Linac design for the LCLS project at SLAC

The Linac Coherent Light Source (LCLS) at SLAC is being designed to produce intense, coherent 0.15-nm X-rays. These X-rays will be produced by a single pass of a 15 GeV bunched electron beam through a long undulator. Nominally, the bunches have a charge of 1 nC, normalized transverse emittances of less than 1.5/spl pi/ mm-mr and an rms bunch length of 20 /spl mu/m. The electron beam will be produced using the last third of the SLAC 3-km linac in a manner compatible with simultaneous operation of the remainder of the linac for PEP-II. The linac design necessary to produce an electron beam with the required brightness for LCLS is discussed, and the specific linac modifications are described.