Polarized positron source for the linear collider, JLC

A comprehensive description of a polarized positron project is presented in terms of physics motivations for utilizing a polarized positron in electron–positron collider experiments, a proof-of-principle experiment and a conceptual design of a polarized positron source for the future linear collider JLC. In order to verify a proposed method of creating highly polarized positron beams via successive two fundamental processes, i.e. Compton scattering and pair creation, we have been performing basic experiments both at KEK and BNL. First observation of positrons was made at KEK using an electron beam of 1.26 GeV and a laser of 2.33 eV. High-intensity picosecond X-rays were also generated at BNL using a specially designed Compton chamber. In order to realize polarized positron beams of the JLC which have considerably high intensity, i.e. 0.7×1010 e+/pulse and a complicated multi-bunch structure, we have achieved a possible scheme for the Compton scattering system and a positron capture section into an L-band linac.