While this was not the first time that scientists have caused high-energy beams of electrons and pos-itrons to collide, it was the first time that the collisions occurred between beams of unequal energies. This "asymmetry" is the key to the $177-million B-Factory, which 300 physicists, technicians and workers from the Stanford Linear Accelerator Center, Lawrence Berkeley National Laboratory and Lawrence Livermore National Laboratory have labored for more than four and a half years to construct.

As its name suggests, the Asymmetric B-Factory has been specifically designed to produce large quantities of short-lived subatomic particles called B mesons. Scientists plan to compare the creation and disintegration of those particles and their antiparticles to learn more about their properties and to eventually understand why the universe is composed almost entirely of matter.

"Getting this collider to work is something like getting a mile-long line of high-performance race cars all running at the same time," says John Seeman, head of the B-Factory commissioning team that has the year-long task of working out the bugs in the new machine and getting it to run properly.

Still more work lies ahead. Experiments cannot be conducted at the B factory until a 1,000-ton particle detector known as BaBar is moved into position at the point where the two beams intersect. The detector was built by an international collaboration of more than 500 physicists and engineers in parallel with the construction of the rings. If all continues according to plan, BaBar will be installed in January.

For more information contact http://www2.slac.stanford.edu/vvc/experiments/bfactory.html