Periodicities in the Daily Proton Fluxes from 2011 to 2019 Measured by the Alpha Magnetic Spectrometer on the International Space Station from 1 to 100 GV

We present the precision measurement of the daily proton fluxes in cosmic rays from May 20, 2011 to October 29, 2019 (a total of 2824 days or 114 Bartels rotations) in the rigidity interval from 1 to 100 GV based on 5.5 x 10(9) protons collected with the Alpha Magnetic Spectrometer aboard the International Space Station. The proton fluxes exhibit variations on multiple timescales. From 2014 to 2018, we observed recurrent flux variations with a period of 27 days. Shorter periods of 9 days and 13.5 days are observed in 2016. The strength of all three periodicities changes with time and rigidity. The rigidity dependence of the 27-day periodicity is different from the rigidity dependences of 9-day and 13.5-day periods. Unexpectedly, the strength of 9-day and 13.5-day periodicities increases with increasing rigidities up to similar to 10 GV and similar to 20 GV, respectively. Then the strength of the periodicities decreases with increasing rigidity up to 100 GV.

Automated summary

This study presents a precision measurement of daily proton fluxes in cosmic rays from May 20, 2011 to October 29, 2019 based on data collected by the Alpha Magnetic Spectrometer aboard the International Space Station. The proton fluxes exhibit variations on multiple time scales, with recurrent flux variations of 27 days observed from 2014 to 2018, and shorter periods of 9 days and 13.5 days observed in 2016. The strength of these periodicities changes with time and rigidity, with unexpected increases in strength up to certain rigidities followed by decreases as rigidity further increases.