Abstract
Precision results on cosmic-ray electrons are presented in the energy range from 0.5GeV to 1.4TeV based on 28.1×10^{6} electrons collected by the Alpha Magnetic Spectrometer on the International Space Station. In the entire energy range the electron and positron spectra have distinctly different magnitudes and energy dependences. The electron flux exhibits a significant excess starting from 42.1_{-5.2}^{+5.4} GeV compared to the lower energy trends, but the nature of this excess is different from the positron flux excess above 25.2±1.8 GeV. Contrary to the positron flux, which has an exponential energy cutoff of 810_{-180}^{+310} GeV, at the 5σ level the electron flux does not have an energy cutoff below 1.9TeV. In the entire energy range the electron flux is well described by the sum of two power law components. The different behavior of the cosmic-ray electrons and positrons measured by the Alpha Magnetic Spectrometer is clear evidence that most high energy electrons originate from different sources than high energy positrons.
Highlights
Precision results on cosmic-ray electrons are presented in the energy range from 0.5 GeV to 1.4 TeV based on 28.1 × 106 electrons collected by the Alpha Magnetic Spectrometer on the International Space Station
GeV compared to the lower energy trends, but the nature of this excess is different from the positron flux excess above 25.2 Æ 1.8 GeV
The different behavior of the cosmic-ray electrons and positrons measured by the Alpha Magnetic Spectrometer is clear evidence that most high energy electrons originate from different sources than high energy positrons
Summary
Precision results on cosmic-ray electrons are presented in the energy range from 0.5 GeV to 1.4 TeV based on 28.1 × 106 electrons collected by the Alpha Magnetic Spectrometer on the International Space Station. The precision measurement of the electron flux in primary cosmic rays with the Alpha Magnetic Spectrometer (AMS) on the International Space Station (ISS) is presented with a particular emphasis on the behavior at high energies. In this Letter we present precision measurements of primary cosmic-ray electrons up to 1.4 TeV and the comparison with our latest data on cosmicray positrons [4]. To reduce the statistical fluctuation, the charge confusion proton template is constructed using proton data This is done by selecting protons with the TRD and the tracker, and requiring the ratio of the ECAL energy and the tracker rigidity E=jRj < 1.0. Data analysis.—The isotropic electron flux for the energy bin Ei of width ΔEi is given by
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