BaBar experiment

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In the field of particle physics BaBar is an international collaboration of more than 550 physicists and engineers investigating CP-violation effects using the BaBar particle detector at the Stanford Linear Accelerator, Stanford, CA, USA. If the CP symmetry holds, the decay rate of B meson particles and their anti-particles should be equal. Analysis of the BaBar results showed this was not the case—in the summer of 2002, definitive results were published based on the analysis of 87 million B/B-bar meson-pair events, clearly showing the decay rates were not equal. Consistent results were also gathered in the Belle experiment at the KEK laboratory in Japan.

CP-violation was already predicted by the Standard Model of physics but the BaBar detector has increased the accuracy to which this effect has been experimentally measured. Currently results are in agreement with the standard model, but further investigation of a greater variety of decay modes may reveal discrepancies in the future.

The BaBar detector is a multi-layer particle detector. Its large solid angle coverage, vertex location with precision on the order of tens of micrometres (provided by a silicon vertex detector), good pion-kaon separation at multi-GeV momenta (provided by a novel Cherenkov detector), and few-percent precision electromagnetic calorimetry (CsI(Tl) scintillating crystals) allow a list of other scientific searches apart from CP violation in the B system. Studies of rare decays and searches for exotic particles and precision measurements of bottom and charm mesons and tau leptons are possible.

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Notable Events

On 9 October 2005, BaBar recorded a record luminosity just over 1x10³⁴particles/cm²/s delivered by the PEP-II positron-electron collider.Template:Ref This represents 330% of the luminosity that PEP-II was designed to deliver, and was produced along with a world record for stored charge in an electron storage ring at 1732 mA, paired with a record 2940 mA of positrons. "For the BaBar experiment, higher luminosity means generating more collisions per second, which translates into more accurate results and the ability to find physics effects they otherwise couldn’t see."Template:Ref

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