Properties of Neon, Magnesium, and Silicon Primary Cosmic Rays Results from the Alpha Magnetic Spectrometer

Abstract

We report the observation of new properties of primary cosmic rays, neon (Ne), magnesium (Mg), and silicon (Si), measured in the rigidity range 2.15 GV to 3.0 TV with $1.8\times10^6$  Ne, $2.2\times10^6$  Mg, and $1.6\times10^6$  Si nuclei collected by the Alpha Magnetic Spectrometer experiment on the International Space Station. The Ne and Mg spectra have identical rigidity dependence above 3.65 GV. The three spectra have identical rigidity dependence above 86.5 GV, deviate from a single power law above 200 GV, and harden in an identical way. Unexpectedly, above 86.5 GV the rigidity dependence of primary cosmic rays Ne, Mg, and Si spectra is different from the rigidity dependence of primary cosmic rays He, C, and O. This shows that the Ne, Mg, and Si and He, C, and O are two different classes of primary cosmic rays.

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The Ne flux $\Phi$ as a function of rigidity at the top of AMS in units of $[{\rm m}^2 \cdot {\rm sr} \cdot {\rm s} \cdot {\rm GV}]^{-1}$ including errors due to statistics (stat.); contributions to the systematic error from the trigger and acceptance (acc.); the rigidity resolution function and unfolding (unf.); the absolute rigidity scale (scale); and the total systematic error (syst.). The contribution of individual sources to the systematic error are added in quadrature to arrive at the total systematic error.
 

The Mg flux $\Phi$ as a function of rigidity at the top of AMS in units of $[{\rm m}^2 \cdot {\rm sr} \cdot {\rm s} \cdot {\rm GV}]^{-1}$ including errors due to statistics (stat.); contributions to the systematic error from the trigger, acceptance, and background (acc.); the rigidity resolution function and unfolding (unf.); the absolute rigidity scale (scale); and the total systematic error (syst.). The contribution of individual sources to the systematic error are added in quadrature to arrive at the total systematic error.

The Si flux $\Phi$ as a function of rigidity at the top of AMS in units of $[{\rm m}^2 \cdot {\rm sr} \cdot {\rm s} \cdot {\rm GV}]^{-1}$ including errors due to statistics (stat.); contributions to the systematic error from the trigger, acceptance, and background (acc.); the rigidity resolution function and unfolding (unf.); the absolute rigidity scale (scale); and the total systematic error (syst.). The contribution of individual sources to the systematic error are added in quadrature to arrive at the total systematic error.

The neon to magnesium flux ratio Ne/Mg as a function of rigidity including errors due to statistics (stat.); contributions to the systematic error from the trigger, acceptance, and background (acc.); the rigidity resolution function and unfolding (unf.); the absolute rigidity scale (scale); and the total systematic error (syst.). The statistical errors are the sum in quadrature of the ratios of neon and magnesium flux statistical errors to the corresponding flux values, multiplied by the Ne/Mg flux ratio. The systematic errors from the background subtraction, the trigger, and the event reconstruction and selection are likewise added in quadrature. The correlations in the systematic errors from the uncertainty in nuclear interaction cross sections, the unfolding and the absolute rigidity scale between the neon and magnesium fluxes have been taken into account in calculating the corresponding systematic errors of the Ne/Mg flux ratio. The contribution of individual sources to the systematic error are added in quadrature to arrive at the total systematic uncertainty.
 

The silicon to magnesium flux ratio Si/Mg as a function of rigidity including errors due to statistics (stat.); contributions to the systematic error from the trigger, acceptance, and background (acc.); the rigidity resolution function and unfolding (unf.); the absolute rigidity scale (scale); and the total systematic error (syst.). The statistical errors are the sum in quadrature of the ratios of silicon and magnesium flux statistical errors to the corresponding flux values, multiplied by the Si/Mg flux ratio. The systematic errors from the background subtraction, the trigger, and the event reconstruction and selection are likewise added in quadrature. The correlations in the systematic errors from the uncertainty in nuclear interaction cross sections, the unfolding and the absolute rigidity scale between the silicon and magnesium fluxes have been taken into account in calculating the corresponding systematic errors of the Si/Mg flux ratio. The contribution of individual sources to the systematic error are added in quadrature to arrive at the total systematic uncertainty.
 

The neon to oxygen flux ratio Ne/O as a function of rigidity including errors due to statistics (stat.); contributions to the systematic error from the trigger, acceptance, and background (acc.); the rigidity resolution function and unfolding (unf.); the absolute rigidity scale (scale); and the total systematic error (syst.). The statistical errors are the sum in quadrature of the ratios of neon and oxygen flux statistical errors to the corresponding flux values, multiplied by the Ne/O flux ratio. The systematic errors from the background subtraction, the trigger, and the event reconstruction and selection are likewise added in quadrature. The correlations in the systematic errors from the uncertainty in nuclear interaction cross sections, the unfolding and the absolute rigidity scale between the neon and oxygen fluxes have been taken into account in calculating the corresponding systematic errors of the Ne/O flux ratio. The contribution of individual sources to the systematic error are added in quadrature to arrive at the total systematic uncertainty.
 

The magnesium to oxygen flux ratio Mg/O as a function of rigidity including errors due to statistics (stat.); contributions to the systematic error from the trigger, acceptance, and background (acc.); the rigidity resolution function and unfolding (unf.); the absolute rigidity scale (scale); and the total systematic error (syst.). The statistical errors are the sum in quadrature of the ratios of magnesium and oxygen flux statistical errors to the corresponding flux values, multiplied by the Mg/O flux ratio. The systematic errors from the background subtraction, the trigger, and the event reconstruction and selection are likewise added in quadrature. The correlations in the systematic errors from the uncertainty in nuclear interaction cross sections, the unfolding and the absolute rigidity scale between the magnesium and oxygen fluxes have been taken into account in calculating the corresponding systematic errors of the Mg/O flux ratio. The contribution of individual sources to the systematic error are added in quadrature to arrive at the total systematic uncertainty.
 

The silicon to oxygen flux ratio Si/O as a function of rigidity including errors due to statistics (stat.); contributions to the systematic error from the trigger, acceptance, and background (acc.); the rigidity resolution function and unfolding (unf.); the absolute rigidity scale (scale); and the total systematic error (syst.). The statistical errors are the sum in quadrature of the ratios of silicon and oxygen flux statistical errors to the corresponding flux values, multiplied by the Si/O flux ratio. The systematic errors from the background subtraction, the trigger, and the event reconstruction and selection are likewise added in quadrature. The correlations in the systematic errors from the uncertainty in nuclear interaction cross sections, the unfolding and the absolute rigidity scale between the silicon and oxygen fluxes have been taken into account in calculating the corresponding systematic errors of the Si/O flux ratio. The contribution of individual sources to the systematic error are added in quadrature to arrive at the total systematic uncertainty.
 

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