Top panel: mean particle Lorentz factor at ω_pet = 7840 for σ₀ = 30. Middle panels: electron and positron x–p_x phase-space distribution dN/dxdydp_x along the midplane integrated within y/d_e ± 75. Bottom panels: local particle spectra measured at four locations shown in the top panel and labeled from ① to ④. The dashed line is the total spectrum, and the dotted line is dN/du ∝ u^−2.2 for reference.