-5806

SC-Funding Office: Office of High Energy and Nuclear Physics