Reducing Energy Spread for Long Bunch Train at SLAC

The normal energy gain of the SLC RF system, using SLED (SLAC Energy Development) cavities, can accelerate only about 150 ns beam pulse within an energy spread of 0.5 % with 1011 particles per pulse. By applying two additional 180o phase inversions for about 20 % of all SLC klystrons, the classical SLED pulse is flattened to achieve an energy spread of 0.5 % over 240 ns which corresponds to 680 bunches in S-band. This scheme was developed for the fixed target experiment E-154, to study the neutron spin. It was used to run at a beam energy of 48.8 GeV and a beam charge of up to 1011 eper pulse. This paper describes the beam loading compensation using early beam injection scheme and new RF phase inversions which have been implemented for the SLED devices. The The normal energy gain of the SLC RF system, using SLED (SLAC Energy experimental results, obtained during fall 1995, are compared to simulations. The results surpassed the initial requested beam qualities. A similar approach might be useful for future linear colliders with long bunch trains. Contributed to Fifth European Particle Accelerator Conference (EPAC 96)) Sitges Barcelona, Spain 10-14 June 1996 * Work supported by Department of Energy contract DE–AC03–76SF00515. REDUCING ENERGY SPREAD FOR LONG BUNCH TRAIN AT SLAC F.-J. Decker, D. Farkas, L. Rinolfi1, J. Truher, SLAC2, California, USA