ALICE is a large experiment at the CERN Large Hadron Collider. Located 52 meters underground, its detectors are suitable to measure muons produced by cosmic-ray interactions in the atmosphere. In this paper, the studies of the cosmic muons registered by ALICE during Run 2 (2015–2018) are described. The analysis is limited to multimuon events defined as events with more than four detected muons (N_μ > 4) and in the zenith angle range 0° < θ < 50°. The results are compared with Monte Carlo simulations using three of the main hadronic interaction models describing the air shower development in the atmosphere: QGSJET-II-04, EPOS-LHC, and SIBYLL 2.3d. The interval of the primary cosmic-ray energy involved in the measured muon multiplicity distribution is about 4 × 10¹⁵ < E _prim < 6 × 10¹⁶ eV. In this interval none of the three models is able to describe precisely the trend of the composition of cosmic rays as the energy increases. However, QGSJET-II-04 is found to be the only model capable of reproducing reasonably well the muon multiplicity distribution, assuming a heavy composition of the primary cosmic rays over the whole energy range, while SIBYLL 2.3d and EPOS-LHC underpredict the number of muons in a large interval of multiplicity by more than 20% and 30%, respectively. The rate of high muon multiplicity events (N_μ > 100) obtained with QGSJET-II-04 and SIBYLL 2.3d is compatible with the data, while EPOS-LHC produces a significantly lower rate (55% of the measured rate). For both QGSJET-II-04 and SIBYLL 2.3d, the rate is close to the data when the composition is assumed to be dominated by heavy elements, an outcome compatible with the average energy E _prim ∼ 10¹⁷ eV of these events. This result places significant constraints on more exotic production mechanisms.

中文翻译：

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在 LHC 的 ALICE 中看到的宇宙射线事件中的多子


ALICE 是 CERN 大型强子对撞机的一项大型实验。它的探测器位于地下 52 米处，适用于测量大气中宇宙射线相互作用产生的 μ 子。在本文中，描述了 ALICE 在 Run 2 （2015-2018） 期间记录的宇宙 μ 子的研究。分析仅限于多 μ 子事件，定义为检测到 4 个以上 μ 子 （N_μ > 4） 且天顶角范围 0° < θ < 50° 的事件。使用描述大气中空气淋浴发展的三个主要强子相互作用模型（QGSJET-II-04、EPOS-LHC 和 SIBYLL 2.3d）将结果与蒙特卡洛模拟进行了比较。参与测量的 μ 子多重性分布的初级宇宙射线能量的区间约为 4 × 10¹⁵ < E_prim < 6 × 10¹⁶ eV。在这个区间内，三个模型都无法准确描述随着能量增加而宇宙射线组成的趋势。然而，QGSJET-II-04 被发现是唯一能够合理地再现 μ 子多重性分布的模型，假设整个能量范围内初级宇宙射线的组成很重，而 SIBYLL 2.3d 和 EPOS-LHC 分别低估了大多重性区间中的 μ 子数量超过 20% 和 30%。使用 QGSJET-II-04 和 SIBYLL 2.3d 获得的高 μ 子多重性事件速率 （N_μ > 100） 与数据兼容，而 EPOS-LHC 产生的速率明显较低（测量速率的 55%）。对于 QGSJET-II-04 和 SIBYLL 2.3d，当假设成分以重元素为主时，速率接近数据，这一结果与这些事件的平均能量 E_prim ∼ 10¹⁷ eV 兼容。 这一结果对更奇特的生产机制造成了重大限制。