Optimal laser focusing for positron production in laser–electron scattering

Laser–electron beam collisions that aim to generate electron–positron pairs require laser intensities I ≳ 1021 W cm−2, which can be obtained by focusing a 1-PW optical spot smaller than 10 μm. Spatial synchronization is challenge because of the Poynting instability concern both for interacting electron (if laser-generated) and scattering laser. One strategy overcome this problem use an coming from accelerator (e.g., planned E-320 experiment at FACET-II). Even using stable beam, plane wave approximation too simplistic describe laser–electron scattering. This work extends analytical scaling laws pair production, previously derived case short beam. We consider focused colliding with beams different shapes sizes. The results take spatial temporal interaction into account, extended arbitrary shapes, prescribe optimization strategies near-future experiments.