Direct Measurement of the Spectral Structure of Cosmic-Ray Electrons+Positrons in the TeV Region with CALET on the International Space Station

O Adriani^{1

2}, Y Akaike^{3

4}, K Asano⁵, Y Asaoka⁵, E Berti^{2

6}, G Bigongiari^{7

8}, W R Binns⁹, M Bongi^{1

2}, P Brogi^{7

8}, A Bruno¹⁰, J H Buckley⁹, N Cannady^{11

12

13}, G Castellini⁶, C Checchia^{7

8}, M L Cherry¹⁴, G Collazuol^{15

16}, G A de Nolfo¹⁰, K Ebisawa¹⁷, A W Ficklin¹⁴, H Fuke¹⁷, S Gonzi^{1

2

6}, T G Guzik¹⁴, T Hams¹¹, K Hibino¹⁸, M Ichimura¹⁹, K Ioka²⁰, W Ishizaki⁵, M H Israel⁹, K Kasahara²¹, J Kataoka²², R Kataoka²³, Y Katayose²⁴, C Kato²⁵, N Kawanaka²⁰, Y Kawakubo¹⁴, K Kobayashi^{3

4}, K Kohri²⁶, H S Krawczynski⁹, J F Krizmanic¹², P Maestro^{7

8}, P S Marrocchesi^{7

8}, A M Messineo^{8

27}, J W Mitchell¹², S Miyake²⁸, A A Moiseev^{12

13

29}, M Mori³⁰, N Mori², H M Motz¹⁸, K Munakata²⁵, S Nakahira¹⁷, J Nishimura¹⁷, S Okuno¹⁸, J F Ormes³¹, S Ozawa³², L Pacini^{2

6}, P Papini², B F Rauch⁹, S B Ricciarini^{2

6}, K Sakai^{11

12

13}, T Sakamoto³³, M Sasaki^{12

13

29}, Y Shimizu¹⁸, A Shiomi³⁴, P Spillantini¹, F Stolzi^{7

8}, S Sugita³³, A Sulaj^{7

8}, M Takita⁵, T Tamura¹⁸, T Terasawa⁵, S Torii³, Y Tsunesada^{35

36}, Y Uchihori³⁷, E Vannuccini², J P Wefel¹⁴, K Yamaoka³⁸, S Yanagita³⁹, A Yoshida³³, K Yoshida²¹, W V Zober⁹; CALET Collaboration

Affiliations

¹ Department of Physics, University of Florence, Via Sansone, 1-50019, Sesto Fiorentino, Italy.
² INFN Sezione di Florence, Via Sansone, 1-50019, Sesto Fiorentino, Italy.
³ Waseda Research Institute for Science and Engineering, Waseda University, 17 Kikuicho, Shinjuku, Tokyo 162-0044, Japan.
⁴ JEM Utilization Center, Human Spaceflight Technology Directorate, Japan Aerospace Exploration Agency, 2-1-1 Sengen, Tsukuba, Ibaraki 305-8505, Japan.
⁵ Institute for Cosmic Ray Research, The University of Tokyo, 5-1-5 Kashiwa-no-Ha, Kashiwa, Chiba 277-8582, Japan.
⁶ Institute of Applied Physics (IFAC), National Research Council (CNR), Via Madonna del Piano, 10, 50019, Sesto Fiorentino, Italy.
⁷ Department of Physical Sciences, Earth and Environment, University of Siena, via Roma 56, 53100 Siena, Italy.
⁸ INFN Sezione di Pisa, Polo Fibonacci, Largo B. Pontecorvo, 3-56127 Pisa, Italy.
⁹ Department of Physics and McDonnell Center for the Space Sciences, Washington University, One Brookings Drive, St. Louis, Missouri 63130-4899, USA.
¹⁰ Heliospheric Physics Laboratory, NASA/GSFC, Greenbelt, Maryland 20771, USA.
¹¹ Center for Space Sciences and Technology, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, Maryland 21250, USA.
¹² Astroparticle Physics Laboratory, NASA/GSFC, Greenbelt, Maryland 20771, USA.
¹³ Center for Research and Exploration in Space Sciences and Technology, NASA/GSFC, Greenbelt, Maryland 20771, USA.
¹⁴ Department of Physics and Astronomy, Louisiana State University, 202 Nicholson Hall, Baton Rouge, Louisiana 70803, USA.
¹⁵ Department of Physics and Astronomy, University of Padova, Via Marzolo, 8, 35131 Padova, Italy.
¹⁶ INFN Sezione di Padova, Via Marzolo, 8, 35131 Padova, Italy.
¹⁷ Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo, Sagamihara, Kanagawa 252-5210, Japan.
¹⁸ Kanagawa University, 3-27-1 Rokkakubashi, Kanagawa, Yokohama, Kanagawa 221-8686, Japan.
¹⁹ Faculty of Science and Technology, Graduate School of Science and Technology, Hirosaki University, 3, Bunkyo, Hirosaki, Aomori 036-8561, Japan.
²⁰ Yukawa Institute for Theoretical Physics, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan.
²¹ Department of Electronic Information Systems, Shibaura Institute of Technology, 307 Fukasaku, Minuma, Saitama 337-8570, Japan.
²² School of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan.
²³ National Institute of Polar Research, 10-3, Midori-cho, Tachikawa, Tokyo 190-8518, Japan.
²⁴ Faculty of Engineering, Division of Intelligent Systems Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya, Yokohama 240-8501, Japan.
²⁵ Faculty of Science, Shinshu University, 3-1-1 Asahi, Matsumoto, Nagano 390-8621, Japan.
²⁶ Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki, 305-0801, Japan.
²⁷ University of Pisa, Polo Fibonacci, Largo B. Pontecorvo, 3-56127 Pisa, Italy.
²⁸ Department of Electrical and Electronic Systems Engineering, National Institute of Technology (KOSEN), Ibaraki College, 866 Nakane, Hitachinaka, Ibaraki 312-8508, Japan.
²⁹ Department of Astronomy, University of Maryland, College Park, Maryland 20742, USA.
³⁰ Department of Physical Sciences, College of Science and Engineering, Ritsumeikan University, Shiga 525-8577, Japan.
³¹ Department of Physics and Astronomy, University of Denver, Physics Building, Room 211, 2112 East Wesley Avenue, Denver, Colorado 80208-6900, USA.
³² Quantum ICT Advanced Development Center, National Institute of Information and Communications Technology, 4-2-1 Nukui-Kitamachi, Koganei, Tokyo 184-8795, Japan.
³³ College of Science and Engineering, Department of Physics and Mathematics, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo, Sagamihara, Kanagawa 252-5258, Japan.
³⁴ College of Industrial Technology, Nihon University, 1-2-1 Izumi, Narashino, Chiba 275-8575, Japan.
³⁵ Graduate School of Science, Osaka Metropolitan University, Sugimoto, Sumiyoshi, Osaka 558-8585, Japan.
³⁶ Nambu Yoichiro Institute for Theoretical and Experimental Physics, Osaka Metropolitan University, Sugimoto, Sumiyoshi, Osaka 558-8585, Japan.
³⁷ National Institutes for Quantum and Radiation Science and Technology, 4-9-1 Anagawa, Inage, Chiba 263-8555, Japan.
³⁸ Nagoya University, Furo, Chikusa, Nagoya 464-8601, Japan.
³⁹ College of Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512, Japan.

PMID: 38000434
DOI: 10.1103/PhysRevLett.131.191001

Direct Measurement of the Spectral Structure of Cosmic-Ray Electrons+Positrons in the TeV Region with CALET on the International Space Station

O Adriani et al. Phys Rev Lett. 2023.

. 2023 Nov 10;131(19):191001.

doi: 10.1103/PhysRevLett.131.191001.

Authors

Affiliations

¹ Department of Physics, University of Florence, Via Sansone, 1-50019, Sesto Fiorentino, Italy.
² INFN Sezione di Florence, Via Sansone, 1-50019, Sesto Fiorentino, Italy.
³ Waseda Research Institute for Science and Engineering, Waseda University, 17 Kikuicho, Shinjuku, Tokyo 162-0044, Japan.
⁴ JEM Utilization Center, Human Spaceflight Technology Directorate, Japan Aerospace Exploration Agency, 2-1-1 Sengen, Tsukuba, Ibaraki 305-8505, Japan.
⁵ Institute for Cosmic Ray Research, The University of Tokyo, 5-1-5 Kashiwa-no-Ha, Kashiwa, Chiba 277-8582, Japan.
⁶ Institute of Applied Physics (IFAC), National Research Council (CNR), Via Madonna del Piano, 10, 50019, Sesto Fiorentino, Italy.
⁷ Department of Physical Sciences, Earth and Environment, University of Siena, via Roma 56, 53100 Siena, Italy.
⁸ INFN Sezione di Pisa, Polo Fibonacci, Largo B. Pontecorvo, 3-56127 Pisa, Italy.
⁹ Department of Physics and McDonnell Center for the Space Sciences, Washington University, One Brookings Drive, St. Louis, Missouri 63130-4899, USA.
¹⁰ Heliospheric Physics Laboratory, NASA/GSFC, Greenbelt, Maryland 20771, USA.
¹¹ Center for Space Sciences and Technology, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, Maryland 21250, USA.
¹² Astroparticle Physics Laboratory, NASA/GSFC, Greenbelt, Maryland 20771, USA.
¹³ Center for Research and Exploration in Space Sciences and Technology, NASA/GSFC, Greenbelt, Maryland 20771, USA.
¹⁴ Department of Physics and Astronomy, Louisiana State University, 202 Nicholson Hall, Baton Rouge, Louisiana 70803, USA.
¹⁵ Department of Physics and Astronomy, University of Padova, Via Marzolo, 8, 35131 Padova, Italy.
¹⁶ INFN Sezione di Padova, Via Marzolo, 8, 35131 Padova, Italy.
¹⁷ Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo, Sagamihara, Kanagawa 252-5210, Japan.
¹⁸ Kanagawa University, 3-27-1 Rokkakubashi, Kanagawa, Yokohama, Kanagawa 221-8686, Japan.
¹⁹ Faculty of Science and Technology, Graduate School of Science and Technology, Hirosaki University, 3, Bunkyo, Hirosaki, Aomori 036-8561, Japan.
²⁰ Yukawa Institute for Theoretical Physics, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan.
²¹ Department of Electronic Information Systems, Shibaura Institute of Technology, 307 Fukasaku, Minuma, Saitama 337-8570, Japan.
²² School of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan.
²³ National Institute of Polar Research, 10-3, Midori-cho, Tachikawa, Tokyo 190-8518, Japan.
²⁴ Faculty of Engineering, Division of Intelligent Systems Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya, Yokohama 240-8501, Japan.
²⁵ Faculty of Science, Shinshu University, 3-1-1 Asahi, Matsumoto, Nagano 390-8621, Japan.
²⁶ Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki, 305-0801, Japan.
²⁷ University of Pisa, Polo Fibonacci, Largo B. Pontecorvo, 3-56127 Pisa, Italy.
²⁸ Department of Electrical and Electronic Systems Engineering, National Institute of Technology (KOSEN), Ibaraki College, 866 Nakane, Hitachinaka, Ibaraki 312-8508, Japan.
²⁹ Department of Astronomy, University of Maryland, College Park, Maryland 20742, USA.
³⁰ Department of Physical Sciences, College of Science and Engineering, Ritsumeikan University, Shiga 525-8577, Japan.
³¹ Department of Physics and Astronomy, University of Denver, Physics Building, Room 211, 2112 East Wesley Avenue, Denver, Colorado 80208-6900, USA.
³² Quantum ICT Advanced Development Center, National Institute of Information and Communications Technology, 4-2-1 Nukui-Kitamachi, Koganei, Tokyo 184-8795, Japan.
³³ College of Science and Engineering, Department of Physics and Mathematics, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo, Sagamihara, Kanagawa 252-5258, Japan.
³⁴ College of Industrial Technology, Nihon University, 1-2-1 Izumi, Narashino, Chiba 275-8575, Japan.
³⁵ Graduate School of Science, Osaka Metropolitan University, Sugimoto, Sumiyoshi, Osaka 558-8585, Japan.
³⁶ Nambu Yoichiro Institute for Theoretical and Experimental Physics, Osaka Metropolitan University, Sugimoto, Sumiyoshi, Osaka 558-8585, Japan.
³⁷ National Institutes for Quantum and Radiation Science and Technology, 4-9-1 Anagawa, Inage, Chiba 263-8555, Japan.
³⁸ Nagoya University, Furo, Chikusa, Nagoya 464-8601, Japan.
³⁹ College of Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512, Japan.

PMID: 38000434
DOI: 10.1103/PhysRevLett.131.191001

Abstract

Detailed measurements of the spectral structure of cosmic-ray electrons and positrons from 10.6 GeV to 7.5 TeV are presented from over 7 years of observations with the CALorimetric Electron Telescope (CALET) on the International Space Station. The instrument, consisting of a charge detector, an imaging calorimeter, and a total absorption calorimeter with a total depth of 30 radiation lengths at normal incidence and a fine shower imaging capability, is optimized to measure the all-electron spectrum well into the TeV region. Because of the excellent energy resolution (a few percent above 10 GeV) and the outstanding e/p separation (10^{5}), CALET provides optimal performance for a detailed search of structures in the energy spectrum. The analysis uses data up to the end of 2022, and the statistics of observed electron candidates has increased more than 3 times since the last publication in 2018. By adopting an updated boosted decision tree analysis, a sufficient proton rejection power up to 7.5 TeV is achieved, with a residual proton contamination less than 10%. The observed energy spectrum becomes gradually harder in the lower energy region from around 30 GeV, consistently with AMS-02, but from 300 to 600 GeV it is considerably softer than the spectra measured by DAMPE and Fermi-LAT. At high energies, the spectrum presents a sharp break around 1 TeV, with a spectral index change from -3.15 to -3.91, and a broken power law fitting the data in the energy range from 30 GeV to 4.8 TeV better than a single power law with 6.9 sigma significance, which is compatible with the DAMPE results. The break is consistent with the expected effects of radiation loss during the propagation from distant sources (except the highest energy bin). We have fitted the spectrum with a model consistent with the positron flux measured by AMS-02 below 1 TeV and interpreted the electron+positron spectrum with possible contributions from pulsars and nearby sources. Above 4.8 TeV, a possible contribution from known nearby supernova remnants, including Vela, is addressed by an event-by-event analysis providing a higher proton-rejection power than a purely statistical analysis.

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Direct Measurement of the Spectral Structure of Cosmic-Ray Electrons+Positrons in the TeV Region with CALET on the International Space Station

Affiliations

Direct Measurement of the Spectral Structure of Cosmic-Ray Electrons+Positrons in the TeV Region with CALET on the International Space Station

Authors

Affiliations

Abstract

LinkOut - more resources

Full Text Sources

Research Materials