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1. First High‐Speed Video Camera Observations of a Lightning Flash Associated With a Downward Terrestrial Gamma‐Ray Flash

Author: R. U. Abbasi, M. M. F. Saba, J. W. Belz, P. R. Krehbiel, W. Rison, N. Kieu, D. R. daSilva, M. A. Stanley, Dan Rodeheffer, J. Remington, J. Mazich, R. LeVon, K. Smout, A. Petrizze, T. Abu‐Zayyad, M. Allen, R. Arimura, E. Barcikowski, D. R. Bergman, S. A. Blake, I. Buckland, B. G. Cheon, M. Chikawa, T. Fujii, K. Fujisue, K. Fujita, R. Fujiwara, M. Fukushima, G. Furlich, N. Globus, R. Gonzalez, W. Hanlon, N. Hayashida, H. He, K. Hibino, R. Higuchi, K. Honda, D. Ikeda, N. Inoue, T. Ishii, H. Ito, D. Ivanov, H. Iwakura, A. Iwasaki, H. M. Jeong, S. Jeong, C. C. H. Jui, K. Kadota, F. Kakimoto, O. Kalashev, K. Kasahara, S. Kasami, S. Kawakami, K. Kawata, I. Kharuk, E. Kido, H. B. Kim, J. H. Kim, S. W. Kim, Y. Kimura, I. Komae, Y. Kubota, M. Kuznetsov, Y. J. Kwon, K. H. Lee, B. Lubsandorzhiev, J. P. Lundquist, T. Matsuyama, J. N. Matthews, R. Mayta, I. Myers, S. Nagataki, K. Nakai, R. Nakamura, T. Nakamura, A. Nakazawa, E. Nishio, T. Nonaka, S. Ogio, M. Ohnishi, H. Ohoka, Y. Oku, T. Okuda, Y. Omura, M. Ono, A. Oshima, S. Ozawa, I. H. Park, M. Potts, M. S. Pshirkov, D. C. Rodriguez, C. Rott, G. I. Rubtsov, D. Ryu, H. Sagawa, N. Sakaki, T. Sako, N. Sakurai, K. Sato, T. Seki, K. Sekino, P. D. Shah, Y. Shibasaki, N. Shibata, T. Shibata, J. Shikita, H. Shimodaira, B. K. Shin, H. S. Shin, D. Shinto, J. D. Smith, P. Sokolsky, B. T. Stokes, T. A. Stroman, K. Takahashi, M. Takamura, M. Takeda, R. Takeishi, A. Taketa, M. Takita, Y. Tameda, K. Tanaka, M. Tanaka, S. B. Thomas, G. B. Thomson, P. Tinyakov, I. Tkachev, H. Tokuno, T. Tomida, S. Troitsky, R. Tsuda, Y. Tsunesada, S. Udo, T. Uehama, F. Urban, D. Warren, T. Wong, M. Yamamoto, K. Yamazaki, K. Yashiro, F. Yoshida, Y. Zhezher, and Z. Zundel
Subjects: lightning, terrestrial gamma‐ray flashes, cosmic ray detectors, Geophysics. Cosmic physics, QC801-809
Abstract: Abstract In this paper, we present the first high‐speed video observation of a cloud‐to‐ground lightning flash and its associated downward‐directed Terrestrial Gamma‐ray Flash (TGF). The optical emission of the event was observed by a high‐speed video camera running at 40,000 frames per second in conjunction with the Telescope Array Surface Detector, Lightning Mapping Array, interferometer, electric‐field fast antenna, and the National Lightning Detection Network. The cloud‐to‐ground flash associated with the observed TGF was formed by a fast downward leader followed by a very intense return stroke peak current of −154 kA. The TGF occurred while the downward leader was below cloud base, and even when it was halfway in its propagation to ground. The suite of gamma‐ray and lightning instruments, timing resolution, and source proximity offer us detailed information and therefore a unique look at the TGF phenomena.
Published: 2023
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2. Observation of Gamma Rays up to 320 TeV from the Middle-aged TeV Pulsar Wind Nebula HESS J1849−000

Author: M. Amenomori, S. Asano, Y. W. Bao, X. J. Bi, D. Chen, T. L. Chen, W. Y. Chen, Xu Chen, Y. Chen, Cirennima, S. W. Cui, Danzengluobu, L. K. Ding, J. H. Fang, K. Fang, C. F. Feng, Zhaoyang Feng, Z. Y. Feng, Qi Gao, A. Gomi, Q. B. Gou, Y. Q. Guo, Y. Y. Guo, Y. Hayashi, H. H. He, Z. T. He, K. Hibino, N. Hotta, Haibing Hu, H. B. Hu, K. Y. Hu, J. Huang, H. Y. Jia, L. Jiang, P. Jiang, H. B. Jin, K. Kasahara, Y. Katayose, C. Kato, S. Kato, I. Kawahara, T. Kawashima, K. Kawata, M. Kozai, D. Kurashige, Labaciren, G. M. Le, A. F. Li, H. J. Li, W. J. Li, Y. Li, Y. H. Lin, B. Liu, C. Liu, J. S. Liu, L. Y. Liu, M. Y. Liu, W. Liu, H. Lu, X. R. Meng, Y. Meng, K. Munakata, K. Nagaya, Y. Nakamura, Y. Nakazawa, H. Nanjo, C. C. Ning, M. Nishizawa, R. Noguchi, M. Ohnishi, S. Okukawa, S. Ozawa, X. Qian, X. L. Qian, X. B. Qu, T. Saito, Y. Sakakibara, M. Sakata, T. Sako, T. K. Sako, T. Sasaki, J. Shao, M. Shibata, A. Shiomi, H. Sugimoto, W. Takano, M. Takita, Y. H. Tan, N. Tateyama, S. Torii, H. Tsuchiya, S. Udo, H. Wang, S. F. Wang, Y. P. Wang, Wangdui, H. R. Wu, Q. Wu, J. L. Xu, L. Xue, Z. Yang, Y. Q. Yao, J. Yin, Y. Yokoe, Y. L. Yu, A. F. Yuan, L. M. Zhai, H. M. Zhang, J. L. Zhang, X. Zhang, X. Y. Zhang, Y. Zhang, Yi Zhang, Ying Zhang, S. P. Zhao, Zhaxisangzhu, X. X. Zhou, and Y. H. Zou
Subjects: Galactic cosmic rays, Pulsar wind nebulae, Gamma-ray sources, Gamma-ray astronomy, Gamma-ray observatories, Astrophysics, QB460-466
Abstract: Gamma rays from HESS J1849−000, a middle-aged TeV pulsar wind nebula (PWN), are observed by the Tibet air shower array and the muon detector array. The detection significance of gamma rays reaches 4.0 σ and 4.4 σ levels above 25 TeV and 100 TeV, respectively, in units of the Gaussian standard deviation σ . The energy spectrum measured between 40 TeV < E < 320 TeV for the first time is described with a simple power-law function of ${dN}/{dE}={(2.86\pm 1.44)\times {10}^{-16}(E/40\,\mathrm{TeV})}^{-2.24\pm 0.41}\,{\mathrm{TeV}}^{-1}\,{\mathrm{cm}}^{-2}\,{{\rm{s}}}^{-1}$ . The gamma-ray energy spectrum from the sub-TeV ( E < 1 TeV) to sub-PeV (100 TeV < E < 1 PeV) ranges, including the results of previous studies, can be modeled with the leptonic scenario, i.e., inverse Compton scattering by high-energy electrons accelerated by the PWN of PSR J1849−0001. On the other hand, the gamma-ray energy spectrum can also be modeled with the hadronic scenario in which gamma rays are generated from the decay of neutral pions produced by collisions between accelerated cosmic-ray protons and the ambient molecular cloud found in the gamma-ray-emitting region. The cutoff energy of cosmic-ray protons E _p,cut is estimated as ${\mathrm{log}}_{10}({E}_{{\rm{p}},\mathrm{cut}}/\mathrm{TeV})={3.73}_{-0.66}^{+2.98}$ , suggesting that protons are accelerated up to the PeV energy range. Our study thus proposes that HESS J1849−000 should be further investigated as a new candidate as a Galactic PeV cosmic-ray accelerator, or “PeVatron.”
Published: 2023
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3. Energetics and structure of the lower E region associated with sporadic E layer

Author: K.-I. Oyama, K. Hibino, T. Abe, R. Pfaff, T. Yokoyama, and J. Y. Liu
Subjects: Science, Physics, QC1-999, Geophysics. Cosmic physics, QC801-809
Abstract: The electron temperature (Te), electron density (Ne), and two components of the electric field were measured from the height of 90 km to 150 km by one of the sounding rockets launched during the SEEK-2 campaign. The rocket went through sporadic E layer (Es) at the height of 102 km–109 km during ascent and 99 km–108 km during decent, respectively. The energy density of thermal electrons calculated from Ne and Te shows the broad maximum in the height range of 100–110 km, and it decreases towards the lower and higher altitudes, which implies that a heat source exists in the height region of 100 km–110 km. A 3-D picture of Es, that was drawn by using Te, Ne, and the electric field data, corresponded to the computer simulation; the main structure of Es is projected to a higher altitude along the magnetic line of force, thus producing irregular structures of Te, Ne and electric field in higher altitude.
Published: 2008
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4. Direct Measurement of the Spectral Structure of Cosmic-Ray Electrons+Positrons in the TeV Region with CALET on the International Space Station

Author: O. Adriani, Y. Akaike, K. Asano, Y. Asaoka, E. Berti, G. Bigongiari, W. R. Binns, M. Bongi, P. Brogi, A. Bruno, J. H. Buckley, N. Cannady, G. Castellini, C. Checchia, M. L. Cherry, G. Collazuol, G. A. de Nolfo, K. Ebisawa, A. W. Ficklin, H. Fuke, S. Gonzi, T. G. Guzik, T. Hams, K. Hibino, M. Ichimura, K. Ioka, W. Ishizaki, M. H. Israel, K. Kasahara, J. Kataoka, R. Kataoka, Y. Katayose, C. Kato, N. Kawanaka, Y. Kawakubo, K. Kobayashi, K. Kohri, H. S. Krawczynski, J. F. Krizmanic, P. Maestro, P. S. Marrocchesi, A. M. Messineo, J. W. Mitchell, S. Miyake, A. A. Moiseev, M. Mori, N. Mori, H. M. Motz, K. Munakata, S. Nakahira, J. Nishimura, S. Okuno, J. F. Ormes, S. Ozawa, L. Pacini, P. Papini, B. F. Rauch, S. B. Ricciarini, K. Sakai, T. Sakamoto, M. Sasaki, Y. Shimizu, A. Shiomi, P. Spillantini, F. Stolzi, S. Sugita, A. Sulaj, M. Takita, T. Tamura, T. Terasawa, S. Torii, Y. Tsunesada, Y. Uchihori, E. Vannuccini, J. P. Wefel, K. Yamaoka, S. Yanagita, A. Yoshida, K. Yoshida, and W. V. Zober
Published: 2023
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5. Charge-Sign Dependent Cosmic-Ray Modulation Observed with the Calorimetric Electron Telescope on the International Space Station

Author: O. Adriani, Y. Akaike, K. Asano, Y. Asaoka, E. Berti, G. Bigongiari, W.R. Binns, M. Bongi, P. Brogi, A. Bruno, J.H. Buckley, N. Cannady, G. Castellini, C. Checchia, M.L. Cherry, G. Collazuol, G.A. de Nolfo, K. Ebisawa, A. W. Ficklin, H. Fuke, S. Gonzi, T.G. Guzik, T. Hams, K. Hibino, M. Ichimura, K. Ioka, W. Ishizaki, M.H. Israel, K. Kasahara, J. Kataoka, R. Kataoka, Y. Katayose, C. Kato, N. Kawanaka, Y. Kawakubo, K. Kobayashi, K. Kohri, H.S. Krawczynski, J.F. Krizmanic, P. Maestro, P.S. Marrocchesi, A.M. Messineo, J.W. Mitchell, S. Miyake, A.A. Moiseev, M. Mori, N. Mori, H.M. Motz, K. Sakai, and M. Sasaki
Subjects: Space Sciences (General), Instrumentation and Photography
Abstract: We present the observation of a charge-sign dependent solar modulation of galactic cosmic rays (GCRs) with the Calorimetric Electron Telescope onboard the International Space Station over 6 yr, corresponding to the positive polarity of the solar magnetic field. The observed variation of proton count rate is consistent with the neutron monitor count rate, validating our methods for determining the proton count rate. It is observed by the Calorimetric Electron Telescope that both GCR electron and proton count rates at the same average rigidity vary in anticorrelation with the tilt angle of the heliospheric current sheet, while the amplitude of the variation is significantly larger in the electron count rate than in the proton count rate. We show that this observed charge-sign dependence is reproduced by a numerical “drift model” of the GCR transport in the heliosphere. This is a clear signature of the drift effect on the long-term solar modulation observed with a single detector.
Published: 2023
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6. Direct Measurement of the Cosmic-Ray Helium Spectrum from 40 GeV to 250 TeV with the Calorimetric Electron Telescope on the International Space Station

Author: O. Adriani, Y. Akaike, K. Asano, Y. Asaoka, E. Berti, G. Bigongiari, W. R. Binns, M. Bongi, P. Brogi, A. Bruno, J. H. Buckley, N. Cannady, G. Castellini, C. Checchia, M. L. Cherry, G. Collazuol, G. A. de Nolfo, K. Ebisawa, A. W. Ficklin, H. Fuke, S. Gonzi, T. G. Guzik, T. Hams, K. Hibino, M. Ichimura, K. Ioka, W. Ishizaki, M. H. Israel, K. Kasahara, J. Kataoka, R. Kataoka, Y. Katayose, C. Kato, N. Kawanaka, Y. Kawakubo, K. Kobayashi, K. Kohri, H. S. Krawczynski, J. F. Krizmanic, P. Maestro, P. S. Marrocchesi, A. M. Messineo, J. W. Mitchell, S. Miyake, A. A. Moiseev, M. Mori, N. Mori, H. M. Motz, K. Munakata, S. Nakahira, J. Nishimura, S. Okuno, J. F. Ormes, S. Ozawa, L. Pacini, P. Papini, B. F. Rauch, S. B. Ricciarini, K. Sakai, T. Sakamoto, M. Sasaki, Y. Shimizu, A. Shiomi, P. Spillantini, F. Stolzi, S. Sugita, A. Sulaj, M. Takita, T. Tamura, T. Terasawa, S. Torii, Y. Tsunesada, Y. Uchihori, E. Vannuccini, J. P. Wefel, K. Yamaoka, S. Yanagita, A. Yoshida, K. Yoshida, and W. V. Zober
Published: 2023
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7. Cosmic-Ray Boron Flux Measured from 8.4 GeV/n to 3.8 TeV/n with the Calorimetric Electron Telescope on the International Space Station

Author: O. Adriani, Y. Akaike, K. Asano, Y. Asaoka, E. Berti, G. Bigongiari, W. R. Binns, M. Bongi, P. Brogi, A. Bruno, J. H. Buckley, N. Cannady, G. Castellini, C. Checchia, M. L. Cherry, G. Collazuol, G. A. de Nolfo, K. Ebisawa, A. W. Ficklin, H. Fuke, S. Gonzi, T. G. Guzik, T. Hams, K. Hibino, M. Ichimura, K. Ioka, W. Ishizaki, M. H. Israel, K. Kasahara, J. Kataoka, R. Kataoka, Y. Katayose, C. Kato, N. Kawanaka, Y. Kawakubo, K. Kobayashi, K. Kohri, H. S. Krawczynski, J. F. Krizmanic, P. Maestro, P. S. Marrocchesi, A. M. Messineo, J. W. Mitchell, S. Miyake, A. A. Moiseev, M. Mori, N. Mori, H. M. Motz, K. Munakata, S. Nakahira, J. Nishimura, S. Okuno, J. F. Ormes, S. Ozawa, L. Pacini, P. Papini, B. F. Rauch, S. B. Ricciarini, K. Sakai, T. Sakamoto, M. Sasaki, Y. Shimizu, A. Shiomi, P. Spillantini, F. Stolzi, S. Sugita, A. Sulaj, M. Takita, T. Tamura, T. Terasawa, S. Torii, Y. Tsunesada, Y. Uchihori, E. Vannuccini, J. P. Wefel, K. Yamaoka, S. Yanagita, A. Yoshida, K. Yoshida, and W. V. Zober
Published: 2022
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8. Observation of Spectral Structures in the Flux of Cosmic-Ray Protons from 50 GeV to 60 TeV with the Calorimetric Electron Telescope on the International Space Station

Author: O. Adriani, Y. Akaike, K. Asano, Y. Asaoka, E. Berti, G. Bigongiari, W. R. Binns, M. Bongi, P. Brogi, A. Bruno, J. H. Buckley, N. Cannady, G. Castellini, C. Checchia, M. L. Cherry, G. Collazuol, K. Ebisawa, A. W. Ficklin, H. Fuke, S. Gonzi, T. G. Guzik, T. Hams, K. Hibino, M. Ichimura, K. Ioka, W. Ishizaki, M. H. Israel, K. Kasahara, J. Kataoka, R. Kataoka, Y. Katayose, C. Kato, N. Kawanaka, Y. Kawakubo, K. Kobayashi, K. Kohri, H. S. Krawczynski, J. F. Krizmanic, P. Maestro, P. S. Marrocchesi, A. M. Messineo, J. W. Mitchell, S. Miyake, A. A. Moiseev, M. Mori, N. Mori, H. M. Motz, K. Munakata, S. Nakahira, J. Nishimura, G. A. de Nolfo, S. Okuno, J. F. Ormes, S. Ozawa, L. Pacini, P. Papini, B. F. Rauch, S. B. Ricciarini, K. Sakai, T. Sakamoto, M. Sasaki, Y. Shimizu, A. Shiomi, P. Spillantini, F. Stolzi, S. Sugita, A. Sulaj, M. Takita, T. Tamura, T. Terasawa, S. Torii, Y. Tsunesada, Y. Uchihori, E. Vannuccini, J. P. Wefel, K. Yamaoka, S. Yanagita, A. Yoshida, K. Yoshida, and W. V. Zober
Published: 2022
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9. CALET Search for Electromagnetic Counterparts of Gravitational Waves During the LIGO/Virgo O3 Run

Author: O Adriani, Y Akaike, K Asano, Y Asaoka, E Berti, G Bigongiari, W R Binns, M Bongi, P Brogi, A Bruno, J H Buckley, N Cannady, G Castellini, C Checchia, M L Cherry, G Collazuol, K Ebisawa, A W Ficklin, H Fuke, S Gonzi, T G Guzik, T Hams, K Hibino, M Ichimura, K Ioka, W Ishizak, M H Israel, K Kasahara, J Kataoka, R Kataoka, Y Katayose, C Kato, N Kawanaka, Y Kawakubo, K Kobayashi, K Kohri, H S Krawczynski, J F Krizmanic, P Maestro, P S Marrocches, A M Messineo, J W Mitchell, S Miyake, A A Moiseev, M Mori, N Mori, H M Motz, K Munakata, S Nakahira, J Nishimura, G A de Nolfo, S Okuno, J F Ormes, N Ospina, S Ozawa, L Pacini, P Papini, B F Rauch, S B Ricciarini, K Sakai, T Sakamoto, M Sasaki, Y Shimizu, A Shiomi, P Spillantini, F Stolzi, S Sugita, A Sulaj, M Takita, T Tamura, T Terasawa, S Torii, Y Tsunesada, Y Uchihori, E Vannuccini, J P Wefel, K Yamaoka, S Yanagita, A Yoshida, K Yoshida, and W V Zober
Subjects: Astronomy
Abstract: The CALorimetric Electron Telescope (CALET)on the International Space Station consists of a high-energy cosmic-ray CALorimeter (CAL)and a lower-energy CALET Gamma-ray Burst Monitor (CGBM). CAL is sensitive to electrons up to 20 TeV, cosmic-ray nuclei from Z=1 throughZ∼40, and gamma rays over the range1 GeV–10 TeV. CGBM observes gamma rays from 7 keV to 20 MeV. The combined CAL-CGBM instrument has conducted a search for gamma-ray bursts (GRBs)since 2015 October. We report here on the results of a search for X-ray/gamma-ray counterparts to gravitational-wave events reported during the LIGO/Virgo observing run O3. No events have been detected that pass all acceptance criteria. We describe the components, performance, and triggering algorithms of the CGBM—the two Hard X-ray Monitors consisting of LaBr3(Ce)scintillators sensitive to 7 keV–1 MeV gamma rays and a Soft Gamma-ray Monitor BGO scintillator sensitive to 40 keV–20 MeV—and the high-energy CAL consisting of a charge detection module, imaging calorimeter, and the fully active total absorption calorimeter. The analysis procedure is described and upper limits to the time-averaged fluxes are presented.
Published: 2022
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10. Direct Measurement of the Nickel Spectrum in Cosmic Rays in the Energy Range from 8.8 GeV/n to 240 GeV/n with CALET on the International Space Station

Author: O. Adriani, Y. Akaike, K. Asano, Y. Asaoka, E. Berti, G. Bigongiari, W. R. Binns, M. Bongi, P. Brogi, A. Bruno, J. H. Buckley, N. Cannady, G. Castellini, C. Checchia, M. L. Cherry, G. Collazuol, K. Ebisawa, A. W. Ficklin, H. Fuke, S. Gonzi, T. G. Guzik, T. Hams, K. Hibino, M. Ichimura, K. Ioka, W. Ishizaki, M. H. Israel, K. Kasahara, J. Kataoka, R. Kataoka, Y. Katayose, C. Kato, N. Kawanaka, Y. Kawakubo, K. Kobayashi, K. Kohri, H. S. Krawczynski, J. F. Krizmanic, P. Maestro, P. S. Marrocchesi, A. M. Messineo, J. W. Mitchell, S. Miyake, A. A. Moiseev, M. Mori, N. Mori, H. M. Motz, K. Munakata, S. Nakahira, J. Nishimura, G. A. de Nolfo, S. Okuno, J. F. Ormes, N. Ospina, S. Ozawa, L. Pacini, P. Papini, B. F. Rauch, S. B. Ricciarini, K. Sakai, T. Sakamoto, M. Sasaki, Y. Shimizu, A. Shiomi, P. Spillantini, F. Stolzi, S. Sugita, A. Sulaj, M. Takita, T. Tamura, T. Terasawa, S. Torii, Y. Tsunesada, Y. Uchihori, E. Vannuccini, J. P. Wefel, K. Yamaoka, S. Yanagita, A. Yoshida, K. Yoshida, and W. V. Zober
Published: 2022
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11. Precision Measurement of the Nickel Spectrum in Cosmic Rays from 8.8 GeV/n to 240 GeV/n with CALET on the International Space Station

Author: O Adriani, Y Akaike, K Asano, Y Asaoka, E Berti, G Bigongiari, W R Binns, M Bongi, P Brogi, A Bruno, J H Buckley, N Cannady, G Castellini, C Checcia, M L Cherry, G Collazuol, K Ebisawa, A W Ficklin, H Fuke, S Gonzi, T G Guzik, T Hams, K Hibino, M Ichimura, K Ioka, W Ishizaki, M H Israel, K Kasahara, J Kataoka, R Kataoka, Y Katayose, C Kato, A Kawanaka, Y Kawakubo, K Kobayashi, K Kohri, H S Krawczynski, J F Krizmanic, P Maestro, P S Marrocchesi, A M Messineo, J W Mitchell, S Miyake, A A Moiseev, M Mori, N Mori, H M Motz, K Munakata, S Nakahira, and Kenichi Sakai
Subjects: Astronomy, Lunar And Planetary Science And Exploration
Abstract: The relative abundance of nickel with respect to iron is by far larger than all other trans-iron elements, therefore it provides a favourable opportunity for a low background measurement of its spectrum. Since nickel, as well as iron, is one of the most stable nuclei, the nickel energy spectrum and its relative abundance with respect to iron provide important information to estimate the abundances at the source and to model the propagation of heavy nuclei. However, only a few direct measurements of cosmic-ray nickel at energy larger than∼3 GeV/n are available at present in the literature and they are affected by strong limitations in both energy reach and statistics. In this paper we present a measurement of the differential energy spectrum of nickel from 8.8 GeV/nto 240 GeV/n, carried out with unprecedented precision by the Calorimetric Electron1 Telescope(CALET) in operation on the International Space Station since 2015. The CALET instrument can identify individual nuclear species via a measurement of their electric charge with a dynamic range extending far beyond iron (up to atomic number Z = 40). The particle’s energy is measured by a homogeneous calorimeter (1.2 proton interaction lengths, 27 radiation lengths) preceded by a thin imaging section (3 radiation lengths) providing tracking and energy sampling. This paper follows our previous measurement of the iron spectrum [1] and it extends our investigation on the energy dependence of the spectral index of heavy elements. It reports the analysis of nickel data collected from November 2015 to May 2021 and a detailed assessment of the systematic uncertainties. In the region from 20 GeV/nto 240 GeV/n our present data are compatible within the errors with a single power law with spectral index−2.51±0.07.
Published: 2022
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12. Measurement of the Iron Spectrum in Cosmic Rays from 10 GeV/n to 2.0 TeV/n with the Calorimetric Electron Telescope on the International Space Station

Author: O Adriani, Y Akaike, K Asano, Y Asaoka, E Berti, G Bigongiari, W R Binns, M Bongi, P Brogi, Alessandro Bruno, J H Buckley, Nicholas Wade Cannady, G Castellini, C Checchia, M L Cherry, G Collazuol, K Ebisawa, H Fuke, S Gonzi, T Gregory Guzik, Thomas Hams, K Hibino, M Ichimura, K Ioka, W Ishizaki, M H Israel, K Kasahara, J Kataoka, R Kataoka, Y Katayose, C Kato, N Kawanaka, Y Kawakubo, K Kobayashi, K Kohri, J F Krizmanic, J T Link, J W Mitchell, A A Moiseev, G A De Nolfo, K Sakai, and M Sasaki
Subjects: Astrophysics
Abstract: The Calorimetric Electron Telescope (CALET), in operation on the International Space Station since 2015, collected a large sample of cosmic-ray iron over a wide energy interval. In this paper a measurement of the iron spectrum is presented in the range of kinetic energy per nucleon from 10GeV/n to 2.0 TeV/n allowing the inclusion of iron in the list of elements studied with unprecedented precision by space-borne instruments. The measurement is based on observations carried out from January 2016 to May 2020. The CALET instrument can identify individual nuclear species via a measurement of their electric charge with a dynamic range extending far beyond iron (up to atomic number Z = 40). The energy is measured by a homogeneous calorimeter with a total equivalent thickness of 1.2 proton interaction lengths preceded by a thin (3 radiation lengths) imaging section providing tracking and energy sampling. The analysis of the data and the detailed assessment of systematic uncertainties are described and results are compared with the findings of previous experiments. The observed differential spectrum is consistent within the errors with previous experiments. In the region from 50 GeV/n to 2 TeV/ n our present data are compatible with a single power law with spectral index−2.60±0.03.
Published: 2021
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13. Direct Measurement of the Cosmic-Ray Carbon and Oxygen Spectra from 10 GeV/n to 2.2 TeV/n with the Calorimetric Electron Telescope on the International Space Station

Author: O. Adriani, Y. Akaike, K. Asano, Y. Asaoka, M. G. Bagliesi, E. Berti, G. Bigongiari, W. R. Binns, M. Bongi, P. Brogi, A. Bruno, J. H. Buckley, N. Cannady, G. Castellini, C. Checchia, M. L. Cherry, G. Collazuol, K. Ebisawa, H. Fuke, S. Gonzi, T. G. Guzik, T. Hams, K. Hibino, M. Ichimura, K. Ioka, W. Ishizaki, M. H. Israel, K. Kasahara, J. Kataoka, R. Kataoka, Y. Katayose, C. Kato, N. Kawanaka, Y. Kawakubo, K. Kobayashi, K. Kohri, H. S. Krawczynski, J. F. Krizmanic, J. Link, P. Maestro, P. S. Marrocchesi, A. M. Messineo, J. W. Mitchell, S. Miyake, A. A. Moiseev, M. Mori, N. Mori, H. M. Motz, K. Munakata, S. Nakahira, J. Nishimura, G. A. De Nolfo, S. Okuno, J. F. Ormes, N. Ospina, S. Ozawa, L. Pacini, F. Palma, P. Papini, B. F. Rauch, S. B. Ricciarini, K. Sakai, T. Sakamoto, M. Sasaki, Y. Shimizu, A. Shiomi, R. Sparvoli, P. Spillantini, F. Stolzi, S. Sugita, J. E. Suh, A. Sulaj, M. Takita, T. Tamura, T. Terasawa, S. Torii, Y. Tsunesada, Y. Uchihori, E. Vannuccini, J. P. Wefel, K. Yamaoka, S. Yanagita, A. Yoshida, and K. Yoshida
Subjects: Astrophysics
Abstract: In this paper, we present the measurement of the energy spectra of carbon and oxygen in cosmic rays based on observations with the Calorimetric Electron Telescope on the International Space Station from October 2015 to October 2019. Analysis, including the detailed assessment of systematic uncertainties, and results are reported. The energy spectra are measured in kinetic energy per nucleon from 10 GeV/n to 2.2 TeV/n with an all-calorimetric instrument with a total thickness corresponding to 1.3 nuclear interaction length. The observed carbon and oxygen fluxes show a spectral index change of ∼0.15 around 200 GeV/n established with a significance > 3σ. They have the same energy dependence with a constant C/O flux ratio 0.911 ± 0.006 above 25 GeV/n. The spectral hardening is consistent with that measured by AMS-02, but the absolute normalization of the flux is about 27% lower, though in agreement with observations from previous experiments including the PAMELA spectrometer and the calorimetric balloon-borne experiment CREAM.
Published: 2020
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14. CALET on the International Space Station: the first three years of observations

Author: P Brogi, O Adriani, Y Akaike, K Asano, Y Asaoka, M G Bagliesi, E Berti, G Bigongiari, W R Binns, S Bonechi, M Bongi, A Bruno, J H Buckley, N Cannady, G Castellini, C Checchia, M L Cherry, G Collazuol, V Di Felice, K Ebisawa, H Fuke, T G Guzik, T Hams, K Hibino, M Ichimura, K Ioka, W Ishizaki, M H Israel, K Kasahara, J Kataoka, R Kataoka, Y Katayose, C Kato, N Kawanaka, Y Kawakubo, K Kohri, H S Krawczynski, J F Krizmanic, J Link, P Maestro, P S Marrocchesi, A M Messineo, J W Mitchell, S Miyake, A A Moiseev, M Mori, N. Mori, H M Motz, K Munakata, H Murakami, S Nakahira, J Nishimura, G A de Nolfo, S Okuno, J F Ormes, N Ospina, S Ozawa, L Pacini, F Palma, P Papini, B F Rauch, S B Ricciarini, K Saka, T Sakamoto, M Sasaki, Y Shimizu, A Shiomi, R Sparvoli, P Spillantini, F Stolzi, S Sugita, J E Suh, A Sulaj, I Takahashi, M Takita, T Tamura, T Terasawa, S Torii, Y Tsunesada, Y Uchihori, E Vannuccini, J P Wefel, K Yamaoka, S Yanagita, A Yoshida, and K Yoshida
Subjects: Instrumentation And Photography, Astrophysics
Abstract: The CALorimetric Electron Telescope CALET is a space instrument designed to carry out precision measurements of high energy cosmic-rays on the JEM-EF external platform on the International Space Station, where it has been collecting science data continuously since mid-October 2015. In addition to its primary goal of identifying nearby sources of high-energy electrons and possible signatures of dark matter in the electron spectrum, CALET is carrying out extensive measurements of the energy spectra, relative abundances and secondary-to-primary ratios of elements from proton to iron, and even above (up to Z = 40), studying the details of galactic particle propagation and acceleration. An overview of CALET based on the data taken during the first three years of observations is presented, including a direct measurement of the electron+positron energy spectrum from 11 GeV to 4.8 TeV. The proton spectrum has been measured from 50 GeV to 10 TeV covering, for the first time with a single space-borne instrument, the whole energy interval previously investigated in separate sub-ranges by magnetic spectrometers and calorimetric instruments. Preliminary spectra of cosmic-ray nuclei are also presented, together with gamma-ray observations and searches for an e.m. counterpart of LIGO/ Virgo GW events.
Published: 2020
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15. CALET Results after Three Years on the International Space Station

Author: Y Asaoka, O Adriani, Y Akaike, K Asano, M G Bagliesi, E Berti, G Bigongiari, W R Binns, S Bonechi, M Bongi, A Bruno, J H Buckley, N Cannady, G Castellini, C Checchia, M L Cherry, G Collazuol, V Di Felice, K Ebisawa, H Fuke, T G Guzik, T Hams, K Hibino, M Ichimura, K Ioka, W Ishizaki, M H Israel, K Kasahara, J Kataoka, R Kataoka, Y Katayose, C Kato, N Kawanaka, Y Kawakubo, K Kohri, H S Krawczynski, J F Krizmanic, J Link, P Maestro, P S Marrocchesi, A M Messineo, J W Mitchell, S Miyake, A A Moiseev, M Mori, H M Motz, K Munakata, S Nakahira, J Nishimura, G A De Nolfo, S Okuno, N Opsina, J F Ormes, S Ozawa, L Pacini, F Palma, V Pal'shin, P Papini, B F Rauch, S B Ricciarini, K Sakai, T Sakamoto, M Sasaki, Y Shimizu, A Shiomi, R Sparvoli, P Spillantini, F Stolzi, S Sugita, J E Suh, A Sulaj, I Takahashi, M Takita, T Tamura, T Terasawa, S Torii, Y Tsunesada, Y Uchihori, E Vannuccini, J P Wefel, K Yamaoka, S Yanagita, A Yoshida, and K Yoshida
Subjects: Astronomy
Abstract: The CALET (CALorimetric Electron Telescope) space experiment, which is currently conducting direct cosmic-ray observations onboard the International Space Station (ISS), is an all-calorimetric instrument optimized for cosmic-ray electron measurements with capability to measure hadrons and gamma-rays. Since the start of observation in October 2015, smooth and continuous operations have taken place. In this paper, we will give a brief summary of the CALET observations ranging from charged cosmic rays, gamma-rays, to space weather, while focusing on the energy spectra of electrons and protons.
Published: 2020
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16. Study of water Cherenkov detector to improve the angular resolution of an air-shower array for ultra-high-energy gamma-ray observation

Author: H. Nakada, A. Shiomi, M. Ohnishi, T. K. Sako, K. Hibino, and Y. Katayose
Subjects: Space and Planetary Science, Astronomy and Astrophysics
Published: 2022

17. The energy spectrum of cosmic rays measured by the Telescope Array using 10 years of fluorescence detector data

Author: R.U. Abbasi, Y. Abe, T. Abu-Zayyad, M. Allen, Y. Arai, R. Arimura, E. Barcikowski, J.W. Belz, D.R. Bergman, S.A. Blake, I. Buckland, B.G. Cheon, M. Chikawa, A. Fedynitch, T. Fujii, K. Fujisue, K. Fujita, R. Fujiwara, M. Fukushima, G. Furlich, Z. Gerber, N. Globus, W. Hanlon, N. Hayashida, H. He, R. Hibi, K. Hibino, R. Higuchi, K. Honda, D. Ikeda, N. Inoue, T. Ishii, H. Ito, D. Ivanov, A. Iwasaki, H.M. Jeong, S. Jeong, C.C.H. Jui, K. Kadota, F. Kakimoto, O. Kalashev, K. Kasahara, S. Kasami, S. Kawakami, K. Kawata, I. Kharuk, E. Kido, H.B. Kim, J.H. Kim, S.W. Kim, Y. Kimura, I. Komae, K. Komori, Y. Kusumori, M. Kuznetsov, Y.J. Kwon, K.H. Lee, M.J. Lee, B. Lubsandorzhiev, J.P. Lundquist, T. Matsuyama, J.A. Matthews, J.N. Matthews, R. Mayta, K. Miyashita, K. Mizuno, M. Mori, M. Murakami, I. Myers, S. Nagataki, K. Nakai, T. Nakamura, E. Nishio, T. Nonaka, S. Ogio, H. Ohoka, N. Okazaki, Y. Oku, T. Okuda, Y. Omura, M. Onishi, M. Ono, A. Oshima, H. Oshima, S. Ozawa, I.H. Park, K.Y. Park, M. Potts, M.S. Pshirkov, J. Remington, D.C. Rodriguez, C. Rott, G.I. Rubtsov, D. Ryu, H. Sagawa, R. Saito, N. Sakaki, T. Sako, N. Sakurai, D. Sato, K. Sato, S. Sato, K. Sekino, P.D. Shah, N. Shibata, T. Shibata, J. Shikita, H. Shimodaira, B.K. Shin, H.S. Shin, D. Shinto, J.D. Smith, P. Sokolsky, B.T. Stokes, T.A. Stroman, Y. Takagi, K. Takahashi, M. Takamura, M. Takeda, R. Takeishi, A. Taketa, M. Takita, Y. Tameda, K. Tanaka, M. Tanaka, S.B. Thomas, G.B. Thomson, P. Tinyakov, I. Tkachev, H. Tokuno, T. Tomida, S. Troitsky, R. Tsuda, Y. Tsunesada, S. Udo, F. Urban, I.A. Vaiman, D. Warren, T. Wong, K. Yamazaki, K. Yashiro, F. Yoshida, Y. Zhezher, and Z. Zundel
Subjects: Astronomy and Astrophysics
Published: 2023

18. KpFtsZ single filament

Author: J, Fujita, additional, H, Amesaka, additional, T, Yoshizawa, additional, K, Hibino, additional, N, Kamimura, additional, N, Kuroda, additional, T, Konishi, additional, Y, Kato, additional, M, Hara, additional, T, Inoue, additional, K, Namba, additional, SI, Tanaka, additional, and H, Matsumura, additional
Published: 2023
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19. KpFtsZ–Mb double helical tube

Author: J, Fujita, additional, H, Amesaka, additional, T, Yoshizawa, additional, K, Hibino, additional, N, Kamimura, additional, N, Kuroda, additional, T, Konishi, additional, Y, Kato, additional, M, Hara, additional, T, Inoue, additional, K, Namba, additional, SI, Tanaka, additional, and H, Matsumura, additional
Published: 2023
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20. Direct Measurement of the Cosmic-Ray Proton Spectrum from 50 GeV to 10 TeV with the Calorimetric Electron Telescope on the International Space Station

Author: O. Adriani, Y. Akaike, K. Asano, Y. Asaoka, M. G. Bagliesi, E. Berti, G. Bigongiari, W. R. Binns, S. Bonechi, M. Bongi, P. Brogi, A. Bruno, J. H. Buckley, N. Cannady, G. Castellini, C. Checchia, M. L. Cherry, G. Collazuol, V. Di Felice, K. Ebisawa, H. Fuke, T. G. Guzik, T. Hams, N. Hasebe, K. Hibino, M. Ichimura, K. Ioka, W. Ishizaki, M. H. Israel, K. Kasahara, J. Kataoka, R. Kataoka, Y. Katayose, C. Kato, N. Kawanaka, Y. Kawakubo, K. Kohri, H. S. Krawczynski, J. F. Krizmanic, T. Lomtadze, P. Maestro, P. S. Marrocchesi, A. M. Messineo, J. W. Mitchell, S. Miyake, A. A. Moiseev, K. Mori, M. Mori, N. Mori, H. M. Motz, K. Munakata, H. Murakami, S. Nakahira, J. Nishimura, G. A. de Nolfo, S. Okuno, J. F. Ormes, S. Ozawa, L. Pacini, F. Palma, P. Papini, A. V. Penacchioni, B. F. Rauch, S. B. Ricciarini, K. Sakai, T. Sakamoto, M. Sasaki, Y. Shimizu, A. Shiomi, R. Sparvoli, P. Spillantini, F. Stolzi, J. E. Suh, A. Sulaj, I. Takahashi, M. Takayanagi, M. Takita, T. Tamura, T. Terasawa, H. Tomida, S. Torii, Y. Tsunesada, Y. Uchihori, S. Ueno, E. Vannuccini, J. P. Wefel, K. Yamaoka, S. Yanagita, A. Yoshida, and K. Yoshida
Published: 2019
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21. The CALorimetric Electron Telescope (CALET) on the International Space Station: Results from the First Two Years On Orbit

Author: Y Asaoka, O Adriani, Yosui Akaike, Katsuaki Asano, M G Bagliesi, E Berti, G Bigongiari, W R Binns, S Bonechi, M Bongi, A Bruno, Paolo Brogi, J H Buckley, N Cannady, G Castellini, C Checchia, M L Cherry, G Collazuol, V Di Felice, K Ebisawa, Hideyuki Fuke, T Gregory Guzik, T Hams, N Hasebe, K Hibino, M Ichimura, K Ioka, W Ishizaki, M H Israel, K Kasahara, J Kataoka, R Kataoka, Y Katayose, C Kato, N Kawanaka, Y Kawakubo, K Kohri, H S Krawczynski, John F Krizmanic, T Lomtadze, Paolo Maestro, P S Marrocchesi, A M Messineo, John W Mitchell, S Miyake, Alexander A Moiseev, K Mori, M Mori, N Mori, H M Motz, K Munakata, H Murakami, Satoshi Nakahira, J Nishimura, Georgia Adair De Nolfo, James O Okuno, J F Ormes, S Ozawa, L Pacini, F Palma, V Pal’shin, P Papini, A V Penacchioni, B F Rauch, S B Ricciarini, Kenichi Sakai, Takuma Sakamoto, M Sasaki, A Shiomi, R Sparvoli, P Spillantini, F Stolzi, S Sugita, J E Suh, A Sulaj, I Takahashi, M Takayanagi, M Takita, Takumi Tamura, N Tateyama, T Terasawa, H Tomida, S Torii, Yoshiki Tsunesada, Y Uchihori, S Ueno, E Vannuccini, J P Wefel, K Yamaoka, S Yanagita, A Yoshida, K Yoshida, and Y Shimizu
Subjects: Physics Of Elementary Particles And Fields
Abstract: The CALorimetric Electron Telescope (CALET) is a high-energy astroparticle physics space experiment installed on the International Space Station (ISS), developed and operated by Japan in collaboration with Italy and the United States. The CALET mission goals include the investigation of possible nearby sources of high-energy electrons, of the details of galactic particle acceleration and propagation, and of potential signatures of dark matter. CALET measures the cosmic-ray electron+positron flux up to 20 TeV, gamma-rays up to 10 TeV, and nuclei with Z=1 to 40 up to 1,000 TeV for the more abundant elements during a long-term observation aboard the ISS. Starting science operation in mid-October 2015, CALET performed continuous observation without major interruption with close to 20 million triggered events over 10 GeV per month. Based on the data taken during the �rst two-years, we present an overview of CALET observations: 1) Electron+positron energy spectrum, 2) Nuclei analysis, 3) Gamma-ray observation including a characterization of on-orbit performance. Results of the electromagnetic counterpart search for LIGO/Virgo gravitational wave events are discussed as well.
Published: 2019
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22. Detectability of southern gamma-ray sources beyond 100 TeV with ALPAQUITA, the prototype experiment of ALPACA

Author: Masaki Nishizawa, W. Kihara, T. Ohura, To. Saito, Tatsumi Koi, M. Subieta, K. Yamazaki, Shoichi Ogio, N. Tajima, Y. Katayose, A. Gomi, S. Udo, Y. Nakamura, S. Okukawa, Y. Nakazawa, T. Sako, N. Hotta, Harufumi Tsuchiya, S. Shibata, Shigeaki Kato, H. Kojima, E. De la Fuente, K. Hibino, D. Kurashige, Akitoshi Oshima, M. Raljevich, K. Tanaka, C. Nina, H. Rivera, I. Toledano-Juarez, Kazumasa Kawata, A. Shiomi, W. Takano, F. Orozco-Luna, H. Nakada, Takashi Sako, R. Mayta, H. Torres, C. A. H. Condori, Y. Ko, P. Miranda, Kazuoki Munakata, J. Lozoya, Y. Yokoe, Yoshiki Tsunesada, Chihiro Kato, M. Ohnishi, R. Ticona, Yuichiro Tameda, and Masato Takita
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Monte Carlo method, Gamma ray, FOS: Physical sciences, Astronomy, Astronomy and Astrophysics, Cosmic ray, Particle detector, Data acquisition, Air shower, Space and Planetary Science, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Cherenkov radiation, Muon detector
Abstract: Andes Large-area PArticle detector for Cosmic-ray physics and Astronomy (ALPACA) is an international experiment that applies southern very-high-energy (VHE) gamma-ray astronomy to determine the origin of cosmic rays around the knee energy region ($10^{15}\, {\rm eV} - 10^{16}\, {\rm eV}$). The experiment consists of an air shower (AS) array with a surface of $83, 000\, {\rm m}^2$ and an underground water Cherenkov muon detector (MD) array covering $5, 400\, {\rm m}^2$. The experimental site is at the Mt. Chacaltaya plateau in La Paz, Bolivia, with an altitude of $4, 740\, {\rm m}$ corresponding to $572\, {\rm g}/{\rm cm}^2$ atmospheric thickness. As the prototype experiment of ALPACA, the ALPAQUITA experiment aims to begin data acquisition in late 2021. The ALPAQUITA array consists of a smaller AS array ($18, 450\, {\rm m}^2$) and underground MD ($900\, {\rm m}^2$), which are now under construction. ALPAQUITA's sensitivity to gamma-ray sources is evaluated with Monte Carlo simulations. The simulation finds that five gamma-ray sources observed by H.E.S.S. and HAWC experiments will be detected by ALPAQUITA beyond 10 TeV and one out of these five - HESS J1702-420A - above 300 TeV in one calendar year observation. The latter finding means that scientific discussions can be made on the emission mechanism of gamma rays beyond 100 TeV from southern sources on the basis of the observational results of this prototype experiment., This is the manuscript accepted by Experimental Astronomy. For the published article, see https://doi.org/10.1007/s10686-021-09796-8
Published: 2021

23. ALPACA experiment: A new air shower array to explore the sub-PeV gamma-ray sky in the southern hemisphere

Author: Takashi Sako, M. Anzorena, A. Gomi, Y. Hayashi, K. Hibino, N. Hotta, A Jimenez-Meza, Y. Katayose, C. Kato, S. Kato, I. Kawahara, T. Kawashima, K. Kawata, T. Koi, H. Kojima, D. Kurashige, R. Mayta, P. Miranda, K. Munakata, K. Nagaya, Y. Nakamura, C. Nina, M. Nishizawa, R. Noguchi, S. Ogio, M. Ohnishi, S. Okukawa, A. Oshima, M. Raljevich, H. Rivera, T. Saito, Y. Sakakibara, T. Sasaki, S. Shibata, A. Shiomi, M. Subieta, N. Tajima, W. Takano, M. Takita, Y. Tameda, K. Tanaka, R. Ticona, I. Toledano-Juarez, H. Tsuchiya, Y. Tsunesada, S. Udo, K. Yamazaki, Y. Yokoe, C.A.H. Condori, Eduardo de la Fuente, and T. K. Sako
Published: 2022

24. Extended Measurement of the Cosmic-Ray Electron and Positron Spectrum from 11 GeV to 4.8 TeV with the Calorimetric Electron Telescope on the International Space Station

Author: O. Adriani, Y. Akaike, K. Asano, Y. Asaoka, M. G. Bagliesi, E. Berti, G. Bigongiari, W. R. Binns, S. Bonechi, M. Bongi, P. Brogi, J. H. Buckley, N. Cannady, G. Castellini, C. Checchia, M. L. Cherry, G. Collazuol, V. Di Felice, K. Ebisawa, H. Fuke, T. G. Guzik, T. Hams, M. Hareyama, N. Hasebe, K. Hibino, M. Ichimura, K. Ioka, W. Ishizaki, M. H. Israel, K. Kasahara, J. Kataoka, R. Kataoka, Y. Katayose, C. Kato, N. Kawanaka, Y. Kawakubo, K. Kohri, H. S. Krawczynski, J. F. Krizmanic, T. Lomtadze, P. Maestro, P. S. Marrocchesi, A. M. Messineo, J. W. Mitchell, S. Miyake, A. A. Moiseev, K. Mori, M. Mori, N. Mori, H. M. Motz, K. Munakata, H. Murakami, S. Nakahira, J. Nishimura, G. A. de Nolfo, S. Okuno, J. F. Ormes, S. Ozawa, L. Pacini, F. Palma, P. Papini, A. V. Penacchioni, B. F. Rauch, S. B. Ricciarini, K. Sakai, T. Sakamoto, M. Sasaki, Y. Shimizu, A. Shiomi, R. Sparvoli, P. Spillantini, F. Stolzi, J. E. Suh, A. Sulaj, I. Takahashi, M. Takayanagi, M. Takita, T. Tamura, N. Tateyama, T. Terasawa, H. Tomida, S. Torii, Y. Tsunesada, Y. Uchihori, S. Ueno, E. Vannuccini, J. P. Wefel, K. Yamaoka, S. Yanagita, A. Yoshida, and K. Yoshida
Published: 2018
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25. Hadronic Interaction Model Dependence in Cosmic Gamma-ray Flux Estimation Using an Extensive Air Shower Array with a Muon Detector

Author: S. Okukawa, M. Anzorena, S. Asano, C. A. H. Condori, E. de la Fuente, A. Gomi, K. Hibino, N. Hotta, A. Jimenez-Meza, Y. Katayose, C. Kato, S. Kato, T. Kawashima, K. Kawata, T. Koi, H. Kojima, D. Kurashige, J. Lozoya, R. Mayta, P. Miranda, K. Munakata, K. Nagaya, Y. Nakamura, Y. Nakazawa, C. Nina, M. Nishizawa, S. Ogio, M. Ohnishi, A. Oshima, M. Raljevic, H. Rivera, T. Saito, Y. Sakakibara, T. Sako, T. K. Sako, S. Shibata, A. Shiomi, M. Subieta, N. Tajima, W. Takano, M. Takita, Y. Tameda, K. Tanaka, R. Ticona, I. Toledano-Juarez, H. Tsuchiya, Y. Tsunesada, S. Udo, K. Yamazaki, and Y. Yokoe
Subjects: Space and Planetary Science, Astronomy and Astrophysics
Abstract: Observation techniques of high-energy gamma rays using air showers have remarkably progressed via the Tibet AS$\gamma$, HAWC, and LHAASO experiments. These observations have significantly contributed to gamma-ray astronomy in the northern sky's sub-Peta electron volts (PeV) region. Moreover, in the southern sky, the ALPACA experiment is underway at 4,740\,m altitude on the Chacaltaya plateau in Bolivia. This experiment estimates the gamma-ray flux from the difference between the number of on-source and off-source events by real data, utilizing the gamma-ray detection efficiency calculated through Monte Carlo simulations, which in turn depends on the hadronic interaction models. Even though the number of cosmic-ray background events can be experimentally estimated, this model dependence affects the estimation of gamma-ray detection efficiency. However, previous reports have assumed that the model dependence is negligible and have not included it in the error of gamma-ray flux estimation. Using ALPAQUITA, the prototype experiment of ALPACA, we quantitatively evaluated the model dependence on hadronic interaction models for the first time. We evaluate the model dependence on hadronic interactions as less than 3.6\,\% in the typical gamma-ray flux estimation performed by ALPAQUITA; this is negligible compared with other uncertainties such as energy scale uncertainty in the energy range from 6 to 300 TeV, which is dominated by the Monte Carlo statistics. This upper limit of 3.6\,\% model dependence is expected to apply to ALPACA.
Published: 2022

26. CALET Search for electromagnetic counterparts of gravitational waves during the LIGO/Virgo O3 run

Author: O. Adriani, Y. Akaike, K. Asano, Y. Asaoka, E. Berti, G. Bigongiari, W. R. Binns, M. Bongi, P. Brogi, A. Bruno, J. H. Buckley, N. Cannady, G. Castellini, C. Checchia, M. L. Cherry, G. Collazuol, K. Ebisawa, A. W. Ficklin, H. Fuke, S. Gonzi, T. G. Guzik, T. Hams, K. Hibino, M. Ichimura, K. Ioka, W. Ishizaki, M. H. Israel, K. Kasahara, J. Kataoka, R. Kataoka, Y. Katayose, C. Kato, N. Kawanaka, Y. Kawakubo, K. Kobayashi, K. Kohri, H. S. Krawczynski, J. F. Krizmanic, P. Maestro, P. S. Marrocchesi, A. M. Messineo, J. W. Mitchell, S. Miyake, A. A. Moiseev, M. Mori, N. Mori, H. M. Motz, K. Munakata, S. Nakahira, J. Nishimura, G. A. de Nolfo, S. Okuno, J. F. Ormes, N. Ospina, S. Ozawa, L. Pacini, P. Papini, B. F. Rauch, S. B. Ricciarini, K. Sakai, T. Sakamoto, M. Sasaki, Y. Shimizu, A. Shiomi, P. Spillantini, F. Stolzi, S. Sugita, A. Sulaj, M. Takita, T. Tamura, T. Terasawa, S. Torii, Y. Tsunesada, Y. Uchihori, E. Vannuccini, J. P. Wefel, K. Yamaoka, S. Yanagita, A. Yoshida, K. Yoshida, and W. V. Zober
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Space and Planetary Science, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Gamma-ray astronomy Gamma-ray bursts Gravitational wave sources Gamma-ray transient sources, Astronomy and Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract: The CALorimetric Electron Telescope (CALET) on the International Space Station (ISS) consists of a high-energy cosmic ray CALorimeter (CAL) and a lower-energy CALET Gamma ray Burst Monitor (CGBM). CAL is sensitive to electrons up to 20 TeV, cosmic ray nuclei from Z = 1 through Z $\sim$ 40, and gamma rays over the range 1 GeV - 10 TeV. CGBM observes gamma rays from 7 keV to 20 MeV. The combined CAL-CGBM instrument has conducted a search for gamma ray bursts (GRBs) since Oct. 2015. We report here on the results of a search for X-ray/gamma ray counterparts to gravitational wave events reported during the LIGO/Virgo observing run O3. No events have been detected that pass all acceptance criteria. We describe the components, performance, and triggering algorithms of the CGBM - the two Hard X-ray Monitors (HXM) consisting of LaBr$_{3}$(Ce) scintillators sensitive to 7 keV to 1 MeV gamma rays and a Soft Gamma ray Monitor (SGM) BGO scintillator sensitive to 40 keV to 20 MeV - and the high-energy CAL consisting of a CHarge-Detection module (CHD), IMaging Calorimeter (IMC), and fully active Total Absorption Calorimeter (TASC). The analysis procedure is described and upper limits to the time-averaged fluxes are presented., 27 pages, 10 figures. Accepted for publication in ApJ
Published: 2022

27. ПОИСК НЕЙТРИНО УЛЬТРАВЫСОКИХ ЭНЕРГИЙ ПО ДАННЫМ НАЗЕМНОЙ РЕШЕТКИ ЭКСПЕРИМЕНТА TELESCOPE ARRAY

Author: Taka Tomida, J. Remington, Kenta Yashiro, Yasunori Saito, M. Abe, O. Kalashev, Jonathan Smith, Takeshi Okuda, Igor Tkachev, N. Inoue, M. Ohnishi, Federico R. Urban, Yuichiro Tameda, H. Oda, Akimichi Taketa, T. Suzawa, Naoaki Hayashida, Shingo Kawana, Yasuhiro H. Takahashi, John N. Matthews, Isaac Myers, Vladim Kuzmin, William Hanlon, Elliott Barcikowski, Seok Ho Jeong, K. Nagasawa, B. G. Cheon, Hidemi Ito, Fumiya Shibata, Zach Zundel, J. Yang, S. Kitamura, Dmitri Ivanov, Keijiro Mukai, R. Sahara, John Belz, Y. J. Kwon, Hideyuki Ohoka, Fumio Kakimoto, Toshiyuki Nonaka, Toshitsugu Fujii, Daisuke Ikeda, R. Ishimori, Yuta Tanoue, D. R. Bergman, S. R. Stratton, G. Furlich, Takaaki Ishii, Tiffany Wong, Hideki Tanaka, K. Kadota, Inkyu Park, Motoki Hayashi, Hisono Tokuno, T. K. Sako, J. P. Lundquist, D. C. Rodriguez, Ben Stokes, Toru Nakamura, K. Yamazaki, Hongsu Kim, S. B. Thomas, Masahiro Fukushima, S. Kawakami, K. Hibino, Pierre Sokolsky, Ryo Nakamura, K. H. Lee, Jihee Kim, T.-A. Shibata, Eiji Kido, M. V. Kuznetsov, Kazuhiro Machida, Hiroshi Yamaoka, Keitaro Fujita, M. Takeda, Shigehiro Nagataki, Yana Zhezher, Y. Uchihori, Kei Nakai, Kohei Yada, Gordon Thomson, Tom Stroman, Robert Cady, Kazuo Saito, Charlie Jui, BayarJon Paul Lubsandorzhiev, Hiroyuki Sagawa, Mayuko Minamino, Michiyuki Chikawa, K. Honda, Yasunori Kitamura, Grigory Rubtsov, Masaaki Tanaka, Kalen Martens, M. Takita, H. Yoshii, Bokkyun Shin, Koichi Sekino, Kiyoshi Tanaka, Maxim Pshirkov, Jyunsei Chiba, P. Tinyakov, Dongsu Ryu, Y. Omura, Mai Takamura, Y. Takagi, Samuel Blake, Shoichi Ogio, Priti Shah, Ryuji Takeishi, J. Ogura, M. Allen, K. Kasahara, Shoichi Kishigami, Akitoshi Oshima, Y. Tsunesada, Hideaki Shimodaira, Hyoming Jeong, Masaomi Ono, K. Tsutsumi, Rasha Abbasi, Tareq Abu-Zayyad, L. M. Scott, Y. Hayashi, K. Kawata, M. Yamamoto, Nobuyuki Sakurai, Ryota Onogi, J. H. Kim, A. Di Matteo, Ryota Fujiwara, R. Mayta, Heungsu Shin, Naoto Sakaki, Shigeharu Udo, R. Azuma, H. Kawai, T. Seki, T. Matsuyama, S. Ozawa, and Sergey Troitsky
Subjects: General Physics and Astronomy
Published: 2020

28. Cosmic-Ray Boron Flux Measured from 8.4 GeV/n to 3.8 TeV/n with the Calorimetric Electron Telescope on the International Space Station

Author: O, Adriani, Y, Akaike, K, Asano, Y, Asaoka, E, Berti, G, Bigongiari, W R, Binns, M, Bongi, P, Brogi, A, Bruno, J H, Buckley, N, Cannady, G, Castellini, C, Checchia, M L, Cherry, G, Collazuol, G A, de Nolfo, K, Ebisawa, A W, Ficklin, H, Fuke, S, Gonzi, T G, Guzik, T, Hams, K, Hibino, M, Ichimura, K, Ioka, W, Ishizaki, M H, Israel, K, Kasahara, J, Kataoka, R, Kataoka, Y, Katayose, C, Kato, N, Kawanaka, Y, Kawakubo, K, Kobayashi, K, Kohri, H S, Krawczynski, J F, Krizmanic, P, Maestro, P S, Marrocchesi, A M, Messineo, J W, Mitchell, S, Miyake, A A, Moiseev, M, Mori, N, Mori, H M, Motz, K, Munakata, S, Nakahira, J, Nishimura, S, Okuno, J F, Ormes, S, Ozawa, L, Pacini, P, Papini, B F, Rauch, S B, Ricciarini, K, Sakai, T, Sakamoto, M, Sasaki, Y, Shimizu, A, Shiomi, P, Spillantini, F, Stolzi, S, Sugita, A, Sulaj, M, Takita, T, Tamura, T, Terasawa, S, Torii, Y, Tsunesada, Y, Uchihori, E, Vannuccini, J P, Wefel, K, Yamaoka, S, Yanagita, A, Yoshida, K, Yoshida, and W V, Zober
Abstract: We present the measurement of the energy dependence of the boron flux in cosmic rays and its ratio to the carbon flux in an energy interval from 8.4 GeV/n to 3.8 TeV/n based on the data collected by the Calorimetric Electron Telescope (CALET) during ∼6.4 yr of operation on the International Space Station. An update of the energy spectrum of carbon is also presented with an increase in statistics over our previous measurement. The observed boron flux shows a spectral hardening at the same transition energy E_{0}∼200 GeV/n of the C spectrum, though B and C fluxes have different energy dependences. The spectral index of the B spectrum is found to be γ=-3.047±0.024 in the interval 25E200 GeV/n. The B spectrum hardens by Δγ_{B}=0.25±0.12, while the best fit value for the spectral variation of C is Δγ_{C}=0.19±0.03. The B/C flux ratio is compatible with a hardening of 0.09±0.05, though a single power-law energy dependence cannot be ruled out given the current statistical uncertainties. A break in the B/C ratio energy dependence would support the recent AMS-02 observations that secondary cosmic rays exhibit a stronger hardening than primary ones. We also perform a fit to the B/C ratio with a leaky-box model of the cosmic-ray propagation in the Galaxy in order to probe a possible residual value λ_{0} of the mean escape path length λ at high energy. We find that our B/C data are compatible with a nonzero value of λ_{0}, which can be interpreted as the column density of matter that cosmic rays cross within the acceleration region.
Published: 2022

29. Study of water Cherenkov detector to determine air shower arrival directions with accuracy

Author: Y. Katayose, Hiroki Nakada, M. Ohnishi, K. Hibino, A. Shiomi, and Takashi Sako
Subjects: Physics, Physics::Instrumentation and Detectors, Cherenkov detector, business.industry, Astrophysics::High Energy Astrophysical Phenomena, Monte Carlo method, Astrophysics::Instrumentation and Methods for Astrophysics, Gamma ray, Cosmic ray, Radius, Secondary electrons, law.invention, Air shower, Optics, law, High Energy Physics::Experiment, Angular resolution, business
Abstract: Experiments with high angular resolution that can detect gamma rays in the 100 TeV region will help study acceleration mechanisms of gamma-ray sources with morphological characteristics. In recent years, three groups using extensive air-shower (AS) arrays have reported detecting gamma rays in the 100 TeV region from celestial bodies in the galaxy. In extensive air shower experiments, an arrival direction of a cosmic ray is determined by estimating a shape of a front surface of an air shower based on the density distribution and detection time of secondary particles. The density of secondary gamma rays of an air shower is several times that of secondary electrons and positrons in an air shower and the difference increases as the distance from the shower axis increases. Therefore, increasing the sensitivity to detect secondary gamma rays plays an important role in determining the arrival direction of the shower. Monte Carlo simulation was used to investigate the effect of secondary gamma rays on the time determination accuracy of the air shower front. When an AS array capable of measuring secondary gamma rays with 100% sensitivity was installed at an altitude of 4,740 m, the angular resolution for a 500 TeV shower was improved by about 40% compared to an array that could observe only secondary electrons and positrons. The optimum shape of the water Cherenkov detector (WCD), which is highly sensitive to gamma rays, was investigated by Monte Carlo simulation. When a water tank with a radius of 4.5 m and PMTs with a diameter of 8 inches was used, it was found that about 19 PMTs (area ratio of approximately 0.01) were suitable for detection efficiency and timing response at a water depth of 1.6 m.
Published: 2021

30. Investigating the Vela SNR's Emission of Electron Cosmic Rays with CALET at the International Space Station

Author: John F. Krizmanic, A. Sulaj, S. Miyake, P. Spillantini, Holger Motz, Y. Katayose, M. Takita, S. Sugita, Ryuho Kataoka, K. Kobayashi, W.V. Zober, O. Adriani, K. Ebisawa, Y. Tsunesada, Gabriele Bigongiari, Kazutaka Yamaoka, Kunihito Ioka, Eugenio Berti, A. Yoshida, J. P. Wefel, L. Pacini, J. F. Ormes, Michael Cherry, T. Sakamoto, A. A. Moiseev, M. Ichimura, Jason Link, Shoji Torii, A.W. Ficklin, Jun Kataoka, Yoichi Asaoka, Masaki Mori, Katsuaki Asano, Thomas Hams, S. Ozawa, P. S. Marrocchesi, John Mitchell, Jun Nishimura, Sandro Gonzi, Y. Akaike, M. H. Israel, F. Stolzi, Henric Krawczynski, Y. Shimizu, N. Ospina, H. Fuke, Paolo Brogi, K. Sakai, Chihiro Kato, Kazunori Kohri, M. Bongi, S. Okuno, A. Shiomi, N. Mori, Y. Uchihori, N. Cannady, K. Hibino, W. R. Binns, T. Tamura, M. Sasaki, G. Castellini, G. Collazuol, K. Kasahara, T. G. Guzik, J. H. Buckley, Shohei Yanagita, Satoshi Nakahira, Y. Kawakubo, A. Bruno, W. Ishizaki, Alberto Messineo, C. Checchia, S. B. Ricciarini, Kazuoki Munakata, P. Papini, E. Vannuccini, Toshio Terasawa, Kenji Yoshida, Paolo Maestro, G. A. de Nolfo, Norita Kawanaka, and Brian Rauch
Subjects: Physics, Astrophysics::High Energy Astrophysical Phenomena, Flux, Cosmic ray, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Electron, Vela, law.invention, Telescope, Supernova, Positron, Pulsar, law, Astrophysics::Galaxy Astrophysics
Abstract: The ISS-based Calorimetric Electron Telescope (CALET) is directly measuring the energy spec- trum of electron+positron cosmic rays up to 20 TeV. Cosmic-ray electrons of TeV region energy are limited by energy loss to a propagation range of about 1 kpc, therefore the expected sources are a few nearby supernova remnants (SNR), with the Vela SNR dominating the spectrum. The latest spectrum measured by CALET in combination with the positron-only flux published by AMS-02 is fitted with a comprehensive model including nearby pulsars as the source of the positron excess. This model is extended to the TeV region by addition of the flux from the Vela SNR as calculated with DRAGON, with the integrated energy emitted in electron cosmic rays by the SNR as a variable scale factor. Exploring various scenarios for the time and energy dependence of the cosmic-ray release from Vela, under varied propagation conditions, best-fitting interpretations of the spectrum and upper limits on the emission of cosmic-ray electrons by Vela have been derived.
Published: 2021

31. A simulation study on the performance of the ALPAQUITA experiment

Author: N. Hotta, N. Tajima, S Asano, S. Okukawa, J L Garcia-Luna, M. Subieta, Chihiro Kato, Y. Yokoe, Y. Nakamura, To. Saito, W. Takano, K Nagaya, R. Mayta, Y. Katayose, R. Ticona, M. Ohnishi, Akitoshi Oshima, M. Raljevich, F Aceves de la Cruz, Sei Kato, S. Udo, Masaki Nishizawa, Kazuoki Munakata, K. Yamazaki, F Orozco, A. Gomi, K. Tanaka, C. Nina, T. K. Sako, Shoichi Shibata, Y. Nakazawa, K. Hibino, P. Miranda, E de la Fuente, A. Shiomi, Shoichi Ogio, Yuichiro Tameda, Y Sakakibara, D. Kurashige, T Kawashima, H. Kojima, A. Jiménez-Meza, Masato Takita, K. Kawata, J. Lozoya, Harufumi Tsuchiya, H. Rivera, I. Toledano-Juarez, Y. Tsunesada, and Tatsumi Koi
Subjects: Physics, Particle physics, Physics::Instrumentation and Detectors, Astrophysics::High Energy Astrophysical Phenomena, media_common.quotation_subject, Monte Carlo method, Detector, Gamma ray, Cosmic ray, Air shower, Sky, High Energy Physics::Experiment, Sensitivity (control systems), Energy (signal processing), media_common
Abstract: The ALPACA experiment is a new air shower experiment mainly aiming to explore the southern sky in the VHE gamma-ray regime beyond 100 TeV. As the prototype experiment, ALPAQUITA will start in late 2021. It consists of a surface air shower array (18,450 ${\rm m}^2$) and an underground muon detector array (900 ${\rm m}^2$). In this study, the performance of ALPAQUITA including the sensitivity to gamma-ray point sources is investigated using a Monte Carlo simulation to quantitatively evaluate the possibility of detection of gamma-ray sources in the prototype phase. Corsika 7.6400 and Geant4 v10.04.p02 are used to simulate air shower development in the atmosphere and detector response, respectively. The output data are then processed and analyzed in the same way as the experiment. As a result, the study finds that the air shower array has an energy resolution of $\pm21\%$ and the angular resolution of $\simeq 0.2^{\circ}$ for gamma rays with an energy of 100 TeV. The detection area of the air shower array for gamma rays reaches $\simeq 12, 600 \, {\rm m}^2$ above $\simeq 10\, {\rm TeV}$. The muon detector rejects $\simeq 99.9\%$ of background cosmic rays and maintains $\simeq 80\%$ of signal gamma rays. This high discrimination power will enable the detection of five southern known gamma-ray sources beyond 30 TeV and the extension of the energy spectrum of one out of the five, HESS J1702-420A, up to $\simeq 300\, {\rm TeV}$ during one calendar year observation. This study concludes that ALPAQUITA will provide data enough to discuss a hot topic of VHE gamma-ray astronomy before passing the baton to ALPACA.
Published: 2021

32. Measurement of the Iron Spectrum in Cosmic Rays from 10 GeV/n to 2.0 TeV/n with the Calorimetric Electron Telescope on the International Space Station

Author: Toshio Terasawa, Kazunori Kohri, Yoichi Asaoka, A. Bruno, Katsuaki Asano, Masato Takita, W. Ishizaki, Alberto Messineo, K. Kobayashi, Y. Shimizu, Kazutaka Yamaoka, M. Bongi, Paolo Maestro, Y. Tsunesada, Gabriele Bigongiari, Eugenio Berti, A. Yoshida, Satoshi Sugita, Ryuho Kataoka, N. Ospina, J. Link, A. A. Moiseev, Y. Kawakubo, Henric Krawczynski, F. Stolzi, Norita Kawanaka, Chihiro Kato, M. Sasaki, Kenji Yoshida, H. Fuke, Paolo Brogi, S. Ozawa, G. Castellini, O. Adriani, Shohei Yanagita, J. F. Ormes, Shoji Torii, Katsuaki Kasahara, Brian Rauch, Kunihito Ioka, Satoshi Nakahira, T. Tamura, K. Ebisawa, K. Hibino, W. R. Binns, Sandro Gonzi, M. Ichimura, S. Okuno, S. Miyake, M. H. Israel, Y. Katayose, P. Spillantini, Michael Cherry, J. P. Wefel, Yosui Akaike, Masaki Mori, C. Checchia, John Mitchell, Jun Kataoka, T. Sakamoto, Jun Nishimura, A. Shiomi, K. Sakai, Kazuoki Munakata, P. S. Marrocchesi, John F. Krizmanic, A. Sulaj, G. Collazuol, G. A. de Nolfo, N. Cannady, N. Mori, Y. Uchihori, Holger Motz, T. G. Guzik, J. H. Buckley, L. Pacini, S. B. Ricciarini, T. Hams, P. Papini, and E. Vannuccini
Subjects: Physics, Spectral index, Proton, Astrophysics::High Energy Astrophysical Phenomena, General Physics and Astronomy, Cosmic ray, Kinetic energy, 01 natural sciences, law.invention, Calorimeter, Telescope, Nuclear physics, law, 0103 physical sciences, Atomic number, 010306 general physics, Nucleon
Abstract: The Calorimetric Electron Telescope (CALET), in operation on the International Space Station since 2015, collected a large sample of cosmic-ray iron over a wide energy interval. In this Letter a measurement of the iron spectrum is presented in the range of kinetic energy per nucleon from 10 GeV/n to 2.0 TeV/n allowing the inclusion of iron in the list of elements studied with unprecedented precision by space-borne instruments. The measurement is based on observations carried out from January 2016 to May 2020. The CALET instrument can identify individual nuclear species via a measurement of their electric charge with a dynamic range extending far beyond iron (up to atomic number Z=40). The energy is measured by a homogeneous calorimeter with a total equivalent thickness of 1.2 proton interaction lengths preceded by a thin (3 radiation lengths) imaging section providing tracking and energy sampling. The analysis of the data and the detailed assessment of systematic uncertainties are described and results are compared with the findings of previous experiments. The observed differential spectrum is consistent within the errors with previous experiments. In the region from 50 GeV/n to 2 TeV/n our present data are compatible with a single power law with spectral index -2.60±0.03.
Published: 2021

33. Measurement of the Gamma-Ray Energy Spectrum beyond 100 TeV from the HESS J1843–033 Region

Author: M. Amenomori, S. Asano, Y. W. Bao, X. J. Bi, D. Chen, T. L. Chen, W. Y. Chen, Xu Chen, Y. Chen, null Cirennima, S. W. Cui, null Danzengluobu, L. K. Ding, J. H. Fang, K. Fang, C. F. Feng, Zhaoyang Feng, Z. Y. Feng, Qi Gao, A. Gomi, Q. B. Gou, Y. Q. Guo, Y. Y. Guo, H. H. He, Z. T. He, K. Hibino, N. Hotta, Haibing Hu, H. B. Hu, K. Y. Hu, J. Huang, H. Y. Jia, L. Jiang, P. Jiang, H. B. Jin, K. Kasahara, Y. Katayose, C. Kato, S. Kato, T. Kawashima, K. Kawata, M. Kozai, D. Kurashige, null Labaciren, G. M. Le, A. F. Li, H. J. Li, W. J. Li, Y. Li, Y. H. Lin, B. Liu, C. Liu, J. S. Liu, L. Y. Liu, M. Y. Liu, W. Liu, X. L. Liu, Y.-Q. Lou, H. Lu, X. R. Meng, Y. Meng, K. Munakata, K. Nagaya, Y. Nakamura, Y. Nakazawa, H. Nanjo, C. C. Ning, M. Nishizawa, M. Ohnishi, S. Okukawa, S. Ozawa, L. Qian, X. Qian, X. L. Qian, X. B. Qu, T. Saito, Y. Sakakibara, M. Sakata, T. Sako, T. K. Sako, J. Shao, M. Shibata, A. Shiomi, H. Sugimoto, W. Takano, M. Takita, Y. H. Tan, N. Tateyama, S. Torii, H. Tsuchiya, S. Udo, H. Wang, Y. P. Wang, null Wangdui, H. R. Wu, Q. Wu, J. L. Xu, L. Xue, Z. Yang, Y. Q. Yao, J. Yin, Y. Yokoe, N. P. Yu, A. F. Yuan, L. M. Zhai, C. P. Zhang, H. M. Zhang, J. L. Zhang, X. Zhang, X. Y. Zhang, Y. Zhang, Yi Zhang, Ying Zhang, S. P. Zhao, null Zhaxisangzhu, and X. X. Zhou
Subjects: Space and Planetary Science, Astronomy and Astrophysics
Abstract: HESS J1843–033 is a very high energy gamma-ray source whose origin remains unidentified. This work presents, for the first time, the energy spectrum of gamma rays beyond 100 TeV from the HESS J1843–033 region using the data recorded by the Tibet air shower array and its underground muon detector array. A gamma-ray source with an extension of 0.°34 ± 0.°12 is successfully detected above 25 TeV at (α, δ) = (281.°09 ± 0.°10, −3.°76 ± 0.°09) near HESS J1843–033 with a statistical significance of 6.2σ, and the source is named TASG J1844–038. The position of TASG J1844–038 is consistent with those of HESS J1843–033, eHWC J1842–035, and LHAASO J1843–0338. The measured gamma-ray energy spectrum in 25 TeV < E < 130 TeV is described with dN / dE = ( 9.70 ± 1.89 ) × 10 − 16 (E/40 TeV)−3.26±0.30 TeV−1 cm−2 s−1, and the spectral fit to the combined spectra of HESS J1843–033, LHAASO J1843–0338, and TASG J1844–038 implies the existence of a cutoff at 49.5 ± 9.0 TeV. Associations of TASG J1844–038 with SNR G28.6–0.1 and PSR J1844–0346 are also discussed in detail for the first time.
Published: 2022

34. First Detection of sub-PeV Diffuse Gamma Rays from the Galactic Disk: Evidence for Ubiquitous Galactic Cosmic Rays beyond PeV Energies

Author: Takashi Sako, X. R. Meng, X. L. Qian, Zhaoyang Feng, K. Kawata, Zicai Yang, L. Xue, Haibing Hu, Hong-peng Lu, Yu-Lei Chen, N. Tateyama, Harufumi Tsuchiya, Z. T. He, X. Y. Zhang, Minghui Liu, msub, W. J. Li, Y. Zhang, T. L. Chen, M. Amenomori, W. Y. Chen, A. Shiomi, K. Fang, M. Sakata, M. Shibata, Gui-Ming Le, H. M. Zhang, X. X. Zhou, Qi Gao, A. F. Yuan, M. Ohnishi, S. Ozawa, H. Sugimoto, Masaki Nishizawa, Y. H. Lin, Cirennima, S. Udo, mrow, T. Ohura, L. K. Ding, C. F. Feng, L. M. Zhai, Ang Li, X. J. Bi, Y. Ko, L. L. Jiang, Yongjun Bao, Y. Nakamura, Z. Y. Feng, H. B. Hu, H. Y. Jia, Masayoshi Kozai, Yang Guo, H. B. Jin, Jian Huang, Jia Zhang, Labaciren, Shoji Torii, Y. Q. Guo, Y. H. Tan, Zhaxisangzhu, Y. Yokoe, Huaguang Wang, H. J. Li, Donghong Chen, Y. Q. Lou, H. R. Wu, H. H. He, Shi-Ping Zhao, Q. B. Gou, Masato Takita, Chihiro Kato, K. Hibino, mrow> γ, Yi Zhang, J. Fang, C. X. Liu, J. S. Liu, Wenwei Liu, Y. Yamamoto, H. Nakada, H. Nanjo, Ying Zhang, S. W. Cui, X. B. Qu, B. Liu, W. Kihara, J. Shao, To. Saito, Danzengluobu, Katsuaki Kasahara, Y. Katayose, Xu Chen, Shigeaki Kato, Xiang Zhang, N. Hotta, Kazuoki Munakata, and W. Takano
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Astrophysics::High Energy Astrophysical Phenomena, Hadron, Gamma ray, FOS: Physical sciences, General Physics and Astronomy, Cosmic ray, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, Galaxy, Interstellar medium, 0103 physical sciences, High Energy Physics::Experiment, Disc, Astrophysics - High Energy Astrophysical Phenomena, 010306 general physics, Astrophysics::Galaxy Astrophysics
Abstract: We report, for the first time, the long-awaited detection of diffuse gamma rays with energies between 100 TeV and 1 PeV in the Galactic disk. Particularly, all gamma rays above 398 TeV are observed apart from known TeV gamma-ray sources and compatible with expectations from the hadronic emission scenario in which gamma rays originate from the decay of $\pi^0$'s produced through the interaction of protons with the interstellar medium in the Galaxy. This is strong evidence that cosmic rays are accelerated beyond PeV energies in our Galaxy and spread over the Galactic disk., Comment: Accepted for publication in the Physical Review Letters
Published: 2021

35. Gamma-Ray Observation of the Cygnus Region in the 100-TeV Energy Region

Author: Lihe Qian, H. H. He, Shi-Ping Zhao, Jia Zhang, J. Fang, Xi Liu, Yun-Hui Li, Donghong Chen, Y. Yamamoto, Q. Wu, J. S. Liu, mrow, H. M. Zhang, W. Takano, Wangdui, T. Ohura, X. X. Zhou, Takashi Sako, Ang Li, H. Sugimoto, L. K. Ding, H. Nakada, Z. Y. Feng, Huaguang Wang, Y. Yokoe, S. Ozawa, T. K. Sako, J. H. Yin, A. F. Yuan, H. Nanjo, N. P. Yu, X. L. Qian, Z. T. He, Kun Fang, Shoji Torii, C. C. Ning, M. Sakata, X. B. Qu, Peng Jiang, Y. H. Lin, T. L. Chen, X. R. Meng, Jian Huang, Gui-Ming Le, Y. P. Wang, Zhaxisangzhu, mrow> γ, Yu-Lei Chen, Yi Zhang, Zhaoyang Feng, Yongjun Bao, D. Kurashige, S. Okukawa, Chihiro Kato, L. Xue, Xiao-Feng Qian, Jun Xu, W. Y. Chen, Labaciren, Y. Q. Guo, H. B. Hu, Haibing Hu, Zicai Yang, Hong-peng Lu, N. Hotta, C. X. Liu, Wenwei Liu, H. J. Li, Y. Q. Lou, H. R. Wu, X. Y. Zhang, Minghui Liu, Masayoshi Kozai, msub, W. J. Li, Q. B. Gou, Y. Zhang, Masato Takita, A. Shiomi, M. Ohnishi, M. Shibata, N. Tateyama, Cirennima, Y. H. Tan, K. Kawata, S. Udo, M. Amenomori, H. B. Jin, Liyu Liu, Harufumi Tsuchiya, Masaki Nishizawa, Chuang Zhang, A. Gomi, C. F. Feng, Kazuoki Munakata, X. J. Bi, Ying Zhang, L. L. Jiang, S. W. Cui, Qi Gao, L. M. Zhai, Yang Guo, K. Hibino, B. Liu, Danzengluobu, Y. Q. Yao, J. Shao, H. Y. Jia, Y. Katayose, Shigeaki Kato, To. Saito, Katsuaki Kasahara, Xu Chen, Y. Nakazawa, Yoshimichi Nakamura, and Xiang Zhang
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Astrophysics::High Energy Astrophysical Phenomena, Gamma ray, FOS: Physical sciences, General Physics and Astronomy, Centroid, Astrophysics, Pulsar wind nebula, Galaxy, Particle acceleration, Pulsar, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics::Galaxy Astrophysics, Energy (signal processing)
Abstract: We report observations of gamma-ray emissions with energies in the 100 TeV energy region from the Cygnus region in our Galaxy. Two sources are significantly detected in the directions of the Cygnus OB1 and OB2 associations. Based on their positional coincidences, we associate one with a pulsar PSR J2032+4127 and the other mainly with a pulsar wind nebula PWN G75.2+0.1 with the pulsar moving away from its original birthplace situated around the centroid of the observed gamma-ray emission. This work would stimulate further studies of particle acceleration mechanisms at these gamma-ray sources., Accepted for publication in the Physical Review Letters
Published: 2021

36. Potential PeVatron supernova remnant G106.3+2.7 seen in the highest-energy gamma rays

Author: Yu-Lei Chen, Y. Yamamoto, N. Hotta, X. L. Qian, Hsiao-Chi Lu, Jian Huang, J. Shao, M. Shibata, H. Nakada, Masaki Nishizawa, X. J. Bi, M. Takita, Yi Zhang, Q. B. Gou, C. F. Feng, Y. Ko, L. Xue, Xu Chen, Yongjun Bao, J. S. Liu, L. L. Jiang, Kun Fang, Zicai Yang, Huaguang Wang, T. Ohura, Kazuoki Munakata, L. K. Ding, Haibing Hu, K. Kasahara, W. J. Li, Y. Yokoe, W. Takano, W. Kihara, Xuan Zhang, Labaciren, H. H. He, K. Kawata, Ying Zhang, Z. Y. Feng, B. Liu, Shi-Ping Zhao, W. Y. Chen, S. Ozawa, Jia Zhang, S. Torii, Y. Zhang, H. Nanjo, S. W. Cui, Takeshi Saito, J. Fang, A. Shiomi, Donghong Chen, Qi Gao, M. Amenomori, L. M. Zhai, Yang Guo, H. M. Zhang, X. X. Zhou, Z. T. He, H. Sugimoto, Danzengluobu, Y. H. Tan, Y. Q. Guo, T. L. Chen, Chihiro Kato, H. Y. Jia, H. J. Li, Y. Q. Lou, H. R. Wu, H. B. Jin, C. X. Liu, Wenwei Liu, M. Ohnishi, A. F. Yuan, Cirennima, S. Udo, Y. Katayose, Shigeaki Kato, Y. Nakamura, N. Tateyama, Harufumi Tsuchiya, M. Sakata, Gui-Ming Le, H. B. Hu, Masayoshi Kozai, Y. H. Lin, K. Hibino, Ang Li, X. B. Qu, X. R. Meng, Zhaoyang Feng, Zhaxisangzhu, T. K. Sako, X. Y. Zhang, and Minghui Liu
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Astrophysics::High Energy Astrophysical Phenomena, Gamma ray, FOS: Physical sciences, Astronomy and Astrophysics, Cosmic ray, Astrophysics, Electron, Synchrotron, law.invention, Particle acceleration, Pulsar, law, Atomic nucleus, Physics::Accelerator Physics, High Energy Physics::Experiment, Supernova remnant, Astrophysics - High Energy Astrophysical Phenomena
Abstract: Cosmic rays (protons and other atomic nuclei) are believed to gain energies of petaelectronvolts (PeV) and beyond at astrophysical particle accelerators called 'PeVatrons' inside our Galaxy. Although a characteristic feature of a PeVatron is expected to be a hard gamma-ray energy spectrum that extends beyond 100 teraelectronvolts (TeV) without a cutoff, none of the currently known sources exhibits such a spectrum due to the low maximum energy of accelerated cosmic rays or insufficient detector sensitivity around 100 TeV. Here we report the observation of gamma-ray emission from the supernova remnant G106.3+2.7 above 10 TeV. This work provides flux data points up to and above 100 TeV and indicates that the very-high-energy gamma-ray emission above 10 TeV is well correlated with a molecular cloud rather than the pulsar PSR J2229+6114. Regarding the gamma-ray emission mechanism of G106.3+2.7, this morphological feature appears to favor a hadronic origin via the {\pi}0 decay caused by accelerated relativistic protons over a leptonic one via the inverse-Compton scattering by relativistic electrons. Furthermore, we point out that an X-ray flux upper limit on the synchrotron spectrum would provide important information to firmly establish the hadronic scenario as the mechanism of particle acceleration at the source., Comment: Published in Nature Astronomy
Published: 2021
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37. Measurement of the Iron Spectrum in Cosmic Rays from 10 GeV$/n$ to 2.0 TeV$/n$ with the Calorimetric Electron Telescope on the International Space Station

Author: O, Adriani, Y, Akaike, K, Asano, Y, Asaoka, E, Berti, G, Bigongiari, W R, Binns, M, Bongi, P, Brogi, A, Bruno, J H, Buckley, N, Cannady, G, Castellini, C, Checchia, M L, Cherry, G, Collazuol, K, Ebisawa, H, Fuke, S, Gonzi, T G, Guzik, T, Hams, K, Hibino, M, Ichimura, K, Ioka, W, Ishizaki, M H, Israel, K, Kasahara, J, Kataoka, R, Kataoka, Y, Katayose, C, Kato, N, Kawanaka, Y, Kawakubo, K, Kobayashi, K, Kohri, H S, Krawczynski, J F, Krizmanic, J, Link, P, Maestro, P S, Marrocchesi, A M, Messineo, J W, Mitchell, S, Miyake, A A, Moiseev, M, Mori, N, Mori, H M, Motz, K, Munakata, S, Nakahira, J, Nishimura, G A, de Nolfo, S, Okuno, J F, Ormes, N, Ospina, S, Ozawa, L, Pacini, P, Papini, B F, Rauch, S B, Ricciarini, K, Sakai, T, Sakamoto, M, Sasaki, Y, Shimizu, A, Shiomi, P, Spillantini, F, Stolzi, S, Sugita, A, Sulaj, M, Takita, T, Tamura, T, Terasawa, S, Torii, Y, Tsunesada, Y, Uchihori, E, Vannuccini, J P, Wefel, K, Yamaoka, S, Yanagita, A, Yoshida, and K, Yoshida
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Astrophysics::High Energy Astrophysical Phenomena, Cosmic ray acceleration Cosmic ray composition and spectra Cosmic ray propagation Cosmic ray sources Cosmic rays and astroparticles, FOS: Physical sciences, Astrophysics - High Energy Astrophysical Phenomena, Cosmic rays
Abstract: The Calorimetric Electron Telescope (CALET), in operation on the International Space Station since 2015, collected a large sample of cosmic-ray iron over a wide energy interval. In this Letter a measurement of the iron spectrum is presented in the range of kinetic energy per nucleon from 10 GeV$/n$ to 2.0 TeV$/n$ allowing the inclusion of iron in the list of elements studied with unprecedented precision by space-borne instruments. The measurement is based on observations carried out from January 2016 to May 2020. The CALET instrument can identify individual nuclear species via a measurement of their electric charge with a dynamic range extending far beyond iron (up to atomic number $Z$ = 40). The energy is measured by a homogeneous calorimeter with a total equivalent thickness of 1.2 proton interaction lengths preceded by a thin (3 radiation lengths) imaging section providing tracking and energy sampling. The analysis of the data and the detailed assessment of systematic uncertainties are described and results are compared with the findings of previous experiments. The observed differential spectrum is consistent within the errors with previous experiments. In the region from 50 GeV$/n$ to 2 TeV$/n$ our present data are compatible with a single power law with spectral index -2.60 $\pm$ 0.03., Comment: main text: 7 pages, 4 figures; supplemental material: 10 pages, 12 figures, 1 table. arXiv admin note: text overlap with arXiv:2012.10319
Published: 2021
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38. Observation of Variations in Cosmic Ray Single Count Rates During Thunderstorms and Implications for Large-Scale Electric Field Changes

Author: R. U. Abbasi, T. Abu-Zayyad, M. Allen, Y. Arai, R. Arimura, E. Barcikowski, J. W. Belz, D. R. Bergman, S. A. Blake, I. Buckland, R. Cady, B. G. Cheon, J. Chiba, M. Chikawa, T. Fujii, K. Fujisue, K. Fujita, R. Fujiwara, M. Fukushima, R. Fukushima, G. Furlich, N. Globus, R. Gonzalez, W. Hanlon, M. Hayashi, N. Hayashida, K. Hibino, R. Higuchi, K. Honda, N. Husseini, D. Ikeda, T. Inadomi, N. Inoue, T. Ishii, H. Ito, D. Ivanov, H. Iwakura, A. Iwasaki, H. M. Jeong, S. Jeong, H. Johnson, C. C. H. Jui, K. Kadota, F. Kakimoto, O. Kalashev, K. Kasahara, S. Kasami, H. Kawai, S. Kawakami, S. Kawana, K. Kawata, I. Kharuk, E. Kido, H. B. Kim, J. H. Kim, M. H. Kim, S. W. Kim, Y. Kimura, S. Kishigami, Y. Kubota, S. Kurisu, V. Kuzmin, M. Kuznetsov, Y. J. Kwon, K. H. Lee, R. LeVon, B. Lubsandorzhiev, J. P. Lundquist, K. Machida, H. Matsumiya, T. Matsuyama, J. N. Matthews, R. Mayta, J. Mazich, M. Minamino, K. Mukai, I. Myers, P. Myers, S. Nagataki, K. Nakai, R. Nakamura, T. Nakamura, Y. Nakamura, A. Nakazawa, E. Nishio, T. Nonaka, K. O’Brien, H. Oda, S. Ogio, M. Ohnishi, H. Ohoka, Y. Oku, T. Okuda, Y. Omura, M. Ono, R. Onogi, A. Oshima, S. Ozawa, I. H. Park, M. Potts, M. S. Pshirkov, J. Remington, D. C. Rodriguez, G. I. Rubtsov, D. Ryu, H. Sagawa, R. Sahara, Y. Saito, N. Sakaki, T. Sako, N. Sakurai, K. Sano, K. Sato, T. Seki, K. Sekino, P. D. Shah, Y. Shibasaki, F. Shibata, N. Shibata, T. Shibata, H. Shimodaira, B. K. Shin, H. S. Shin, D. Shinto, J. D. Smith, P. Sokolsky, N. Sone, B. T. Stokes, T. A. Stroman, Y. Takagi, Y. Takahashi, M. Takamura, M. Takeda, R. Takeishi, A. Taketa, M. Takita, Y. Tameda, H. Tanaka, K. Tanaka, M. Tanaka, Y. Tanoue, S. B. Thomas, G. B. Thomson, P. Tinyakov, I. Tkachev, H. Tokuno, T. Tomida, S. Troitsky, R. Tsuda, Y. Tsunesada, Y. Uchihori, S. Udo, T. Uehama, F. Urban, T. Wong, M. Yamamoto, K. Yamazaki, J. Yang, K. Yashiro, F. Yoshida, Y. Yoshioka, Y. Zhezher, and Z. Zundel
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics - Atmospheric and Oceanic Physics, High Energy Physics - Experiment (hep-ex), Astrophysics::High Energy Astrophysical Phenomena, Atmospheric and Oceanic Physics (physics.ao-ph), FOS: Physical sciences, Astrophysics - High Energy Astrophysical Phenomena, High Energy Physics - Experiment
Abstract: We present the first observation by the Telescope Array Surface Detector (TASD) of the effect of thunderstorms on the development of cosmic ray single count rate intensity over a 700 km$^{2}$ area. Observations of variations in the secondary low-energy cosmic ray counting rate, using the TASD, allow us to study the electric field inside thunderstorms, on a large scale, as it progresses on top of the 700 km$^{2}$ detector, without dealing with the limitation of narrow exposure in time and space using balloons and aircraft detectors. In this work, variations in the cosmic ray intensity (single count rate) using the TASD, were studied and found to be on average at the $\sim(0.5-1)\%$ and up to 2\% level. These observations were found to be both in excess and in deficit. They were also found to be correlated with lightning in addition to thunderstorms. These variations lasted for tens of minutes; their footprint on the ground ranged from 6 to 24 km in diameter and moved in the same direction as the thunderstorm. With the use of simple electric field models inside the cloud and between cloud to ground, the observed variations in the cosmic ray single count rate were recreated using CORSIKA simulations. Depending on the electric field model used and the direction of the electric field in that model, the electric field magnitude that reproduces the observed low-energy cosmic ray single count rate variations was found to be approximately between 0.2-0.4 GV. This in turn allows us to get a reasonable insight on the electric field and its effect on cosmic ray air showers inside thunderstorms.
Published: 2021
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39. Direct Measurement of the Cosmic-Ray Carbon and Oxygen Spectra from 10 GeV/n to 2.2 TeV/n with the Calorimetric Electron Telescope on the International Space Station

Author: Toshio Terasawa, Satoshi Sugita, L. Pacini, Ryuho Kataoka, W. Ishizaki, N. Mori, Y. Uchihori, Alberto Messineo, K. Ebisawa, N. Ospina, H. Fuke, Katsuaki Asano, P. Spillantini, Michael Cherry, Yosui Akaike, Norita Kawanaka, Masaki Mori, R. Sparvoli, Shoji Torii, F. Palma, T. Hams, S. B. Ricciarini, Maria Grazia Bagliesi, Chihiro Kato, P. Papini, E. Vannuccini, A. Bruno, T. Sakamoto, Sandro Gonzi, M. H. Israel, T. Tamura, J. E. Suh, Kazunori Kohri, J. Link, Holger Motz, P. Brogi, Masato Takita, O. Adriani, Kazutaka Yamaoka, Kunihito Ioka, Jun Kataoka, P. Maestro, P. S. Marrocchesi, A. A. Moiseev, Jun Nishimura, Y. Katayose, John F. Krizmanic, A. Sulaj, G. Castellini, Henric Krawczynski, G. Bigongiari, Shohei Yanagita, Y. Shimizu, Satoshi Nakahira, Y. Tsunesada, Kenji Yoshida, M. Bongi, T. G. Guzik, Eugenio Berti, A. Yoshida, W. R. Binns, G. Collazuol, Brian Rauch, J. P. Wefel, J. H. Buckley, G. A. de Nolfo, S. Miyake, M. Ichimura, N. Cannady, S. Ozawa, S. Okuno, C. Checchia, John Mitchell, Kazuoki Munakata, A. Shiomi, Yoichi Asaoka, F. Stolzi, K. Hibino, Y. Kawakubo, M. Sasaki, Katsuaki Kasahara, K. Sakai, K. Kobayashi, and J. F. Ormes
Subjects: Physics, Spectral index, Spectrometer, Astrophysics::High Energy Astrophysical Phenomena, General Physics and Astronomy, Cosmic ray, Electron, Kinetic energy, 7. Clean energy, 01 natural sciences, Spectral line, law.invention, Nuclear physics, Telescope, law, 0103 physical sciences, 010306 general physics, Nucleon
Abstract: In this paper, we present the measurement of the energy spectra of carbon and oxygen in cosmic rays based on observations with the Calorimetric Electron Telescope (CALET) on the International Space Station from October 2015 to October 2019. Analysis, including the detailed assessment of systematic uncertainties, and results are reported. The energy spectra are measured in kinetic energy per nucleon from 10 GeV$/n$ to 2.2 TeV$/n$ with an all-calorimetric instrument with a total thickness corresponding to 1.3 nuclear interaction length. The observed carbon and oxygen fluxes show a spectral index change of $\sim$0.15 around 200 GeV$/n$ established with a significance $>3\sigma$. They have the same energy dependence with a constant C/O flux ratio $0.911\pm 0.006$ above 25 GeV$/n$. The spectral hardening is consistent with that measured by AMS-02, but the absolute normalization of the flux is about 27% lower, though in agreement with observations from previous experiments including the PAMELA spectrometer and the calorimetric balloon-borne experiment CREAM.
Published: 2020

40. Observations of the Origin of Downward Terrestrial Gamma‐Ray Flashes

Author: Hideaki Shimodaira, Hyoming Jeong, Hidemi Ito, N. Inoue, Takashi Sako, D. Ikeda, M. Ohnishi, Taichi Inadomi, Tareq Abu-Zayyad, Takayuki Tomida, Toru Nakamura, Federico R. Urban, Yuya Oku, Oleg Kalashev, Fumiya Shibata, Kenichi Kadota, S. Udo, C. C. H. Jui, Pierre Sokolsky, M. Takeda, Zach Zundel, Shigehiro Nagataki, Sergey Troitsky, Toshiyuki Nonaka, M. Byrne, Kengo Sano, R. Sahara, Matt Potts, K. H. Lee, Yasunori Saito, Hiroyuki Sagawa, Ben Stokes, T.-A. Shibata, Heungsu Shin, S. B. Thomas, H. Tokuno, H. Yamaoka, Yuta Tanoue, Motoki Hayashi, J. P. Lundquist, Gordon Thomson, Tom Stroman, Robert Cady, Kiyoshi Tanaka, Michiyuki Chikawa, J. Remington, Y. Hayashi, G. Furlich, Takaaki Ishii, Igor Tkachev, Naohiro Sone, Y. Zhezher, Yoshihiko Nakamura, Akimichi Taketa, J. D. Smith, T. Fujii, Keitaro Fujita, Y. J. Kwon, Hideyuki Ohoka, Vladim Kuzmin, H. Oda, K. Kawata, D. C. Rodriguez, S. Ozawa, BayarJon Paul Lubsandorzhiev, S. Jeong, B. K. Shin, D. Rodeheffer, Naoaki Hayashida, B. G. Cheon, T. Matuyama, Kenta Yashiro, Mayuko Minamino, M. Allen, Tiffany Wong, R. Takeishi, Yuichiro Tameda, Isaac Myers, K. Honda, Ryota Fujiwara, John N. Matthews, John Belz, Elliott Barcikowski, K. Kasahara, Masaki Fukushima, Akitoshi Oshima, Fumio Kakimoto, Dmitri Ivanov, Naoto Sakaki, Paul R. Krehbiel, M. Yamamoto, Y. Takahashi, Keijiro Mukai, Masaomi Ono, Masato Takita, M. Wallace, K. Yamazaki, H. Kawai, Masaaki Tanaka, Nobuyuki Sakurai, S. Kawakami, Hiroyuki Matsumiya, Saori Kasami, A. Di Matteo, T. Seki, Takafumi Uehama, Y. Tsunesada, Maxim Pshirkov, R. Mayta, R. LeVon, Hongsu Kim, Y. Uchihori, Eiji Kido, Kei Nakai, M. V. Kuznetsov, Kazuhiro Machida, K. Sekino, William Hanlon, T. Okuda, Inkyu Park, Grigory Rubtsov, William Rison, D. R. Bergman, R. U. Abbasi, Peter Tinyakov, Samuel Blake, Shoichi Ogio, J. H. Kim, Y. Omura, Dongsu Ryu, Mark A. Stanley, Hirokazu Iwakura, Y. Takagi, Ryo Nakamura, Kazuo Saito, H. Yoshii, M. Yosei, and K. Hibino
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Atmospheric Science, 010504 meteorology & atmospheric sciences, Conjunction (astronomy), Gamma ray, FOS: Physical sciences, Astrophysics, Electron, Radio atmospheric, 01 natural sciences, Lightning, High Energy Physics - Experiment, Physics - Atmospheric and Oceanic Physics, High Energy Physics - Experiment (hep-ex), Geophysics, Space and Planetary Science, Electric field, Atmospheric and Oceanic Physics (physics.ao-ph), Earth and Planetary Sciences (miscellaneous), Atmospheric electricity, Astrophysics - High Energy Astrophysical Phenomena, Cosmic-ray observatory, 0105 earth and related environmental sciences
Abstract: In this paper we report the first close, high-resolution observations of downward-directed terrestrial gamma-ray flashes (TGFs) detected by the large-area Telescope Array cosmic ray observatory, obtained in conjunction with broadband VHF interferometer and fast electric field change measurements of the parent discharge. The results show that the TGFs occur during strong initial breakdown pulses (IBPs) in the first few milliseconds of negative cloud-to-ground and low-altitude intracloud flashes, and that the IBPs are produced by a newly-identified streamer-based discharge process called fast negative breakdown. The observations indicate the relativistic runaway electron avalanches (RREAs) responsible for producing the TGFs are initiated by embedded spark-like transient conducting events (TCEs) within the fast streamer system, and potentially also by individual fast streamers themselves. The TCEs are inferred to be the cause of impulsive sub-pulses that are characteristic features of classic IBP sferics. Additional development of the avalanches would be facilitated by the enhanced electric field ahead of the advancing front of the fast negative breakdown. In addition to showing the nature of IBPs and their enigmatic sub-pulses, the observations also provide a possible explanation for the unsolved question of how the streamer to leader transition occurs during the initial negative breakdown, namely as a result of strong currents flowing in the final stage of successive IBPs, extending backward through both the IBP itself and the negative streamer breakdown preceding the IBP., Comment: Typo fixed and reference added. Manuscript is 36 pages. Supplemental Information is 42 pages. This paper is to be published in the Journal of Geophysical Research: Atmospheres. Online data repository: Open Science Framework DOI: 10.17605/OSF.IO/Z3XDA
Published: 2020

41. Search for Large-scale Anisotropy on Arrival Directions of Ultra-high-energy Cosmic Rays Observed with the Telescope Array Experiment

Author: Takashi Sako, Hideaki Shimodaira, Hyoming Jeong, Ryo Higuchi, Inkyu Park, Kenta Yashiro, R. U. Abbasi, Tareq Abu-Zayyad, R. Azuma, Fumiya Shibata, F. Kakimoto, R. Ishimori, Daisuke Ikeda, K. Yamazaki, H. Kawai, Tiffany Wong, R. Takeishi, Masaki Fukushima, Maxim Pshirkov, Hongsu Kim, B. K. Shin, Hideki Tanaka, Toshiyuki Fujii, B. G. Cheon, T. Seki, John Belz, K. Kawata, BayarJon Paul Lubsandorzhiev, Akimichi Taketa, Min Hyo Kim, G. Furlich, Takaaki Ishii, Mayuko Minamino, K. Honda, Takayuki Tomida, Seok Ho Jeong, K. H. Lee, Yuta Tanoue, Masaaki Tanaka, D. C. Rodriguez, T.-A. Shibata, S. Kawakami, Motoki Hayashi, Zach Zundel, Peter Tinyakov, Samuel Blake, Gordon Thomson, Ben Stokes, Tom Stroman, Robert Cady, J. P. Lundquist, Shoichi Ogio, Kozo Fujisue, Hiroyuki Sagawa, M. Yamamoto, M. Yosei, Hidemi Ito, Grigory Rubtsov, Koichi Sekino, Kiyoshi Tanaka, D. R. Bergman, T. Suzawa, Y. Zhezher, Heungsu Shin, Isaac Myers, Katsuaki Kasahara, Y. Takahashi, Mai Takamura, Nobuyuki Sakurai, Yuya Oku, Oleg Kalashev, K. Hibino, Shoichi Kishigami, M. Allen, Sergey Troitsky, Toru Nakamura, Kenichi Kadota, T. Matsuyama, S. Ozawa, Masaomi Ono, Toshiyuki Nonaka, Y. Uchihori, Kei Nakai, Ryota Onogi, A. Di Matteo, J. Remington, Hideyuki Ohoka, R. Mayta, Vladim Kuzmin, Ryota Fujiwara, Keitaro Fujita, Saori Kasami, Shingo Kawana, Naoto Sakaki, Naoaki Hayashida, Yoshihiko Nakamura, William Hanlon, Priti Shah, T. Okuda, J. Yang, Masato Takita, R. Sahara, Pierre Sokolsky, M. Takeda, Shigehiro Nagataki, M. Abe, Akitoshi Oshima, Y. Tsunesada, H. Tokuno, Younghoon Kwon, J. D. Smith, J. H. Kim, Elliott Barcikowski, Dmitri Ivanov, Keijiro Mukai, Jyunsei Chiba, Dongsu Ryu, Hirokazu Iwakura, Y. Takagi, Kohei Yada, Y. Omura, Igor Tkachev, Naohiro Sone, H. Oda, N. Inoue, M. Ohnishi, Taichi Inadomi, Federico R. Urban, S. Udo, C. C. H. Jui, Kengo Sano, S. B. Thomas, Yasunori Saito, Yuichiro Tameda, John N. Matthews, S. W. Kim, Hiroyuki Matsumiya, M. Chikawa, Takafumi Uehama, Eiji Kido, M. V. Kuznetsov, Kazuhiro Machida, and Ryo Nakamura
Subjects: Physics, Pierre Auger Observatory, High Energy Astrophysical Phenomena (astro-ph.HE), 010504 meteorology & atmospheric sciences, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy and Astrophysics, Cosmic ray, 01 natural sciences, Auger, Computational physics, law.invention, Telescope, Dipole, Amplitude, Space and Planetary Science, law, 0103 physical sciences, Ultra-high-energy cosmic ray, Astrophysics - High Energy Astrophysical Phenomena, Anisotropy, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract: Motivated by the detection of a significant dipole structure in the arrival directions of ultrahigh-energy cosmic rays above 8 EeV reported by the Pierre Auger Observatory (Auger), we search for a large-scale anisotropy using data collected with the surface detector array of the Telescope Array Experiment (TA). With 11 years of TA data, a dipole structure in a projection of the right ascension is fitted with an amplitude of 3.3+- 1.9% and a phase of 131 +- 33 degrees. The corresponding 99% confidence-level upper limit on the amplitude is 7.3%. At the current level of statistics, the fitted result is compatible with both an isotropic distribution and the dipole structure reported by Auger., Comment: 6 pages, 3 figures, 1 table, Proofed title. Added journal reference and DOI
Published: 2020
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42. Gamma Ray Showers Observed at Ground Level in Coincidence With Downward Lightning Leaders

Author: Fumiya Shibata, R. W. Springer, Maxim Pshirkov, John Belz, Akitoshi Oshima, Hiroyuki Sagawa, Fumio Kakimoto, D. R. Bergman, Zach Zundel, K. Hibino, Koichi Sekino, K. Kasahara, Y. Tsunesada, Hideaki Shimodaira, Ryo Nakamura, R. LeVon, Hongsu Kim, Kazuo Saito, Shoichi Kishigami, Heungsu Shin, Shunsuke Ozawa, Mayuko Minamino, K. Honda, Hidemi Ito, K. Martens, Toshitsugu Fujii, M. Yamamoto, Y. Yoneda, N. Inoue, G. Vasiloff, Ryuji Takeishi, Masato Takita, Nobuyuki Sakurai, Masaomi Ono, Priti Shah, Hideki Tanaka, Grigory Rubtsov, M. Ohnishi, H. Yoshii, Ryota Onogi, Ben Stokes, Daisuke Ikeda, Elliott Barcikowski, Sergey Troitsky, Masaaki Tanaka, T. Matuyama, Vladim Kuzmin, Jyunsei Chiba, Dongsu Ryu, M. Allen, Helio Takai, Takayuki Tomida, Dmitri Ivanov, Tiffany Wong, B. G. Cheon, Keijiro Mukai, S. Jeong, Masaki Fukushima, B. K. Shin, K. Oki, Federico R. Urban, J. Remington, S. Udo, C. C. H. Jui, Tareq Abu-Zayyad, R. Yamane, Peter Tinyakov, Samuel Blake, Shoichi Ogio, Rasha Abbasi, William Rison, H. Kawai, Michiyuki Chikawa, M. Byrne, Naoaki Hayashida, S. Kawakami, Kiyoshi Tanaka, S. B. Thomas, Akimichi Taketa, Y. Hayashi, Toru Nakamura, K. Kawata, T. Seki, Kenichi Kadota, J. Lan, Igor Tkachev, R. Cady, J. P. Lundquist, G. Furlich, Takaaki Ishii, D. Rodeheffer, Toshiyuki Nonaka, T.-A. Shibata, Gordon Thomson, S. Yoshida, Hiroshi Yamaoka, Tom Stroman, Naoto Sakaki, Kenta Yashiro, D. C. Rodriguez, Isaac Myers, Inkyu Park, Y. Uchihori, H. Tokuno, K. Yamazaki, J. D. Smith, Yuichiro Tameda, John N. Matthews, William Hanlon, T. Okuda, J. H. Kim, J. Yang, Y. J. Kwon, Hideyuki Ohoka, Paul R. Krehbiel, T. Goto, Eiji Kido, Pierre Sokolsky, Kazuhiro Machida, M. Takeda, Shigehiro Nagataki, R. J. Thomas, and O. Kalashev
Subjects: Atmospheric Science, 010504 meteorology & atmospheric sciences, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, Radiation, 01 natural sciences, High Energy Physics - Experiment, law.invention, Telescope, High Energy Physics - Experiment (hep-ex), Electron avalanche, law, 0103 physical sciences, Earth and Planetary Sciences (miscellaneous), Cosmic-ray observatory, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Lightning detection, Astrophysics::Instrumentation and Methods for Astrophysics, Gamma ray, Lightning, Physics - Atmospheric and Oceanic Physics, Geophysics, 13. Climate action, Space and Planetary Science, Atmospheric and Oceanic Physics (physics.ao-ph), Satellite, Astrophysics - High Energy Astrophysical Phenomena
Abstract: Bursts of gamma ray showers have been observed in coincidence with downward propagating negative leaders in lightning flashes by the Telescope Array Surface Detector (TASD). The TASD is a 700~square kilometer cosmic ray observatory located in southwestern Utah, U.S.A. In data collected between 2014 and 2016, correlated observations showing the structure and temporal development of three shower-producing flashes were obtained with a 3D lightning mapping array, and electric field change measurements were obtained for an additional seven flashes, in both cases co-located with the TASD. National Lightning Detection Network (NLDN) information was also used throughout. The showers arrived in a sequence of 2--5 short-duration ($\le$10~$\mu$s) bursts over time intervals of several hundred microseconds, and originated at an altitude of $\simeq$3--5 kilometers above ground level during the first 1--2 ms of downward negative leader breakdown at the beginning of cloud-to-ground lightning flashes. The shower footprints, associated waveforms and the effect of atmospheric propagation indicate that the showers consist primarily of downward-beamed gamma radiation. This has been supported by GEANT simulation studies, which indicate primary source fluxes of $\simeq$$10^{12}$--$10^{14}$ photons for $16^{\circ}$ half-angle beams. We conclude that the showers are terrestrial gamma-ray flashes (TGFs), similar to those observed by satellites, but that the ground-based observations are more representative of the temporal source activity and are also more sensitive than satellite observations, which detect only the most powerful TGFs.
Published: 2018

43. The bursts of high energy events observed by the telescope array surface detector

Author: Hiroshi Yamaoka, T. Suzawa, Robert M. Anderson, Hideaki Shimodaira, Isaac Myers, M. Abe, Kenta Yashiro, T. Goto, Elliott Barcikowski, Dmitri Ivanov, Keijiro Mukai, Maxim Pshirkov, Sergey Troitsky, A. L. Sampson, Takaaki Ishii, Kanako Yamazaki, Priti Shah, K. Tsutsumi, S. Kitamura, Fumiya Shibata, D. C. Rodriguez, Hidemi Ito, S. Kawakami, J. P. Lundquist, Keiji Saito, Igor Tkachev, R. Ishimori, John Belz, R. W. Springer, Pierre Sokolsky, Naoaki Hayashida, Akimichi Taketa, Ben Stokes, K. Oki, Koichi Sekino, H. Yoshii, Tareq Abu-Zayyad, R. Yamane, Federico R. Urban, Kiyoshi Tanaka, Y. Yoneda, N. Inoue, M. Ohnishi, Michiyuki Chikawa, Hiroyuki Sagawa, R. Zollinger, S. Udo, C. C. H. Jui, Heungsu Shin, M. Takeda, Shigehiro Nagataki, Ryuji Takeishi, Akitoshi Oshima, Y. Uchihori, Y. J. Kwon, Hideyuki Ohoka, K. Nagasawa, S. B. Thomas, Tomohiro Matsuda, H. Kawai, Mai Takamura, T.-A. Shibata, Fumio Kakimoto, Peter Tinyakov, Gordon Thomson, K. Hibino, Samuel Blake, Byung Gu Cheon, Tom Stroman, Robert Cady, Shoichi Ogio, Zach Zundel, Hang Bae Kim, G. Vasiloff, L. M. Scott, J. Ogura, K. Martens, Hideki Tanaka, Jyunsei Chiba, Dongsu Ryu, B. K. Shin, Takayuki Tomida, Masato Takita, Mayuko Minamino, K. Honda, Yasunori Kitamura, Rasha Abbasi, A. Nozato, Y. Hayashi, Yoshiki Tsunesada, Daisuke Ikeda, M. Allen, Inkyu Park, S. R. Stratton, K. Kawata, Masaaki Tanaka, Nobuyuki Sakurai, Tiffany Wong, Masaki Fukushima, Douglas Bergman, Takahiro Fujii, V. Kuzmin, Ryota Onogi, J. H. Kim, S. Yoshida, Naoto Sakaki, O. Kalashev, Toru Nakamura, Eiji Kido, Kazuhiro Machida, Kenichi Kadota, T. Matsuyama, S. Ozawa, Yasunori Saito, K. Kasahara, Shoichi Kishigami, R. Azuma, Yuichiro Tameda, John N. Matthews, Masaomi Ono, G. Rubtsov, Shingo Kawana, William Hanlon, T. Okuda, J. Yang, H. Tokuno, J. D. Smith, J. Lan, and Toshiyuki Nonaka
Subjects: Physics, 010504 meteorology & atmospheric sciences, Gamma ray, General Physics and Astronomy, Astronomy, Cosmic ray, Astrophysics, 01 natural sciences, Lightning, Particle detector, law.invention, Telescope, Air shower, law, 0103 physical sciences, Ultra-high-energy cosmic ray, 010306 general physics, 0105 earth and related environmental sciences, Terrestrial gamma-ray flash
Abstract: The Telescope Array (TA) experiment is designed to detect air showers induced by ultra high energy cosmic rays. The TA ground Surface particle Detector (TASD) observed several short-time bursts of air shower like events. These bursts are not likely due to chance coincidence between single shower events. The expectation of chance coincidence is less than 10 − 4 for five-year's observation. We checked the correlation between these bursts of events and lightning data, and found evidence for correlations in timing and position. Some features of the burst events are similar to those of a normal cosmic ray air shower, and some are not. On this paper, we report the observed bursts of air shower like events and their correlation with lightning.
Published: 2017

44. First upper limits on the radar cross section of cosmic-ray induced extensive air showers

Author: John Belz, Eiji Kido, Nobuyuki Sakurai, Fumiya Shibata, Kazuhiro Machida, R. Ishimori, Takahiro Fujii, Helio Takai, M. Abou Bakr Othman, Maxim Pshirkov, J. H. Kim, W. R. Cho, C. Jayanthmurthy, O. Kalashev, R. W. Springer, Peter Tinyakov, Samuel Blake, Shoichi Ogio, Charlie Jui, Mayuko Minamino, K. Honda, Yasunori Kitamura, Masaaki Tanaka, G. Vasiloff, J. P. Lundquist, Toru Nakamura, Jyunsei Chiba, Kenichi Kadota, Akitoshi Oshima, Dongsu Ryu, Ryuji Takeishi, M. J. Chae, S. Kitamura, Hidemi Ito, K. Nagasawa, Y. Uchihori, Hideaki Shimodaira, Hiroyuki Sagawa, Fumio Kakimoto, T. Matsuyama, D. Z. Besson, M. Allen, Y. J. Kwon, Michiyuki Chikawa, Priti Shah, T. Suzawa, Hideyuki Ohoka, Isaac Myers, K. Oki, Y. Yoneda, N. Inoue, S. I. Lim, M. Ohnishi, Tomohiro Matsuda, S. Prohira, Masato Takita, Suresh Venkatesh, K. Yamazaki, J. Ogura, Mai Takamura, Tareq Abu-Zayyad, R. Yamane, Ahmad RezazadehReyhani, Toshiyuki Nonaka, T. Goto, S. Udo, R. Azuma, Rasha Abbasi, Hiroshi Yamaoka, Pierre Sokolsky, Yuichiro Tameda, B. G. Cheon, John N. Matthews, L. M. Scott, Zach Zundel, Behrouz Farhang-Boroujeny, Takaaki Ishii, Bokkyun Shin, A. Nozato, Y. Hayashi, Sergey Troitsky, Hongsu Kim, A. L. Sampson, K. Kawata, D. C. Rodriguez, V. Kuzmin, S. Kawakami, Akimichi Taketa, K. Martens, H. Kawai, S. Yoshida, Hideki Tanaka, M. Takeda, Daisuke Ikeda, M. Byrne, S. B. Thomas, S. R. Stratton, Shigehiro Nagataki, Tiffany Wong, Masaki Fukushima, J. Lan, Douglas Bergman, Ross Anderson, Kiyoshi Tanaka, Kenta Yashiro, K. Tsutsumi, R. Zollinger, Naoaki Hayashida, M. Abe, S. Kunwar, Igor Tkachev, R. Cady, David Schurig, K. Hibino, H. Yoshii, Y. Tsunesada, Shunsuke Ozawa, Ben Stokes, Elliott Barcikowski, Dmitri Ivanov, Keijiro Mukai, Federico R. Urban, T.-A. Shibata, Gordon Thomson, Tom Stroman, Inkyu Park, K. Kasahara, Masaomi Ono, G. Rubtsov, Takayuki Tomida, W.H. Gillman, H. Tokuno, J. D. Smith, Shingo Kawana, William Hanlon, T. Okuda, J. Yang, and J. C. Hanson
Subjects: Physics, Radar cross-section, Physics::Instrumentation and Detectors, Pulse-Doppler radar, business.industry, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astronomy and Astrophysics, 01 natural sciences, law.invention, Continuous-wave radar, Radar engineering details, Optics, Radar astronomy, law, Radar imaging, 0103 physical sciences, Radar, Radar display, Astrophysics - Instrumentation and Methods for Astrophysics, 010306 general physics, business, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, Remote sensing
Abstract: TARA (Telescope Array Radar) is a cosmic ray radar detection experiment colocated with Telescope Array, the conventional surface scintillation detector (SD) and fluorescence telescope detector (FD) near Delta, Utah, U.S.A. The TARA detector combines a 40 kW, 54.1 MHz VHF transmitter and high-gain transmitting antenna which broadcasts the radar carrier over the SD array and within the FD field of view, towards a 250 MS/s DAQ receiver. TARA has been collecting data since 2013 with the primary goal of observing the radar signatures of extensive air showers (EAS). Simulations indicate that echoes are expected to be short in duration (~10 microseconds) and exhibit rapidly changing frequency, with rates on the order of 1 MHz/microsecond. The EAS radar cross-section (RCS) is currently unknown although it is the subject of over 70 years of speculation. A novel signal search technique is described in which the expected radar echo of a particular air shower is used as a matched filter template and compared to waveforms obtained by triggering the radar DAQ using the Telescope Array fluorescence detector. No evidence for the scattering of radio frequency radiation by EAS is obtained to date. We report the first quantitative RCS upper limits using EAS that triggered the Telescope Array Fluorescence Detector., Comment: 21 pages, 30 figures
Published: 2017

45. Search for EeV protons of galactic origin

Author: R. Ishimori, R. Zollinger, Kenta Yashiro, Yasunori Saito, Yuichiro Tameda, John N. Matthews, K. Nagasawa, J. Yang, Y. J. Kwon, Eiji Kido, Hideyuki Ohoka, Kazuhiro Machida, J. Lan, S. Kitamura, Masato Takita, M. Abe, Byung Gu Cheon, Hidemi Ito, John Belz, Toshiyuki Nonaka, Elliott Barcikowski, Takayuki Tomida, Igor Tkachev, R. Cady, Motoki Hayashi, J. P. Lundquist, Ryuji Takeishi, BayarJon Paul Lubsandorzhiev, K. Hibino, Ben Stokes, Inkyu Park, T. Matsuyama, L. M. Scott, S. Ozawa, Dmitri Ivanov, Keijiro Mukai, Hiroshi Yamaoka, Tomohiro Matsuda, Mayuko Minamino, K. Honda, Y. Yoneda, N. Inoue, Federico R. Urban, A. Nozato, Y. Hayashi, K. Oki, M. Ohnishi, Yasunori Kitamura, T. Goto, S. Udo, C. C. H. Jui, K. Kawata, M. Allen, Douglas Bergman, Yoshiki Tsunesada, Nobuyuki Sakurai, Masaaki Tanaka, Sergey Troitsky, Daisuke Ikeda, Hideaki Shimodaira, Toru Nakamura, Kenichi Kadota, S. R. Stratton, H. Kawai, K. Kasahara, Akitoshi Oshima, S. B. Thomas, O. Kalashev, Shoichi Kishigami, Koichi Sekino, Kanako Yamazaki, Takahiro Fujii, Tiffany Wong, Priti Shah, K. Saito, Masaki Fukushima, Masaomi Ono, Jyunsei Chiba, Dongsu Ryu, B. K. Shin, Grigory Rubtsov, K. Martens, Hideki Tanaka, S. Yoshida, Y. Takahashi, Mai Takamura, Ryota Onogi, J. H. Kim, Vladim Kuzmin, H. Yoshii, Tareq Abu-Zayyad, A. H. Tirone, R. Yamane, Kiyoshi Tanaka, J. Ogura, Naoto Sakaki, Naoaki Hayashida, Peter Tinyakov, Samuel Blake, Maxim Pshirkov, Shoichi Ogio, T.-A. Shibata, Gordon Thomson, Tom Stroman, Zach Zundel, Pierre Sokolsky, Hang Bae Kim, Akimichi Taketa, Heungsu Shin, Rasha Abbasi, M. Takeda, Fumio Kakimoto, Shigehiro Nagataki, Michiyuki Chikawa, K. Tsutsumi, R. Azuma, S. Kawakami, Hiroyuki Sagawa, Y. Uchihori, T. Suzawa, Isaac Myers, Takaaki Ishii, D. C. Rodriguez, Shingo Kawana, William Hanlon, T. Okuda, H. Tokuno, J. D. Smith, and Fumiya Shibata
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, 010308 nuclear & particles physics, Astrophysics::High Energy Astrophysical Phenomena, Galactic anticenter, FOS: Physical sciences, Astronomy, Astronomy and Astrophysics, Cosmic ray, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Galactic plane, 01 natural sciences, Galactic tide, law.invention, Telescope, law, 0103 physical sciences, Galactic corona, Astrophysics - High Energy Astrophysical Phenomena, Anisotropy, Longitude, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics
Abstract: Cosmic rays in the energy range $10^{18.0}$ - $10^{18.5}$ eV are thought to have a light, probably protonic, composition. To study their origin one can search for anisotropy in their arrival directions. Extragalactic cosmic rays should be isotropic, but galactic cosmic rays of this type should be seen mostly along the galactic plane, and there should be a shortage of events coming from directions near the galactic anticenter. This is due to the fact that, under the influence of the galactic magnetic field, the transition from ballistic to diffusive behavior is well advanced, and this qualitative picture persists over the whole energy range. Guided by models of the galactic magnetic field that indicate that the enhancement along the galactic plane should have a standard deviation of about 20$^\circ$ in galactic latitude, and the deficit in the galactic anticenter direction should have a standard deviation of about 50$^\circ$ in galactic longitude, we use the data of the Telescope Array surface detector in $10^{18.0}$ to $10^{18.5}$ eV energy range to search for these effects. The data are isotropic. Neither an enhancement along the galactic plane nor a deficit in the galactic anticenter direction is found. Using these data we place an upper limit on the fraction of EeV cosmic rays of galactic origin at 1.3% at 95% confidence level.
Published: 2017

46. Search for Ultra-High-Energy Neutrinos with the Telescope Array Surface Detector

Author: Koichi Sekino, Y. Takahashi, Mai Takamura, S. Kitamura, Hidemi Ito, K. Martens, Yuta Tanoue, Motoki Hayashi, J. P. Lundquist, K. Tsutsumi, John Belz, Heungsu Shin, Vladim Kuzmin, Takashi Sako, Toru Nakamura, Inkyu Park, Kenichi Kadota, Yana Zhezher, Hiroyuki Sagawa, D. R. Bergman, Maxim Pshirkov, Charlie Jui, BayarJon Paul Lubsandorzhiev, Mayuko Minamino, K. Yamazaki, M. Abe, K. H. Lee, K. Honda, Daisuke Ikeda, S. R. Stratton, Yasunori Kitamura, T.-A. Shibata, Gordon Thomson, Toshiyuki Fujii, Ryo Nakamura, Tom Stroman, Robert Cady, Masaaki Tanaka, Fumiya Shibata, M. Yamamoto, Nobuyuki Sakurai, Tiffany Wong, R. Takeishi, L. M. Scott, Hongsu Kim, Y. Hayashi, R. Ishimori, Masaki Fukushima, Kazuo Saito, Ben Stokes, N. Inoue, M. Ohnishi, Y. J. Kwon, Akimichi Taketa, Eiji Kido, B. G. Cheon, H. Kawai, K. Kawata, Federico R. Urban, M. V. Kuznetsov, Ryota Onogi, Hideyuki Ohoka, Pierre Sokolsky, A. Di Matteo, H. Yoshii, S. Udo, Kazuhiro Machida, Hideaki Shimodaira, Hyoming Jeong, M. Takeda, Shigehiro Nagataki, R. Mayta, T. Seki, Seok Ho Jeong, S. B. Thomas, Peter Tinyakov, Samuel Blake, Oleg Kalashev, Shoichi Ogio, Priti Shah, Igor Tkachev, Zach Zundel, S. Kawakami, Fumio Kakimoto, Tareq Abu-Zayyad, K. Nagasawa, H. Oda, H. Tokuno, R. Azuma, Toshiyuki Nonaka, K. Hibino, Kenta Yashiro, Akitoshi Oshima, Y. Tsunesada, Keitaro Fujita, B. K. Shin, H. Yamaoka, Michiyuki Chikawa, Masato Takita, J. D. Smith, Sergey Troitsky, Y. Omura, J. Remington, J. H. Kim, Elliott Barcikowski, Dmitri Ivanov, Jyunsei Chiba, Keijiro Mukai, Naoaki Hayashida, Shingo Kawana, Dongsu Ryu, Y. Takagi, Yasunori Saito, William Hanlon, T. Okuda, J. Yang, Yuichiro Tameda, John N. Matthews, Kohei Yada, Hideki Tanaka, Takayuki Tomida, K. Kasahara, Shoichi Kishigami, Kiyoshi Tanaka, Grigory Rubtsov, M. Allen, Masaomi Ono, R. Sahara, Ryota Fujiwara, Naoto Sakaki, Y. Uchihori, Kei Nakai, Rasha Abbasi, T. Matsuyama, S. Ozawa, T. Suzawa, J. Ogura, Isaac Myers, G. Furlich, Takaaki Ishii, and D. C. Rodriguez
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, business.industry, Astrophysics::High Energy Astrophysical Phenomena, Detector, FOS: Physical sciences, General Physics and Astronomy, Flux, Observable, Cosmic ray, 01 natural sciences, law.invention, Telescope, Optics, Distribution function, law, 0103 physical sciences, Alternating decision tree, High Energy Physics::Experiment, Neutrino, 010306 general physics, business, Astrophysics - High Energy Astrophysical Phenomena
Abstract: We present an upper limit on the flux of ultra-high-energy down-going neutrinos for $E > 10^{18}\ \mbox{eV}$ derived with the nine years of data collected by the Telescope Array surface detector (05-11-2008 -- 05-10-2017). The method is based on the multivariate analysis technique, so-called Boosted Decision Trees (BDT). Proton-neutrino classifier is built upon 16 observables related to both the properties of the shower front and the lateral distribution function., 10 pages, 4 figures, accepted to JETP
Published: 2019

47. Search for point sources of ultra-high energy photons with the Telescope Array surface detector

Author: Yasunori Saito, Yuichiro Tameda, John N. Matthews, G. Furlich, Takaaki Ishii, Takayuki Tomida, Heungsu Shin, D. C. Rodriguez, Fumio Kakimoto, Hideki Tanaka, Hideyuki Ohoka, Pierre Sokolsky, Elliott Barcikowski, M. Takeda, Shigehiro Nagataki, Yana Zhezher, K. Hibino, Dmitri Ivanov, Douglas Bergman, Hideaki Shimodaira, Hyoming Jeong, Keijiro Mukai, Younghoon Kwon, T. Suzawa, K. Martens, Eiji Kido, Kenta Yashiro, M. V. Kuznetsov, K. Tsutsumi, Kazuhiro Machida, K. Yamazaki, Isaac Myers, Sergey Troitsky, K. H. Lee, Grigory Rubtsov, T.-A. Shibata, Hidemi Ito, J. Remington, Gordon Thomson, BayarJon Paul Lubsandorzhiev, K. Kasahara, Tom Stroman, Shoichi Kishigami, Robert Cady, Mayuko Minamino, John Belz, Hiroyuki Sagawa, Kiyoshi Tanaka, Kuzmin, Maxim Pshirkov, K. Honda, J. H. Kim, Toshio Seki, Y. Uchihori, Kei Nakai, Masaaki Tanaka, Naoaki Hayashida, Akitoshi Oshima, Y. Tsunesada, Y. Omura, Fumiya Shibata, Masaomi Ono, Toshiyuki Nonaka, R. Sahara, M. Allen, Takashi Sako, R. Ishimori, Hongsu Kim, Toru Nakamura, Kohei Yada, Igor Tkachev, Kenichi Kadota, Inkyu Park, Shingo Kawana, Jyunsei Chiba, Dongsu Ryu, H. Oda, T. Fujii, Keitaro Fujita, Y. Takagi, Akimichi Taketa, Ben Stokes, Tareq Abu-Zayyad, N. Inoue, B. G. Cheon, H. Kawai, B. K. Shin, M. Ohnishi, Federico R. Urban, S. Udo, C. C. H. Jui, Oleg Kalashev, William Hanlon, S. B. Thomas, S. Kawakami, T. Okuda, Rasha Abbasi, Seok Ho Jeong, J. Yang, L. M. Scott, Y. Hayashi, M. Yamamoto, Priti Shah, K. Kawata, Zach Zundel, Nobuyuki Sakurai, Ryota Onogi, A. Di Matteo, Daisuke Ikeda, Ryota Fujiwara, R. Mayta, S. R. Stratton, Tiffany Wong, Naoto Sakaki, R. Takeishi, Ryo Nakamura, Kazuo Saito, Masaki Fukushima, H. Yoshii, R. Azuma, T. Matsuyama, S. Ozawa, Masato Takita, H. Yamaoka, Michiyuki Chikawa, H. Tokuno, J. D. Smith, Peter Tinyakov, Samuel Blake, Shoichi Ogio, Yuta Tanoue, Motoki Hayashi, J. P. Lundquist, Koichi Sekino, Y. Takahashi, Mai Takamura, and M. Abe
Subjects: Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Photon flux, Library science, FOS: Physical sciences, Astronomy and Astrophysics, 01 natural sciences, Joint research, High energy photon, Science research, Space and Planetary Science, 0103 physical sciences, Research policy, Science policy, Astrophysics - High Energy Astrophysical Phenomena, 010306 general physics, 010303 astronomy & astrophysics, Vice president
Abstract: The surface detector (SD) of the Telescope Array (TA) experiment allows one to indirectly detect photons with energies of order $10^{18}$ eV and higher and to separate photons from the cosmic-ray background. In this paper we present the results of a blind search for point sources of ultra-high energy (UHE) photons in the Northern sky using the TA SD data. The photon-induced extensive air showers (EAS) are separated from the hadron-induced EAS background by means of a multivariate classifier based upon 16 parameters that characterize the air shower events. No significant evidence for the photon point sources is found. The upper limits are set on the flux of photons from each particular direction in the sky within the TA field of view, according to the experiment's angular resolution for photons. Average 95% C.L. upper limits for the point-source flux of photons with energies greater than $10^{18}$, $10^{18.5}$, $10^{19}$, $10^{19.5}$ and $10^{20}$ eV are $0.094$, $0.029$, $0.010$, $0.0073$ and $0.0058$ km$^{-2}$yr$^{-1}$ respectively. For the energies higher than $10^{18.5}$ eV, the photon point-source limits are set for the first time. Numerical results for each given direction in each energy range are provided as a supplement to this paper., Comment: accepted to MNRAS, 11 pages, 4 figures, 2 tables; results in text-file format are supplemented to paper source
Published: 2019
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48. Direct Measurement of the Cosmic-Ray Proton Spectrum from 50 GeV to 10 TeV with the Calorimetric Electron Telescope on the International Space Station

Author: K. Sakai, Y. Tsunesada, Gabriele Bigongiari, Eugenio Berti, A. A. Moiseev, A. Yoshida, Brian Rauch, Y. Katayose, Shinji Ueno, J. P. Wefel, T. G. Guzik, J. H. Buckley, F. Stolzi, K. Mori, Y. Kawakubo, J. F. Ormes, W. R. Binns, Y. Shimizu, Paolo Maestro, Henric Krawczynski, Ryuho Kataoka, M. Bongi, Yoichi Asaoka, N. Cannady, T. Hams, G. Castellini, Shohei Yanagita, Satoshi Nakahira, S. Okuno, Shoji Torii, J. E. Suh, N. Mori, Kenji Yoshida, Holger Motz, K. Hibino, Y. Uchihori, M. Ichimura, Norita Kawanaka, M. H. Israel, G. Collazuol, Maria Grazia Bagliesi, F. Palma, Teimuraz Lomtadze, G. A. de Nolfo, Y. Akaike, K. Ebisawa, L. Pacini, Katsuaki Asano, S. Bonechi, A. V. Penacchioni, O. Adriani, S. B. Ricciarini, Michael Cherry, Kunihito Ioka, R. Sparvoli, T. Tamura, Masaki Mori, K. Kasahara, Manami Sasaki, H. Murakami, T. Sakamoto, P. Papini, N. Hasebe, E. Vannuccini, Kazuoki Munakata, Jun Kataoka, Jun Nishimura, V. Di Felice, Kazunori Kohri, Masahiro Takayanagi, Kazutaka Yamaoka, H. Tomida, A. Bruno, Masato Takita, Chihiro Kato, S. Ozawa, P. Spillantini, W. Ishizaki, Alberto Messineo, C. Checchia, Toshio Terasawa, P. S. Marrocchesi, John Mitchell, John F. Krizmanic, A. Sulaj, I. Takahashi, A. Shiomi, H. Fuke, Paolo Brogi, and S. Miyake
Subjects: Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, General Physics and Astronomy, CALET, Cosmic ray, Electron, Calorimetry, 01 natural sciences, Power law, International Space Station, law.invention, SUPERNOVA-REMNANTS, ENERGY, COMPONENT, Telescope, Nuclear physics, Cosmic ray measurement, law, 0103 physical sciences, Cosmic Ray Proton Spectrum, 010306 general physics, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Spectral index, Spectrometer, Settore FIS/04, Space stations, Cosmic Ray Proton Spectrum, CALET Experiment, International Space Station, Spectrum analysis, CALET Experiment, Astrophysics - High Energy Astrophysical Phenomena, Nucleon
Abstract: 著者人数: CALET Collaboration 100名 (所属. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS): 海老沢, 研; 福家, 英之; 森, 国城; 西村, 純; 高柳, 昌弘; 冨田, 洋; 上野, 史郎), Number of authors: 100 (Affiliation. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS): Ebisawa, Ken; Fuke, Hideyuki; Mori, Kunishiro; Nishimura, Jun; Takayanagi, Masahiro; Tomida, Hiroshi; Ueno, Shiro), 資料番号: SA1190040000
Published: 2019

49. The CALorimetric Electron Telescope (CALET) on the international space station: Results from the first two years on orbit

Author: A. M. Messineo, G. Castellini, A. Sulaj, N. Tateyama, F. Stolzi, Paolo Papini, G. A. de Nolfo, Shunsuke Ozawa, Seiya Ueno, P. Brogi, L. Pacini, Nicola Mori, J. E. Suh, Y. Katayose, Holger Motz, T. G. Guzik, V. Pal'shin, Satoshi Sugita, P. Spillantini, Katsuaki Kasahara, S. Yanagita, K. Hibino, Nobuyuki Hasebe, Chihiro Kato, Y. Kawakubo, Shoji Torii, Ryuho Kataoka, Hideyuki Fuke, Roberta Sparvoli, S. Bonechi, John Mitchell, Henric Krawczynski, N. Cannady, Shoko Miyake, G. Bigongiari, John Krizmanic, M. H. Israel, Kazutaka Yamaoka, A. Shiomi, Kazuoki Munakata, E. Vannuccini, Y. Shimizu, Atsumasa Yoshida, J. F. Ormes, M. Bongi, Yoichi Asaoka, Wataru Ishizaki, Yukio Uchihori, Maria Grazia Bagliesi, H. Tomida, T. Hams, J. Nishimura, Emanuele Berti, Kenji Yoshida, M. Ichimura, T. Lomtadze, G. Collazuol, Toshio Terasawa, Katsuaki Asano, H. Murakami, C. Checchia, Yoshiki Tsunesada, W. R. Binns, Kazunori Kohri, K. Sakai, V. Di Felice, Alexander Moiseev, J. Kataoka, A. Bruno, A. V. Penacchioni, T. Tamura, Manami Sasaki, J. H. Buckley, O. Adriani, Kunihito Ioka, T. Sakamoto, Masato Takita, Y Akaike, I. Takahashi, S. B. Ricciarini, Michael Cherry, Masaki Mori, Satoshi Nakahira, K. Mori, P. Maestro, Brian Rauch, M. Takayanagi, John P. Wefel, Norita Kawanaka, F. Palma, Ken Ebisawa, S. Okuno, and P. S. Marrocchesi
Subjects: History, Astrophysics::High Energy Astrophysical Phenomena, Dark matter, FOS: Physical sciences, astro-ph.HE, International Space stations, 01 natural sciences, 7. Clean energy, Education, law.invention, Telescope, Positron, law, 0103 physical sciences, International Space Station, Gamma-ray observations, 010306 general physics, 010303 astronomy & astrophysics, Settore FIS/01, High Energy Astrophysical Phenomena (astro-ph.HE), Astroparticle physics, Physics, Cosmic ray electrons, Gravitational wave, Gamma rays, Astronomy, LIGO, Computer Science Applications, Particle acceleration, Astrophysics - High Energy Astrophysical Phenomena, Telescopes
Abstract: The CALorimetric Electron Telescope (CALET) is a high-energy astroparticle physics space experiment installed on the International Space Station (ISS), developed and operated by Japan in collaboration with Italy and the United States. The CALET mission goals include the investigation of possible nearby sources of high-energy electrons, of the details of galactic particle acceleration and propagation, and of potential signatures of dark matter. CALET measures the cosmic-ray electron + positron flux up to 20 TeV, gamma-rays up to 10 TeV, and nuclei with Z=1 to 40 up to 1,000 TeV for the more abundant elements during a long-term observation aboard the ISS. Starting science operation in mid-October 2015, CALET performed continuous observation without major interruption with close to 20 million triggered events over 10 GeV per month. Based on the data taken during the first two-years, we present an overview of CALET observations: uses w/o major interruption 1) Electron + positron energy spectrum, 2) Nuclei analysis, 3) Gamma-ray observation including a characterization of on-orbit performance. Results of the electromagnetic counterpart search for LIGO/Virgo gravitational wave events are discussed as well., 10 pages, 10 figures, a contribution to the proceedings of 26th Extended European Cosmic Ray Symposium, 6-10 July 2018, Russia, which summarizes our recent publications such as arXiv:1712.01711, arXiv:1712.01757, arXiv:1803.05834, arXiv:1806.09728, and arXiv:1807.01435
Published: 2019

50. The Cosmic-Ray Composition between 2 PeV and 2 EeV Observed with the TALE Detector in Monocular Mode

Author: BayarJon Paul Lubsandorzhiev, Mayuko Minamino, K. Honda, Masaaki Tanaka, Ryuji Takeishi, Hiroyuki Sagawa, Yasunori Saito, Pierre Sokolsky, B. K. Shin, M. Takeda, M. Yamamoto, Shigehiro Nagataki, R. Sahara, Toshiyuki Fujii, Shingo Kawana, William Hanlon, T. Okuda, J. Yang, M. Allen, Seok Ho Jeong, Nobuyuki Sakurai, K. H. Lee, T.-A. Shibata, Shoichi Kishigami, Yuichiro Tameda, John N. Matthews, Zach Zundel, T. Suzawa, Fugo Yoshida, Gordon Thomson, Tom Stroman, Fumiya Shibata, Ryota Onogi, Saori Kasami, D. Ikeda, Robert Cady, S. W. Kim, Ryosuke Tsuda, Isaac Myers, Hidemi Ito, R. Mayta, Masaomi Ono, H. Kawai, K. Kawata, N. Inoue, B. G. Cheon, Katsuaki Kasahara, J. H. Kim, Takashi Sako, T. Seki, Kiyoshi Tanaka, Koichi Sekino, M. Ohnishi, Min Hyo Kim, Takayuki Tomida, Grigory Rubtsov, Hideki Tanaka, Peter Tinyakov, Samuel Blake, Toshiyuki Nonaka, Taichi Inadomi, Norimichi Shibata, Y. Omura, Hideaki Shimodaira, Hyoming Jeong, Shoichi Ogio, Younghoon Kwon, Inkyu Park, John Belz, T. Matsuyama, Ryo Higuchi, Ryota Fukushima, S. Ozawa, Katsuya Yamazaki, Y. Nakamura, Federico R. Urban, Heungsu Shin, Kohei Yada, S. Kawakami, Keitaro Fujita, Y. Takahashi, Mai Takamura, Elliott Barcikowski, R. U. Abbasi, Y. Uchihori, Kei Nakai, Maxim Pshirkov, Dmitri Ivanov, S. Udo, C. C. H. Jui, Koki Sato, Tiffany Wong, Yuto Arai, Keijiro Mukai, Hiroyuki Matsumiya, Masaki Fukushima, Yusuke Kimura, Akimichi Taketa, Yuta Tanoue, Ryota Fujiwara, M. Chikawa, Takafumi Uehama, Tareq Abu-Zayyad, Motoki Hayashi, G. Furlich, Takaaki Ishii, J. P. Lundquist, Jyunsei Chiba, Naoto Sakaki, Daiki Shinto, Eiji Kido, M. V. Kuznetsov, Kazuhiro Machida, D. C. Rodriguez, Kozo Fujisue, Kengo Sano, Priti Shah, Dongsu Ryu, S. B. Thomas, Hirokazu Iwakura, Y. Takagi, Igor Tkachev, Naohiro Sone, H. Oda, Kenta Yashiro, Masato Takita, F. Kakimoto, Hongsu Kim, Sergey Troitsky, J. Remington, Naoaki Hayashida, Akitoshi Oshima, Y. Tsunesada, Ben Stokes, Y. Zhezher, Hideyuki Ohoka, Vladim Kuzmin, Toru Nakamura, Kenichi Kadota, M. Abe, Yuya Oku, Oleg Kalashev, Ryo Nakamura, D. R. Bergman, K. Hibino, H. Tokuno, and J. D. Smith
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Astroparticle physics, Physics, Monocular, Astrophysics::High Energy Astrophysical Phenomena, Detector, Mode (statistics), FOS: Physical sciences, Astronomy and Astrophysics, Cosmic ray, Astrophysics, 030226 pharmacology & pharmacy, 01 natural sciences, 03 medical and health sciences, 0302 clinical medicine, Space and Planetary Science, 0103 physical sciences, Astrophysics - High Energy Astrophysical Phenomena, 010303 astronomy & astrophysics
Abstract: We report on a measurement of the cosmic ray composition by the Telescope Array Low-Energy Extension (TALE) air fluorescence detector (FD). By making use of the Cherenkov light signal in addition to air fluorescence light from cosmic ray (CR) induced extensive air showers, the TALE FD can measure the properties of the cosmic rays with energies as low as $\sim 2$ PeV and exceeding 1 EeV. In this paper, we present results on the measurement of $X_{\rm max}$ distributions of showers observed over this energy range. Data collected over a period of $\sim 4$ years was analyzed for this study. The resulting $X_{\rm max}$ distributions are compared to the Monte Carlo (MC) simulated data distributions for primary cosmic rays with varying composition and a 4-component fit is performed. The comparison and fit are performed for energy bins, of width 0.1 or 0.2 in $\log_{10} (E/{\rm eV})$, spanning the full range of the measured energies. We also examine the mean $X_{\rm max}$ value as a function of energy for cosmic rays with energies greater than $10^{15.8}$ eV. Below $10^{17.3}$ eV, the slope of the mean $X_{\rm max}$ as a function of energy (the elongation rate) for the data is significantly smaller than that of all elements in the models, indicating that the composition is becoming heavier with energy in this energy range. This is consistent with a rigidity-dependent cutoff of events from galactic sources. Finally, an increase in the $X_{\rm max}$ elongation rate is observed at energies just above $10^{17}$ eV indicating another change in the cosmic rays composition., 20 pages, 22 figures, accepted for publication in ApJ
Published: 2021

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