Generation of positrons via pair-creation from Compton scattered gamma-rays

An important role of positron (e+) polarization in future linear colliders is discussed in terms of effective polarization, which is closely related to the clear observation of interesting reaction processes in e−e+ collisions. In order to verify our proposed method, in which highly polarized e+ can be generated through Compton scattering of laser light off a relativistic electron (e−) beam, we performed an experiment to prove the principle and observed e+ productions for the first time. It was found that the production rates of e+ are not only consistent with those of e− and γ-ray but also in good agreement with numerical estimations.