A novel approach to determine photon polarization at collider experiments

The polarization of final-state photons is a critical observable for probing the fundamental mechanisms of particle and nuclear interactions, providing insights into spin and parity structure that are inaccessible through cross-section measurements alone. However, this observable remains largely unexplored in collider experiments, as general-purpose spectrometers traditionally lack the capability to measure it. This paper proposes a novel technique to integrate photon polarimeter function into such a spectrometer without compromising the spectrometer's conventional performance. Key factors to enhance the polarimeter capability are investigated. This successful integration represents the first implementation of a photon polarimeter within a general-purpose spectrometer, establishing a valuable benchmark for the existing and future experiments. The ability to concurrently measure spin polarization and four-momentum data opens a new dimension for analysis, promising a more profound understanding of the underlying physics.