We analyze recent AMS-02 comic-ray measurements of Lithium, Beryllium, Boron, Carbon, Nitrogen and Oxygen. The emphasis of the analysis is on systematic uncertainties related to propagation and nuclear cross sections. To investigate the uncertainties in the propagation scenario, we consider five different frameworks, differing with respect to the inclusion of a diffusion break at a few GV, the presence of reacceleration, and the presence of a break in the injection spectra of primaries. For each framework we fit the diffusion equations of cosmic rays and explore the parameter space with Monte Carlo methods. At the same time, the impact of the uncertainties in the nuclear production cross sections of secondaries is explicitly considered and included in the fit through the use of nuisance parameters. We find that all the considered frameworks are able to provide a good fit. In particular, two competing scenarios, one including a break in diffusion but no reacceleration and the other with reacceleration but no break in diffusion are both allowed. The inclusion of cross-section uncertainties is, however, crucial, to this result. Thus, at the moment, these uncertainties represent a fundamental systematic preventing a deeper understanding of the properties of CR propagation. We find, nonetheless, that the slope of diffusion at intermediate rigidities is robustly constrained in the range $δ\simeq0.45-0.5$ in models without convection, or $δ\simeq0.4-0.5$ if convection is included in the fit. Furthermore, we find that the use of the AMS-02 Beryllium data provides a lower limit on the vertical size of the Galactic propagation halo of $z_\mathrm{h}\gtrsim3$ kpc.
Precision Measurement of Boron-to-Carbon ratio in Cosmic Rays from 2 GV to 2 TV with the Alpha Magnetic Spectrometer on the International Space Station
AMS-02是2011年5月安装在国际空间站上的一个被广泛接受的高能物理实验，自那时以来一直在持续运行。AMS-02能够分离污染小于$10^{-3}$的宇宙射线轻核（$1\leq Z \leq 8$）。宇宙射线硼和碳通量之间的比率已知对宇宙射线在银河系中的传播特性非常敏感，因为硼是在星际介质上的较重的主要元素如碳和氧的次级产物。达到TeV区域的精确测量可以极大地帮助理解宇宙射线在银河系中的传播以及到达地球之前穿过的物质数量。介绍了基于1000万次硼碳事件的硼碳比测量的现状。
Direct Measurement of the Cosmic-Ray Carbon and Oxygen Spectra from 10 GeV$/n$ to 2.2 TeV$/n$ with the Calorimetric Electron Telescope on the International Space Station
在本文中，我们介绍了基于2015年10月至2019年10月国际空间站上的量热电子望远镜（CALET）观测的宇宙射线中碳和氧的能谱测量。分析，包括系统的不确定性的详细评估，并报告结果。用全量热仪测量了从10 GeV $/n$到2.2 TeV $/n$的能谱，其总厚度对应于1.3核相互作用长度。观测到的碳和氧通量显示出$\sim$ 0.15的光谱指数变化约200 GeV的$/n$建立了一个显着的$>3σ$。它们具有相同的能量依赖性与恒定的C/O通量比$0.911\pm 0.006$以上的25 GeV $/n$。光谱硬化与AMS-02测量的一致，但通量的绝对归一化约低27%，尽管与包括PAMELA光谱仪和热气球实验CREAM在内的先前实验的观测结果一致。
