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Press Release: SLAC's B Factory Achieves Design Goal

Date Issued:November 09, 2000


  • P.A. Moore, Stanford Linear Accelerator Center: 1 (650)926-2605


  • John Seeman, Stanford Linear Accelerator Center: 1 (650)926-3566

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Scientists at DOEs Stanford Linear Accelerator Center (SLAC) were in the last three days of the scheduled operation of the B Factorys PEP II collider with fingers crossed. In the time remaining before the shutdown for annual maintenance, would the machine achieve the level of operation for which it was designed? The answer was a resounding yes, as the PEP II collider not only reached, but exceeded its design luminosity.

Luminosity is a measure of the rate at which interesting particle physics events occur. In this case, the events that physicists are looking for are the production of the B meson particle. The B Factory is now churning out millions of these particles per month, allowing physicists an opportunity to study the subtle differences in the behavior of matter and antimatter in the Universe. In particular, if the Universe was born with equal amounts of matter and anti-matter, why do we find ourselves living in a matter-dominated Universe? What happened to the anti-matter?

The Department of Energy is very proud of SLAC's outstanding performance on PEP-II. To reach design luminosity so soon after turn-on is a remarkable achievement, definitely one for the record books. I am looking forward to a bumper crop of physics from the B-Factory, and am keeping my fingers crossed that one or two results will create yet another November Revolution in our field, said Associate Director for High Energy and Nuclear Physics Peter Rosen. The November Revolution occurred in 1974 and signaled a new era of particle physics with the discovery of the J/Psi particle simultaneously at SLAC and MIT, and a Nobel Prize for Burton Richter (SLAC) and Sam Ting (MIT).

Since its startup in May, 1999 until now, the B Factory has exceeded the performance expectations of even its builders. This on-time on-budget facility was a $177 million collaborative project among SLAC, the Lawrence Berkeley National Lab and the Lawrence Livermore National Lab. The B factory accelerates two beams of subatomic particles to nearly the speed of light and particle collisions from the two counter-rotating beams are tracked by a detector known as BaBar.

We knew we could reach our design goals, but it was a matter of when. We had planned to end this run in July but the machine was doing so well that we extended the run, knowing that our goal was close, said SLAC Director Jonathan Dorfan. Prior to becoming Director of SLAC in September 1999, Dorfan had been the project leader for the B Factory.

In the operation of the collider from May 1999 through October 2000, PEP-II made steady progress. And on Sunday October 29 at 6 am the luminosity exceeded 3x1033 per square centimeters per second for the first time. Later that day the luminosity reached 3.1 x 1033, thus exceeding the design goal for instantaneous performance. Sustained performance is just as critical a goal. Starting in July 2000, PEP II exceeded the design per month B meson production culminating in its best operations during the month of October, delivering 10 percent more B mesons than a design month along with other interesting events for ancillary areas of physics that deal with charm and tau particles. Since May 1999 PEP II and BaBar have recorded more than 23 million B mesons, giving physicists a rich supply for study.

During the three-month shutdown of the B factory now in progress, several large installation tasks will be performed. PEP-II and BaBar will turn on again on February 1, 2001 and run until August 31, 2001. With our first year of operations having gone so well, we are anticipating with excitement the first published results, said Dorfan.

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