Charge–Sign Dependent Drift Effects in the Time–Lag of Cosmic–Ray Variation Relative to Solar Activity Observed with the Calorimetric Electron Telescope (CALET)

Abstract The 11-yr variation of galactic cosmic-ray flux lags behind the variation of the sunspot number. An average $\sim$1-yr time-lag is expected from the outward propagating solar wind with the frozen-in photospheric magnetic field varying in the solar cycle, and from the inward diffusive transport of cosmic-ray particles. The long-term neutron monitor data, however, show that the time-lag is significantly longer (shorter) in the odd (even) solar cycle. In this paper, we analyze the time-lag in proton and electron fluxes observed by the Calorimetric Electron Telescope (CALET). It is found that the time-lag is similar in proton and electron fluxes during an $A > 0$ polarity epoch of the solar dipole magnetic field. In an even solar cycle 24 including a polarity reversal from $A < 0$ to $A > 0$, on the other hand, it is found that the time-lag of proton (electron) flux variation is significantly shorter (longer) than the average $\sim$1-yr lag by analyzing the combined data with CALET and AMS-02. This is the first observation of the charge-sign dependent time-lag. We demonstrate that these observations can be qualitatively interpreted in terms of different 11-yr time profiles of proton and electron fluxes in $A > 0$ and $A < 0$ epochs expected from the drift effect.

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Publication Details

Journal
Progress of Theoretical and Experimental Physics
Published
2026-02-17
DOI
https://doi.org/10.1093/ptep/ptag025
Primary Topic
Solar and Space Plasma Dynamics
Type
article
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article

Charge–Sign Dependent Drift Effects in the Time–Lag of Cosmic–Ray Variation Relative to Solar Activity Observed with the Calorimetric Electron Telescope (CALET)

Ken Ebisawa, Giovanni Castellini, Y. Katayose, S. Yanagita et al.
Progress of Theoretical and Experimental Physics
Solar and Space Plasma Dynamics
article

Charge–Sign Dependent Drift Effects in the Time–Lag of Cosmic–Ray Variation Relative to Solar Activity Observed with the Calorimetric Electron Telescope (CALET)

Ken Ebisawa, Giovanni Castellini, Y. Katayose, S. Yanagita, Jun Kataoka, T. Sakamoto, Shoko Miyake, P. Betti, Adrien Picquenot, Pedro Augusto Papini, Y. Kawakubo, K. Asano, C. Kato, J F Ormes, J P Wefel, S Torii, M H Israel, A Yoshida, S Ozawa, N Cannady, L W Blum, W V Zober, J F Krizmanic, S Okuno, J W Mitchell, K Kobayashi, L Pacini, M Takita, G A de Nolfo, R Kataoka, N Mori, S Sugita, O Adriani, K Yamaoka, K Yoshida, A Bruno, G Bigongiari, W R Binns, K Munakata, M Ichimura, H Fuke, A Shiomi, M Mattiazzi, K Hibino, H M Motz, K Kasahara, E Berti, E Vannuccini, T Tamura, K Kohri, P Brogi, M Mori, Y Kato, N Kawanaka, T Terasawa, P S Marrocchesi, K Sakai, S B Ricciarini, H S Krawczynski, Y Asaoka, Y Akaike, T G Guzik, A W Ficklin, M L Cherry, M Teramoto, P Maestro, T Hams, C Checchia, S Gonzi, B F Rauch, A A Moiseev, A M Messineo, M Bongi, Y Shimizu, P Spillantini
article en

Abstract

Abstract The 11-yr variation of galactic cosmic-ray flux lags behind the variation of the sunspot number. An average $\sim$1-yr time-lag is expected from the outward propagating solar wind with the frozen-in photospheric magnetic field varying in the solar cycle, and from the inward diffusive transport of cosmic-ray particles. The long-term neutron monitor data, however, show that the time-lag is significantly longer (shorter) in the odd (even) solar cycle. In this paper, we analyze the time-lag in proton and electron fluxes observed by the Calorimetric Electron Telescope (CALET). It is found that the time-lag is similar in proton and electron fluxes during an $A > 0$ polarity epoch of the solar dipole magnetic field. In an even solar cycle 24 including a polarity reversal from $A < 0$ to $A > 0$, on the other hand, it is found that the time-lag of proton (electron) flux variation is significantly shorter (longer) than the average $\sim$1-yr lag by analyzing the combined data with CALET and AMS-02. This is the first observation of the charge-sign dependent time-lag. We demonstrate that these observations can be qualitatively interpreted in terms of different 11-yr time profiles of proton and electron fluxes in $A > 0$ and $A < 0$ epochs expected from the drift effect.

Progress of Theoretical and Experimental PhysicsVol. 2026(3)
University of Siena (IT), Brookings Institution (US), Louisiana State University (US), Goddard Space Flight Center (US), Aoyama Gakuin University (JP), University of Denver (US), Ritsumeikan University (JP), Shinshu University (JP), University of Padua (IT), High Energy Accelerator Research Organization (JP), Okinawa Institute of Science and Technology Graduate University (JP), Hirosaki University (JP), Waseda University (JP), University of America (US), Shibaura Institute of Technology (JP), Yokohama National University (JP), Tohoku University (JP), Kyushu Institute of Technology (JP), Japan Aerospace Exploration Agency (JP), Osaka City University (JP), University of Chicago (US), Kanagawa University (JP), Istituto Nazionale di Fisica Nucleare, Sezione di Padova (IT), National Institute of Technology, Gifu College (JP), Laboratory for Atmospheric and Space Physics (US), National Institutes for Quantum Science and Technology (JP), Kavli Institute for the Physics and Mathematics of the Universe (JP), Shinshu University Hospital (JP), Istituto Nazionale di Fisica Nucleare, Sezione di Firenze (IT), Istituto per la Valorizzazione del Legno e delle Specie Arboree (IT), Osservatorio Astronomico di Padova (IT), National Astronomical Observatory of Japan (JP), Istituto Nazionale di Fisica Nucleare, Sezione di Pisa (IT), University of Florence (IT), College of Industrial Technology (JP), Nagoya University (JP), Ibaraki University (JP), University of Maryland, College Park (US), Tokyo Metropolitan University (JP), University of Maryland, Baltimore County (US), Catholic University of America (US), National Institute of Information and Communications Technology (JP)
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