CESR luminosity upgrades and experiments

The Cornell Electron Storage Ring (CESR) has provided over 2.5 fb ^-1 integrated luminosity on the Y(4S) resonance and nearby continuum, facilitating measurements of B meson decays. In order to seek out rarer events, the luminosity of the storage ring must maintain a geometric growth. The luminosity upgrade program of CESR provides this growth capability while utilizing many of the developments in technology and accelerator physics required for later upgrade to an asymmetric B factory. All upgrades incorporate approximately the same per-bunch parameters as in CESR´s present operation. The next step in the upgrade replaces the individual bunches with “bunch trains,” or closely spaced groups of bunches treated as a single bunch by the pretzel separation secheme. The higher beam currents will require improvements to the RF, vacuum, feedback, and injector systems. Separation at the parasitic interaction points near the main interaction point is provided by a small horizontal crossing angle. Machine experiments have been conducted to determine criteria for separation at parasitic crossings and measure the effects of small crossing angles on beam-beam dynamics, as well as study other topics related to the upgrade program