Proposed method to produce a highly polarized e(+) beam for future linear colliders

We propose a method to produce a spin-polarized ef beam using e(+)e(-) pair-creation by circularly polarized photons. Assuming Compton scattering of an unpolarized e(-) beam and circularly polarized laser light, scattered gamma-rays at the high end of the energy spectrum are also circularly polarized. If those gamma-rays are utilized to create e(+/-) pairs on a thin target, the spin-polarization is preserved for e(+)'s at the high end of their energy spectrum. By using the injector linac of Accelerator Test Facility at KEK and a commercially available Nd:YAG pulse laser, we can expect about 10(5) polarized e(+)'s per second with a degree of polarization of 80% and a kinetic energy of 35-80 MeV. The apparatus for creation and measurement of polarized e(+)'s is being constructed. We present new idea for possible application of our method to future Linear colliders by utilizing a high-power CO2 laser.