Operating Experience with Superconducting Rf at Cesr and Overview of Other Srf Related Activities at Cornell University

In the two years past since 8 RFSC Workshop the major efforts of the SRF group at Cornell University were concentrated on the completion and commissioning of the superconducting RF system for the Cornell Electron Storage Ring (CESR) e+e− collider [1, 2]. Four singlecell niobium higher-order mode (HOM) damped cavities replaced four 5-cell normal conducting RF cavities. The RF system upgrade began in 1997 and proceeded replacing cavity by cavity until installation of final SRF cavity in September 1999. Superconducting cavities helped CESR to reach total beam current of 550 mA in two beams and peak luminosity of 8.3×10 cms. The maximum power delivered to the beam via a ceramic vacuum RF window is 260 kW. The maximum HOM power absorbed by the ferrite HOM loads is 5.7 kW per cavity. The commissioning results and operating experience are discussed. During the same time period Cornell has continued basic SRF studies of cavity performance limitations and development of new techniques and tools for experiments, data analysis and computer simulations.