The PEP-II B-factory at the Stanford Linear Accelerator Center (SLAC) completed its first experimental run at the end of October after achieving record collision rates and producing more than 23 million pairs of B mesons. Funded by $177 million from the US Department of Energy, this innovative electron-positron collider has exceeded most of its challenging design goals.
PEP-II was originally designed to attain a peak luminosity of 3.0 x 1033/cm2/s. Its designers expected the collider to take about two years to reach such a high luminosity, well beyond that of any other machine before, especially given the added complexity of its unequal beam energies. However, the team of physicists commissioning the machine, led by John Seeman of SLAC, passed this mark on Sunday 29 October – hardly 17 months after the first collisions had been recorded in May 1999. PEP-II now holds the world’s record for peak luminosity, at 3.1 x 1033/cm2/s.
In machine physics runs during the last three days of October, PEP-II also hit a new record for positron current, reaching the design value of 2.14 A in 1660 circulating bunches. Things look good for the upcoming 2001 run, which will begin in February and have a luminosity goal of 5 x 1033/cm2/s.
