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arXiv · 2508.16220

Generating Cylindrical Vector γ Rays via Beam-Target Interactions: Towards Structured Light at High Energies

Yue Cao·Kun Xue·Si-Man Liu·Zhong-Peng Li·Li-Xiang Hu·Xin-Yu Liu·Zhen-Ke Dou·Feng Wan·Qian Zhao·Tong-Pu Yu·Jian-Xing Li
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Abstract

Structured γ rays, particularly cylindrical vector γ rays, offer promising tools for sub-nuclear imaging and polarization-sensitive probes in fundamental research and applications, but conventional optical methods face great challenges at such photon energy. Here, we put forward a novel method generating such γ rays through relativistic beam-target interactions. For instance, radially polarized γ rays can be generated by using a dense electron beam striking a multifoil target. We find that the radial polarization is transferred from the generated coherent transition radiation (CTR) fields to $γ$ photons through nonlinear Compton scattering, with the high polarization preserved by phase matching. Three-dimensional spin-resolved simulations demonstrate radial polarization degrees approaching 60\%. Furthermore, these γ rays can decay into azimuthally spin-polarized positrons via the nonlinear Breit-Wheeler process, with their spins aligning along the CTR magnetic field. Our work extends the concept of structured light into the γ-ray regime, offering new prospects for broad fields such as nuclear structure probing, fundamental symmetries tests, polarization-sensitive studies in extreme conditions, and laboratory astrophysical observations.

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Yue Cao, Kun Xue, Si-Man Liu, Zhong-Peng Li, Li-Xiang Hu, Xin-Yu Liu, Zhen-Ke Dou, Feng Wan, Qian Zhao, Tong-Pu Yu, Jian-Xing Li. 2025-08-22. Generating Cylindrical Vector γ Rays via Beam-Target Interactions: Towards Structured Light at High Energies. https://arxiv.org/abs/2508.16220

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