Iron and nickel cosmic ray nuclei play a key role in the understanding of the acceleration and propagation mechanisms of charged particles in our Galaxy. In fact, iron and nickel are the most abundant nuclei among the heavy elements and provide favorable conditions for a low background measurement thanks to the negligible contamination from spallation of higher mass elements. CALET, operating on the ISS since 2015, has excellent capabilities of charge discrimination up to nickel and can measure the energy of cosmic ray nuclei thanks to a lead tungstate calorimeter providing a direct and precise measurement of heavy charged nuclei spectra. In this contribution, a direct measurement of iron and nickel nuclei spectra in the energy range from 10 GeV/n to 2 TeV/n and from 8.8 GeV/n to 240 GeV/n, respectively is presented. More than five years of data collected by CALET were used. A detailed study of systematic uncertainties is also illustrated. The measured spectra are compared with the ones measured by other experiments and are compatible with a single power law fit in the energy region from 50 GeV/n to 2 TeV/n and from 20 GeV/n to 240 GeV/n for iron and nickel respectively. Also, the ratio between nickel and iron spectra is reported.

中文翻译：

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在国际空间站上使用 CALET 直接测量宇宙射线铁和镍

铁和镍宇宙线核在理解银河系带电粒子的加速和传播机制方面发挥着关键作用。事实上，铁和镍是重元素中最丰富的原子核，并且由于较高质量元素散裂造成的污染可以忽略不计，因此为低背景测量提供了有利的条件。 CALET 自 2015 年起在国际空间站上运行，具有出色的镍电荷辨别能力，并且可以测量宇宙射线核的能量，这要归功于铅钨酸盐热量计，可直接、精确地测量重带电核光谱。在这篇文章中，提出了对能量范围分别为 10 GeV/n 至 2 TeV/n 和 8.8 GeV/n 至 240 GeV/n 的铁和镍原子核光谱的直接测量。使用了 CALET 收集的五​​年多的数据。还阐述了对系统不确定性的详细研究。将测得的光谱与其他实验测得的光谱进行比较，并且与铁和镍的 50 GeV/n 至 2 TeV/n 以及 20 GeV/n 至 240 GeV/n 能量区域内的单一幂律拟合兼容分别。此外，还报告了镍和铁光谱之间的比率。