标题： 通过物质中的电磁簇射实现实验室电子-正电子等离子体 显示英文标题

标题： Towards Laboratory Electron-Positron Plasma via Electromagnetic Showers in Matter

摘要： 描述高能电子束与靶材相互作用产生的电磁级联的运动方程被求解，基于在[Phys. Rev. Lett. 134, 135001 (2025)]中发展出的分析框架。 通过目标厚度L与辐射长度Lr之比定义了两种情况，后者取决于电子能量和靶材组成。 对于薄靶（L < Lr），我们推导出了产生的光子和正负电子对的谱以及正负电子对的数量的显式表达式。 对于厚靶（L > Lr），我们得到了总的正负电子对数量和光子谱。 分析结果与Geant4模拟很好地吻合，显示显著的正负电子对逃逸需要L < Lr。 获得了逃逸正负电子对喷流的发散度、密度和特征尺寸，并推导出了一种正负电子等离子体形成的判据。 尽管当前的激光尾波场束流适应性不强，但多拍瓦激光器可能提供新的适用于实验室正负电子等离子体生产的电子或光子源，从而开辟研究极端等离子体天体物理学的新途径。 显示英文摘要

摘要： The kinetic equations describing electromagnetic showers from high-energy electron beams interacting with targets are solved, building on the analytical framework developed in [Phys. Rev. Lett. 134, 135001 (2025)]. Two regimes are defined by the ratio of the target thickness L to the radiation length Lr , which depends on the electron energy and target composition. For thin targets (L < Lr ), we derive explicit expressions for the spectra of produced photons and pairs, as well as the number of pairs. For thick targets (L>Lr ), we obtain the total pair number and photon spectrum. Analytical results agree well with Geant4 simulations, which show that significant pair escape requires L<Lr . The divergence, density and characteristic dimensions of the escaping pair jets are obtained, and a criterion for pair plasma formation is derived. While current laser wakefield beams are not well adapted, multi-petawatt lasers may provide new electron or photon sources suitable for laboratory pair plasma production, opening new avenues for studying extreme plasma astrophysics in the laboratory.