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arXiv 2303.09889astro-ph.HE
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利用 KASCADE 实验地面探测到的空气簇射粒子方位角涨落研究膝折处的宇宙射线质量成分

Cosmic ray mass composition at the knee using azimuthal fluctuations of air shower particles detected at ground by the KASCADE experiment

Nicusor Arsene

AI总结:

本研究证明 $LCm$ 参数可作为 KASCADE 实验中宇宙射线质量成分的有效鉴别器,发现重核在膝折处占主导且与多种天体物理模型相符,为 LHAASO 实验提供了重要分析工具。

摘要:

在垂直空气簇射中,强子次级簇射的存在会导致地面粒子分布的方位角非均匀性。$LCm$ 参数用于量化在簇射轴周围给定距离的圆环上探测器记录信号的非均匀性,已成功作为 PeV 能量下的伽马/强子鉴别器被引入。在本研究中,我们证明了 $LCm$ 参数在采用紧凑探测器阵列(如 KASCADE)的实验中,可以有效地作为质量成分鉴别器。我们利用 KASCADE 实验的测量数据,在 $\lg(E/\rm eV) = [15.0 \text{ - } 16.0]$ 能量范围内重建了 $LCm$ 参数分布,步长为 $\lg(E/\rm eV) = 0.2$;随后考虑了三种强子相互作用模型:QGSjet-II-04、EPOS-LHC 和 SIBYLL 2.3d,并使用五种初级原子核种类(p、He、C、Si 和 Fe)的 MC 模板对其进行了拟合。我们发现 $LCm$ 参数对所考虑的具体强子相互作用模型表现出极小的依赖性。重建的单个核素比例表明,随着能量增加,质子和 He 核的丰度呈线性下降,而正如所有三种强子相互作用模型所预测的那样,较重成分在膝折(knee)之上变得占主导地位。我们的研究结果表明,粒子类型的丰度作为能量的函数,与将膝折与银河系内宇宙射线的加速和传播联系起来的不同天体物理模型相一致。此外,它们还表现出与另外三种较新的数据驱动天体物理模型的极好一致性。这些发现表明,$LCm$ 参数可以成为 LHAASO 实验未来测量的宝贵工具,以增进我们对宇宙射线起源和加速机制的认识。

英文摘要:

The presence of hadronic sub-showers causes azimuthal non-uniformity in the particle distributions on the ground in vertical air showers. The $LCm$ parameter, which quantifies the non-uniformity of the signal recorded in detectors located at a given distance on a ring around the shower axis, has been successfully introduced as a gamma/hadron discriminator at PeV energies \cite{Conceicao:2022lkc}. In this work, we demonstrate that the $LCm$ parameter can effectively serve as a mass composition discriminator in experiments that employ a compact array of detectors, like KASCADE. We reconstruct the $LCm$ parameter distributions in the energy range $\lg(E/\rm eV) = [15.0 \text{ - } 16.0]$ using measurements from the KASCADE experiment, with intervals of $\lg(E/\rm eV) = 0.2$, which are then fitted with MC templates for five primary nuclei species p, He, C, Si, and Fe considering three hadronic interaction models: QGSjet-II-04, EPOS-LHC and SIBYLL 2.3d. We find that the $LCm$ parameter exhibits minimal dependence on the specific hadronic interaction model considered. The reconstructed fractions of individual species demonstrate a linear decrease in the abundance of protons and He nuclei with increasing energy, while the heavier components become prevalent above the \textit{knee} as predicted by all three hadronic interaction models. Our findings indicate that the abundance of particle types as a function of energy aligns with different astrophysical models that link the \textit{knee} to the acceleration and propagation of cosmic rays within the Galaxy. Furthermore, they also demonstrate excellent agreement with three more recent data-driven astrophysical models. These findings suggest that the $LCm$ parameter could be a valuable tool for forthcoming measurements of the LHAASO experiment to enhance our knowledge about the origin and acceleration mechanisms of cosmic rays.

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