The cosmic-ray electron and positron spectrum measured with CALET on the International Space Station

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https://doi.org/10.22323/1.444.0071
 http://hdl.handle.net/11603/36423

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UMBC Center for Space Sciences and Technology (CSST) / Center for Research and Exploration in Space Sciences & Technology II (CRSST II)
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https://orcid.org/0000-0003-2916-6955
 https://orcid.org/0000-0002-9247-3010

Date

2023-08-18

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conference papers and proceedings
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Oscar Adriani, Yosui Akaike, Katsuaki Asano, Yoichi Aaoka, Eugenio Berti, Gabriele Bigongiari, et al. “The Cosmic-Ray Electron and Positron Spectrum Measured with CALET on the International Space Station.” In Proceedings of 38th International Cosmic Ray Conference — PoS(ICRC2023), 444:071. SISSA Medialab, 2023. https://doi.org/10.22323/1.444.0071.

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This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
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Abstract

The CALorimetric Electron Telescope (CALET) has been collecting data on the International Space Station for more than seven years since October 2015. CALET is an all-calorimetric instrument with a total vertical thickness of 30 radiation lengths and fine imaging capability, optimized for the measurement of the electron and positron (all-electron) spectrum well into the TeV energy region. The observed event statistics have increased more than three times since its last publication about the all-electron spectrum to 4.8 TeV in 2018. Based on Monte Carlo simulations, the data analysis effectively rejects background protons, resulting in less than 10% contamination up to the TeV region. The expected systematic errors are investigated. The significance of the cutoff at the TeV region in the energy spectrum, which is expected as a result of radiation loss during propagation, has increased to over 6σ. By observing the detailed structure in the TeV region of the energy spectrum, we will investigate on the presence of possible nearby cosmic-ray sources. In this paper, we will present the updated all-electron spectrum, and briefly discuss its interpretations.