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<b>High Energy-Astrophysics</b><br><i>Charm in China: BEPCII/BESIII</i>

Tuesday, September 8, 2009
12:00 AM
335 West Hall

Speaker: Fred Harris (University of Hawaii)

The Beijing Electron-Positron Collider has been upgraded to a two-ring collider (BEPCII) with a design luminosity of $1 \times 10^{33}$cm$^{-2}$ s$^{-1}$ at a center-of-mass energy of 3.78 GeV. With this luminosity, the brand new BESIII detector will be able to collect, for example, more than 1 billion $J/\psi$ events in one year of running. It will operate between 2 and 4.6 GeV, allowing precision studies of charmonium (J/psi, psi(2S), psi(3770), eta_c, chi_cJ, and h_c) and charm (D and D_s mesons) and improved determinations of the tau mass and the hadronic cross section (R) in this energy region. This will be a unique facility in the world opening many physics opportunities. The first event was obtained in July 2008. BEPCII has already reached 30\% of design luminosity, and BESIII acquired a sample of 100 M psi(2S) events, or four times the CLEOc sample, in four weeks of running this spring and about 200 M J/psi events, or about four times the BESII J/psi sample in six weeks of running this summer. The design, performance, and status of the detector and future physics goals will be discussed.