论文标题
在单眼模式下观察到的2个PEV和2个EEV之间的宇宙射线组成
The Cosmic-Ray Composition between 2 PeV and 2 EeV Observed with the TALE Detector in Monocular Mode
论文作者
论文摘要
我们报告了望远镜阵列低能扩展（Tale）空气荧光检测器（FD）对宇宙射线组成的测量。通过使用Cosmic Ray（CR）引起的大量空气淋浴的空气荧光除了使用Cherenkov光信号，故事FD可以测量具有低至$ \ sim 2 $ PEV并超过1 EEV的宇宙射线的性质。在本文中，我们介绍了$ x _ {\ rm max} $在此能量范围内观察到的淋浴的分布的结果。本研究分析了在$ \ sim 4 $年内收集的数据。将所得的$ x _ {\ rm max} $分布与蒙特卡洛（MC）模拟数据分布进行比较，用于具有不同组成的主宇宙射线，并执行了4组分拟合。对能量箱进行比较和拟合，在$ \ log_ {10}（e/{\ rm eV}）$中，宽度为0.1或0.2，跨越了测得的能量的全部范围。我们还检查了平均$ x _ {\ rm max} $值作为能量大于$ 10^{15.8} $ ev的宇宙射线的能量的函数。低于$ 10^{17.3} $ eV，数据的平均$ x _ {\ rm max} $作为数据的函数（伸长率）的函数明显小于模型中所有元素的斜率，这表明该能源在能量范围内随着能量而变得更重。这与银河源事件的刚性截止量是一致的。最后，在$ 10^{17} $ eV以上的能量上观察到$ x _ {\ rm max} $伸长率的增加，这表明宇宙射线构图发生了另一种变化。
We report on a measurement of the cosmic ray composition by the Telescope Array Low-Energy Extension (TALE) air fluorescence detector (FD). By making use of the Cherenkov light signal in addition to air fluorescence light from cosmic ray (CR) induced extensive air showers, the TALE FD can measure the properties of the cosmic rays with energies as low as $\sim 2$ PeV and exceeding 1 EeV. In this paper, we present results on the measurement of $X_{\rm max}$ distributions of showers observed over this energy range. Data collected over a period of $\sim 4$ years was analyzed for this study. The resulting $X_{\rm max}$ distributions are compared to the Monte Carlo (MC) simulated data distributions for primary cosmic rays with varying composition and a 4-component fit is performed. The comparison and fit are performed for energy bins, of width 0.1 or 0.2 in $\log_{10} (E/{\rm eV})$, spanning the full range of the measured energies. We also examine the mean $X_{\rm max}$ value as a function of energy for cosmic rays with energies greater than $10^{15.8}$ eV. Below $10^{17.3}$ eV, the slope of the mean $X_{\rm max}$ as a function of energy (the elongation rate) for the data is significantly smaller than that of all elements in the models, indicating that the composition is becoming heavier with energy in this energy range. This is consistent with a rigidity-dependent cutoff of events from galactic sources. Finally, an increase in the $X_{\rm max}$ elongation rate is observed at energies just above $10^{17}$ eV indicating another change in the cosmic rays composition.
