We present high-statistics, precision measurements of the detailed time and energy dependence of the primary cosmic-ray electron flux and positron flux over 79 Bartels rotations from May 2011 to May 2017 in the energy range from 1 to 50 GeV. For the first time, the charge-sign dependent modulation during solar maximum has been investigated in detail by leptons alone. Based on 23.5 x 10(6) events, we report the observation of short-term structures on the timescale of months coincident in both the electron flux and the positron flux. These structures are not visible in the e(+)/e(-) flux ratio. The precision measurements across the solar polarity reversal show that the ratio exhibits a smooth transition over 830 +/- 30 days from one value to another. The midpoint of the transition shows an energy dependent delay relative to the reversal and changes by 260 +/- 30 days from 1 to 6 GeV.

Observation of Complex Time Structures in the Cosmic-Ray Electron and Positron Fluxes with the Alpha Magnetic Spectrometer on the International Space Station

Castellini G;
2018

Abstract

We present high-statistics, precision measurements of the detailed time and energy dependence of the primary cosmic-ray electron flux and positron flux over 79 Bartels rotations from May 2011 to May 2017 in the energy range from 1 to 50 GeV. For the first time, the charge-sign dependent modulation during solar maximum has been investigated in detail by leptons alone. Based on 23.5 x 10(6) events, we report the observation of short-term structures on the timescale of months coincident in both the electron flux and the positron flux. These structures are not visible in the e(+)/e(-) flux ratio. The precision measurements across the solar polarity reversal show that the ratio exhibits a smooth transition over 830 +/- 30 days from one value to another. The midpoint of the transition shows an energy dependent delay relative to the reversal and changes by 260 +/- 30 days from 1 to 6 GeV.
2018
Istituto di Fisica Applicata - IFAC
DARK MATTER
cosmic rays
positron fraction
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.14243/345402
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