Precision Measurement of the Helium Flux in Primary Cosmic Rays of Rigidities 1.9 GV to 3 TV with the Alpha Magnetic Spectrometer on the International Space Station.
Precision Measurement of the Helium Flux in Primary Cosmic Rays of Rigidities 1.9 GV to 3 TV with the Alpha Magnetic Spectrometer on the International Space Station.
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DOI：
10.1103/physrevlett.115.211101
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发表时间：
2015-11
影响因子：
8.6
通讯作者：
M. Aguilar;D. Aisa;B. Alpat;A. Alvino;G. Ambrosi;K. Andeen;L. Arruda;N. Attig;P. Azzarello
中科院分区：
文献类型：
--
作者：
M. Aguilar;D. Aisa;B. Alpat;A. Alvino;G. Ambrosi;K. Andeen;L. Arruda;N. Attig;P. Azzarello
氦通量的精确刚性依赖的知识对于理解宇宙射线的起源、加速和传播是重要的。本文提出了一种基于5000万次事件的、刚性（动量/电荷）从1.9 GV到3 TV的初宇宙线氦通量的精确测量方法，并与质子通量进行了比较。首次给出了氦通量谱指数随刚度的详细变化规律。当刚度大于100 GV时，光谱指数逐渐变硬。氦通量谱指数的刚度依赖性与质子谱指数相似，只是量级不同。值得注意的是，质子氦通量比的光谱指数随着刚度的增加而增加，直到45 GV后才趋于恒定；45 GV以上的通量比可以用一个幂律很好地描述。
Knowledge of the precise rigidity dependence of the helium flux is important in understanding the origin, acceleration, and propagation of cosmic rays. A precise measurement of the helium flux in primary cosmic rays with rigidity (momentum/charge) from 1.9 GV to 3 TV based on 50 million events is presented and compared to the proton flux. The detailed variation with rigidity of the helium flux spectral index is presented for the first time. The spectral index progressively hardens at rigidities larger than 100 GV. The rigidity dependence of the helium flux spectral index is similar to that of the proton spectral index though the magnitudes are different. Remarkably, the spectral index of the proton to helium flux ratio increases with rigidity up to 45 GV and then becomes constant; the flux ratio above 45 GV is well described by a single power law.