Abstract At ground level, the azimuthal distribution of muons in inclined Extensive Air Showers (EAS) is asymmetric, mainly due to geometric effects. Several EAS observables sensitive to the primary particle mass, are constructed after mapping the density of secondary particles from the ground plane to the shower plane (perpendicular to the shower axis). A simple orthogonal projection of the muon coordinates onto this plane distorts the azimuthal symmetry in the shower plane. Using CORSIKA simulations, we correct for this distortion by projecting each muon onto the normal plane following its incoming direction, taking also into account the attenuation probability. We show that besides restoring the azimuthal symmetry of muons density around the shower axis, the application of this procedure has a significant impact on the reconstruction of the distribution of the muon production depth and of its maximum, X max μ , which is an EAS observable sensitive to the primary particle mass. Our results qualitatively suggest that not including it in the reconstruction process of X max μ may introduce a bias in the results obtained by analyzing the actual data on the basis of Monte Carlo simulations.

中文翻译：

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延长空气簇射中μ子密度方位角对称性的恢复

摘要 在地面，倾斜的大范围空气阵雨（EAS）中μ子的方位角分布是不对称的，主要是由于几何效应。几个对初级粒子质量敏感的 EAS 观测值是在将次级粒子的密度从地平面映射到淋浴平面（垂直于淋浴轴）之后构建的。μ子坐标在该平面上的简单正交投影会扭曲淋浴平面中的方位对称性。使用 CORSIKA 模拟，我们通过将每个 μ 子按照其传入方向投影到法线平面上来校正这种失真，同时还考虑了衰减概率。我们表明，除了恢复围绕淋浴轴的 μ 子密度的方位对称性之外，该程序的应用对 μ 子产生深度及其最大值 X max μ 分布的重建具有重大影响，X max μ 是对初级粒子质量敏感的 EAS 可观测值。我们的结果定性地表明，在 X max μ 的重建过程中不包括它可能会在通过分析基于蒙特卡罗模拟的实际数据获得的结果中引入偏差。