Lattice layout and linear optics for sharing superconducting linac

Abstract

A superconducting (SC) linac allows a few orders of magnitude larger average beam current than a normal conducting linac, therefore the powerful beam is expected to lead to outstanding discoveries in various scientific fields, such as high luminosity accelerators and high brilliance light source. However, the high construction and operation costs of the SC linac is a critical issue for realizing large scale facilities. To resolve this problem, we propose a continuous wave (cw) operation of an SC linac shared by electron/ positron beams for effective multipurpose utilization. A high current positron source is required for high-energy physics projects: a linear electron-positron collider and a muon collider, while high-current and high-quality electron beams are expected to realize the high brilliant x-ray light sources. As an example, we discuss the injector of the International Linear Collider, an x-ray free-electron laser, and an energy-recovery linac light source. We found a feasible solution of a basic design for the proposed multibeam operation despite the high-quality beam requirements and complicated operation: control of mixed beams without pulsed magnets, and heat load in the cavity, high stability of beam energy, and operation at high average current.