First systematic experimental 2D mapping of linearly polarized γ -ray polarimetric distributions in relativistic Compton scattering

The interaction of photons with relativistic electrons constitutes a fundamental electromagnetic process whose polarization-transfer mechanics remain incompletely characterized. We report the first systematic measurement of the spatial polarization distribution for [Formula: see text] rays generated via [Formula: see text] slant inverse Compton scattering (ICS) between linearly polarized [Formula: see text] photons and [Formula: see text] electrons, performing full two-dimensional mapping of the intensity, angle of polarization (AOP) and degree of polarization (DOP). The measurements reveal an asymmetric beam profile along the laser polarization direction that resembles observations from [Formula: see text] backward ICS. The central beam region exhibits DOP near 1.0, with the AOP rigidly aligned at [Formula: see text], while peripheral regions display complex, non-uniform polarization distributions. These findings confirm quantum electrodynamics predictions of near-complete polarization transfer along the beam axis in slant geometries, thereby establishing slant scattering as a viable alternative to head-on configurations for generating high-DOP [Formula: see text] rays.