Operation of CESR as a low emittance X-ray source

The Cornell Electron Storage Ring (CESR) was operated with a horizontal emittance of 65 nm-rad to produce hard X-rays from an undulator. Because all of the storage ring quadrupoles are individually powered and under software control, hardware modifications were not needed to reduce the emittance from its usual value of 166 nm-rad during colliding beam operation. Up to 35 mA could be stored in a single bunch, and a total of 115 mA was stored in six bunches. A vertical emittance of less than 1 nm-rad was observed at low currents. The undulator did not significantly affect the behavior of the beam in the storage ring.<>