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1. Isotropy of cosmic rays beyond $10^{20}$ eV favors their heavy mass composition

Author

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

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We report an estimation of the injected mass composition of ultra-high energy cosmic rays (UHECRs) at energies higher than 10 EeV. The composition is inferred from an energy-dependent sky distribution of UHECR events observed by the Telescope Array surface detector by comparing it to the Large Scale Structure of the local Universe. In the case of negligible extra-galactic magnetic fields the results are consistent with a relatively heavy injected composition at E ~ 10 EeV that becomes lighter up to E ~ 100 EeV, while the composition at E > 100 EeV is very heavy. The latter is true even in the presence of highest experimentally allowed extra-galactic magnetic fields, while the composition at lower energies can be light if a strong EGMF is present. The effect of the uncertainty in the galactic magnetic field on these results is subdominant., Comment: 8 pages, 3 figures, accepted for publication in PRL

Published
2024

2. Mass composition of ultra-high energy cosmic rays from distribution of their arrival directions with the Telescope Array

Author

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

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We use a new method to estimate the injected mass composition of ultrahigh cosmic rays (UHECRs) at energies higher than 10 EeV. The method is based on comparison of the energy-dependent distribution of cosmic ray arrival directions as measured by the Telescope Array experiment (TA) with that calculated in a given putative model of UHECR under the assumption that sources trace the large-scale structure (LSS) of the Universe. As we report in the companion letter, the TA data show large deflections with respect to the LSS which can be explained, assuming small extra-galactic magnetic fields (EGMF), by an intermediate composition changing to a heavy one (iron) in the highest energy bin. Here we show that these results are robust to uncertainties in UHECR injection spectra, the energy scale of the experiment and galactic magnetic fields (GMF). The assumption of weak EGMF, however, strongly affects this interpretation at all but the highest energies E > 100 EeV, where the remarkable isotropy of the data implies a heavy injected composition even in the case of strong EGMF. This result also holds if UHECR sources are as rare as $2 \times 10^{-5}$ Mpc$^{-3}$, that is the conservative lower limit for the source number density., Comment: 18 pages, 11 figures, accepted for publication in PRD

Published
2024

3. Observation of Declination Dependence in the Cosmic Ray Energy Spectrum

Author

The Telescope Array Collaboration, Abbasi, R. U., Abu-Zayyad, T., Allen, M., Belz, J. W., Bergman, D. R., Buckland, I., Campbell, W., Cheon, B. G., Endo, K., Fedynitch, A., Fujii, T., Fujisue, K., Fujita, K., Fukushima, M., Furlich, G., Gerber, Z., Globus, N., Hanlon, W., Hayashida, N., He, H., Hibino, K., Higuchi, R., Ikeda, D., Ishii, T., Ivanov, D., Jeong, S., Jui, C. C. H., Kadota, K., Kakimoto, F., Kalashev, O., Kasahara, K., Kawachi, Y., Kawata, K., Kharuk, I., Kido, E., Kim, H. B., Kim, J. H., Kim, S. W., Kobo, R., Komae, I., Komatsu, K., Komori, K., Koyama, C., Kudenko, M., Kuroiwa, M., Kusumori, Y., Kuznetsov, M., Kwon, Y. J., Lee, K. H., Lee, M. J., Lubsandorzhiev, B., Lundquist, J. P., Matsuzawa, A., Matthews, J. A., Matthews, J. N., Mizuno, K., Mori, M., Murakami, M., Nagataki, S., Nakahara, M., Nakamura, T., Nakayama, T., Nakayama, Y., Nonaka, T., Ogio, S., Ohoka, H., Okazaki, N., Onishi, M., Oshima, A., Oshima, H., Ozawa, S., Park, I. H., Park, K. Y., Potts, M., Przybylak, M., Pshirkov, M. S., Remington, J., Rott, C., Rubtsov, G. I., Ryu, D., Sagawa, H., Sakaki, N., Sakamoto, R., Sako, T., Sakurai, N., Sakurai, S., Sato, D., Sato, S., Sekino, K., Shibata, T., Shikita, J., Shimodaira, H., Shin, B. K., Shin, H. S., Shinozaki, K., Smith, J. D., Sokolsky, P., Stokes, B. T., Stroman, T. A., Takagi, Y., Takahashi, K., Takeda, M., Takeishi, R., Taketa, A., Takita, M., Tameda, Y., Tanaka, K., Tanaka, M., Thomas, S. B., Thomson, G. B., Tinyakov, P., Tkachev, I., Tomida, T., Troitsky, S., Tsunesada, Y., Udo, S., Urban, F., Vaiman, I. A., Vrábel, M., Warren, D., Yamazaki, K., Zhezher, Y., Zundel, Z., and Zvirzdin, J.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We report on an observation of the difference between northern and southern skies of the ultrahigh energy cosmic ray energy spectrum with a significance of ${\sim}8\sigma$. We use measurements from the two largest experiments$\unicode{x2014}$the Telescope Array observing the northern hemisphere and the Pierre Auger Observatory viewing the southern hemisphere. Since the comparison of two measurements from different observatories introduces the issue of possible systematic differences between detectors and analyses, we validate the methodology of the comparison by examining the region of the sky where the apertures of the two observatories overlap. Although the spectra differ in this region, we find that there is only a $1.8\sigma$ difference between the spectrum measurements when anisotropic regions are removed and a fiducial cut in the aperture is applied., Comment: 8 pages, 6 figures

Published
2024

4. Characteristics of temporal variability of long-duration bursts of high-energy radiation associated with thunderclouds on the Tibetan plateau

Author

Tsuchiya, H., Hibino, K., Kawata, K., Ohnishi, M., Takita, M., Munakata, K., Kato, C., Shimoda, S., Shi, Q., Wang, S., Han, C., and Zhai, L.

Subjects
Physics - Geophysics, Astrophysics - Earth and Planetary Astrophysics, Physics - Atmospheric and Oceanic Physics
Abstract

From 1998 to 2017, neutron monitors located at an altitude of 4300 m on the Tibetan plateau detected 127 long-duration bursts of high-energy radiation in association with thunderclouds. These bursts typically lasted for 10 to 40 minutes, and 89\% of them occurred between 10:00 and 24:00 local time. They were also found to be more likely to occur at night, especially during 18:00$-$06:00 local time period. The observed diurnal and seasonal variations in burst frequency were consistent with the frequencies of lightning and precipitation on the Tibetan plateau. Based on 19 years of data, the present study suggests that an annual variation in burst frequency has a periodicity of $\sim$16 years and a lag of $\sim$3 years relative to solar activity., Comment: 28 pages, accepted for publication in Progress in Earth and Planetary Science

Published
2024
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5. On the source contribution to the Galactic diffuse gamma rays above 398 TeV detected by the Tibet AS{\gamma} experiment

Author

Kato, S., Chen, D., Huang, J., Kawashima, T., Kawata, K., Mizuno, A., Ohnishi, M., Sako, T., Sako, T. K., Takita, M., and Yokoe, Y.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Potential contribution from gamma-ray sources to the Galactic diffuse gamma rays observed above 100 TeV (sub-PeV energy range) by the Tibet AS{\gamma} experiment is an important key to interpreting recent multi-messenger observations. This paper reveals a surprising fact: none of the 23 Tibet AS{\gamma} diffuse gamma-ray events above 398TeV within the Galactic latitudinal range of |b| < 10 deg. come from the 43 sub-PeV gamma-ray sources reported in the 1LHAASO catalog, which proves that these sources are not the origins of the Tibet AS{\gamma} diffuse gamma-ray events. No positional overlap between the Tibet AS{\gamma} diffuse gamma-ray events and the sub-PeV LHAASO sources currently supports the diffusive nature of the Tibet AS{\gamma} diffuse gamma-ray events, although their potential origin in the gamma-ray sources yet unresolved in the sub-PeV energy range cannot be ruled out., Comment: 5 pages, 2 figures Accepted for publication from The Astrophysical Journal Letters. arXiv admin note: text overlap with arXiv:2309.16078

Published
2024

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

Author

Adriani, O., Akaike, Y., Asano, K., Asaoka, Y., Berti, E., Bigongiari, G., Binns, W. R., Bongi, M., Brogi, P., Bruno, A., Buckley, J. H., Cannady, N., Castellini, G., Checchia, C., Cherry, M. L., Collazuol, G., de Nolfo, G. A., Ebisawa, K., Ficklin, A. W., Fuke, H., Gonzi, S., Guzik, T. G., Hams, T., Hibino, K., Ichimura, M., Ioka, K., Ishizaki, W., Israel, M. H., Kasahara, K., Kataoka, J., Kataoka, R., Katayose, Y., Kato, C., Kawanaka, N., Kawakubo, Y., Kobayashi, K., Kohri, K., Krawczynski, H. S., Krizmanic, J. F., Maestro, P., Marrocchesi, P. S., Messineo, A. M., Mitchell, J. W., Miyake, S., Moiseev, A. A., Mori, M., Mori, N., Motz, H. M., Munakata, K., Nakahira, S., Nishimura, J., Okuno, S., Ormes, J. F., Ozawa, S., Pacini, L., Papini, P., Rauch, B. F., Ricciarini, S. B., Sakai, K., Sakamoto, 3 T., Sasaki, M., Shimizu, Y., Shiomi, A., Spillantini, P., Stolzi, F., Sugita, S., Sulaj, A., Takita, M., Tamura, T., Terasawa, T., Torii, S., Tsunesada, Y., Uchihori, Y., Vannuccini, E., Wefel, J. P., Yamaoka, K., Yanagita, S., Yoshida, A., Yoshida, K., and Zober, W. V.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Detailed measurements of the spectral structure of cosmic-ray electrons and positrons from 10.6 GeV to 7.5 TeV are presented from over 7 years of observations with the CALorimetric Electron Telescope (CALET) on the International Space Station. Because of the excellent energy resolution (a few percent above 10 GeV) and the outstanding e/p separation (10$^5$), CALET provides optimal performance for a detailed search of structures in the energy spectrum. The analysis uses data up to the end of 2022, and the statistics of observed electron candidates has increased more than 3 times since the last publication in 2018. By adopting an updated boosted decision tree analysis, a sufficient proton rejection power up to 7.5 TeV is achieved, with a residual proton contamination less than 10%. The observed energy spectrum becomes gradually harder in the lower energy region from around 30 GeV, consistently with AMS-02, but from 300 to 600 GeV it is considerably softer than the spectra measured by DAMPE and Fermi-LAT. At high energies, the spectrum presents a sharp break around 1 TeV, with a spectral index change from -3.15 to -3.91, and a broken power law fitting the data in the energy range from 30 GeV to 4.8 TeV better than a single power law with 6.9 sigma significance, which is compatible with the DAMPE results. The break is consistent with the expected effects of radiation loss during the propagation from distant sources (except the highest energy bin). We have fitted the spectrum with a model consistent with the positron flux measured by AMS-02 below 1 TeV and interpreted the electron + positron spectrum with possible contributions from pulsars and nearby sources. Above 4.8 TeV, a possible contribution from known nearby supernova remnants, including Vela, is addressed by an event-by-event analysis providing a higher proton-rejection power than a purely statistical analysis., Comment: main text: 7 pages, 4 figures; supplemental material: 10 pages, 8 figures, 1 table

Published
2023
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7. Nobeyama Cygnus-X Survey: Physical Properties of C$^{18}$O clumps in DR-6(W), DR-9 and DR-13S regions

Author

Toledano--Juárez, I., de la Fuente, E., Kawata, K., Trinidad, M. A., Tafoya, D., Yamagishi, M., Takekawa, S., Ohnishi, M., Nishimura, A., Kato, S., Sako, T., Takita, M., and Yadav, R. K.

Subjects
Astrophysics - Astrophysics of Galaxies, Astrophysics - Solar and Stellar Astrophysics
Abstract

Cygnus-X is considered a region of interest for high-energy astrophysics, since the Cygnus OB2 association has been confirmed as a PeVatron in the Cygnus cocoon. In this research note, we present new high-resolution (16'') $^{12,13}$CO(J=1$\rightarrow$0) and C$^{18}$O (J=1$\rightarrow$0) observations obtained with the Nobeyama 45-m radiotelescope, to complement the Nobeyama Cygnus-X Survey. We discovered 19 new C$^{18}$O clumps associated with the star-forming regions DR-6W, DR-9, and DR13S. We present the physical parameters of these clumps, which are consistent with the neighboring covered regions. We confirm the clumpy nature of these regions and of a filament located between DR6 and DR6W. These results strongly suggest that star formation occurs in these regions with clumps of sizes $\sim$10$^{-1}$ pc, masses $\sim$10$^2$ M$_\odot$, and H$_2$ densities of $\sim$10$^4$ cm$^{-3}$., Comment: 8 pages, 3 Figures, 1 Table. https://pos.sissa.it/444/631/pdf

Published
2023

8. Quantitative constraint on the source contribution to the Galactic diffuse gamma rays detected by the Tibet air shower array

Author

Kato, S., Chen, D., Huang, J., Kawashima, T., Kawata, K., Mizuno, A., Ohnishi, M., Sako, T., Sako, T. K., Takita, M., and Yokoe, Y.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

The fraction of the contribution from yet-unresolved gamma-ray sources in the Galactic diffuse gamma rays observed by the Tibet air shower array is an important key to interpreting recent multi-messenger observations. This paper shows a surprising fact: no Tibet diffuse events above 398TeV come from the gamma-ray sources newly detected above 100 TeV by LHAASO. Based on this observational fact, the contribution of sources unresolved by LHAASO to the Tibet diffuse events is estimated to be less than 31% above 398TeV with a 99% confidence level. Our result shows that unresolved sources make only a sub-dominant contribution to the Tibet diffuse events above 398 TeV and a large fraction of the events are truly a diffusive nature., Comment: Calculations in Eq-(2) should have used the probability p that a Tibet diffuse gamma-ray event is of unresolved-source origin, but the parameter p in Eq-(2) is the probability that a gamma-ray event above 398 TeV from a source marginally detected by LHAASO is detected by the Tibet. This mistake leads to a wrong estimate of the limit on the source fraction to the Tibet diffuse gamma-ray events

Published
2023

9. Observation of gamma rays up to 320 TeV from the middle-aged TeV pulsar wind nebula HESS J1849$-$000

Author

Amenomori, M., Asano, S., Bao, Y. W., Bi, X. J., Chen, D., Chen, T. L., Chen, W. Y., Chen, Xu, Chen, Y., Cirennima, Cui, S. W., Danzengluobu, Ding, L. K., Fang, J. H., Fang, K., Feng, C. F., Feng, Zhaoyang, Feng, Z. Y., Gao, Qi, Gomi, A., Gou, Q. B., Guo, Y. Q., Guo, Y. Y., Hayashi, Y., He, H. H., He, Z. T., Hibino, K., Hotta, N., Hu, Haibing, Hu, H. B., Hu, K. Y., Huang, J., Jia, H. Y., Jiang, L., Jiang, P., Jin, H. B., Kasahara, K., Katayose, Y., Kato, C., Kato, S., Kawahara, I., Kawashima, T., Kawata, K., Kozai, M., Kurashige, D., Labaciren, Le, G. M., Li, A. F., Li, H. J., Li, W. J., Li, Y., Lin, Y. H., Liu, B., Liu, C., Liu, J. S., Liu, L. Y., Liu, M. Y., Liu, W., Lu, H., Meng, X. R., Meng, Y., Munakata, K., Nagaya, K., Nakamura, Y., Nakazawa, Y., Nanjo, H., Ning, C. C., Nishizawa, M., Noguchi, R., Ohnishi, M., Okukawa, S., Ozawa, S., Qian, X., Qian, X. L., Qu, X. B., Saito, T., Sakakibara, Y., Sakata, M., Sako, T., Sako, T. K., Sasaki, T., Shao, J., Shibata, M., Shiomi, A., Sugimoto, H., Takano, W., Takita, M., Tan, Y. H., Tateyama, N., Torii, S., Tsuchiya, H., Udo, S., Wang, H., Wang, S. F., Wang, Y. P., Wangdui, Wu, H. R., Wu, Q., Xu, J. L., Xue, L., Yang, Z., Yao, Y. Q., Yin, J., Yokoe, Y., Yu, Y. L., Yuan, A. F., Zhai, L. M., Zhang, H. M., Zhang, J. L., Zhang, X., Zhang, X. Y., Zhang, Y., Zhang, Yi, Zhang, Ying, Zhao, S. P., Zhaxisangzhu, Zhou, X. X., and Zou, Y. H.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
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 $4.0\, \sigma$ and $4.4\, \sigma$ levels above 25 TeV and 100 TeV, respectively, in units of Gaussian standard deviation $\sigma$. The energy spectrum measured between $40\, {\rm TeV} < E < 320\, {\rm TeV}$ for the first time is described with a simple power-law function of ${\rm d}N/{\rm d}E = (2.86 \pm 1.44) \times 10^{-16}(E/40\, {\rm TeV})^{-2.24 \pm 0.41}\, {\rm TeV}^{-1}\, {\rm cm}^{-2}\, {\rm s}^{-1}$. The gamma-ray energy spectrum from the sub-TeV ($E < 1\, {\rm TeV}$) to sub-PeV ($100\, {\rm TeV} < E < 1\, {\rm PeV}$) ranges including the results of previous studies can be modeled with the leptonic scenario, 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 $E_{\rm p\, cut}$, cut is estimated at ${\rm log}_{10}(E_{\rm p,\, cut}/{\rm TeV}) = 3.73^{+2.98}_{-0.66}$, 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 for a Galactic PeV cosmic-ray accelerator, PeVatron., Comment: 10 pages, 2 figures, Accepted for publication from the Astrophysical Journal

Published
2023
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10. Measurement of the Gamma-Ray Energy Spectrum beyond 100 TeV from the HESS J1843$-$033 Region

Author

Amenomori, M., Asano, S., Bao, Y. W., Bi, X. J., Chen, D., Chen, T. L., Chen, W. Y., Chen, Xu, Chen, Y., Cirennima, Cui, S. W., Danzengluobu, Ding, L. K., Fang, J. H., Fang, K., Feng, C. F., Feng, Zhaoyang, Feng, Z. Y., Gao, Qi, Gomi, A., Gou, Q. B., Guo, Y. Q., Guo, Y. Y., He, H. H., He, Z. T., Hibino, K., Hotta, N., Hu, Haibing, Hu, H. B., Hu, K. Y., Huang, J., Jia, H. Y., Jiang, L., Jiang, P., Jin, H. B., Kasahara, K., Katayose, Y., Kato, C., Kato, S., Kawashima, T., Kawata, K., Kozai, M., Kurashige, D., Labaciren, Le, G. M., Li, A. F., Li, H. J., Li, W. J., Li, Y., Lin, Y. H., Liu, B., Liu, C., Liu, J. S., Liu, L. Y., Liu, M. Y., Liu, W., Liu, X. L., Lou, Y. -Q., Lu, H., Meng, X. R., Meng, Y., Munakata, K., Nagaya, K., Nakamura, Y., Nakazawa, Y., Nanjo, H., Ning, C. C., Nishizawa, M., Ohnishi, M., Okukawa, S., Ozawa, S., Qian, L., Qian, X., Qian, X. L., Qu, X. B., Saito, T., Sakakibara, Y., Sakata, M., Sako, T., Sako, T. K., Shao, J., Shibata, M., Shiomi, A., Sugimoto, H., Takano, W., Takita, M., Tan, Y. H., Tateyama, N., Torii, S., Tsuchiya, H., Udo, S., Wang, H., Wang, Y. P., Wangdui, Wu, H. R., Wu, Q., Xu, J. L., Xue, L., Yang, Z., Yao, Y. Q., Yin, J., Yokoe, Y., Yu, N. P., Yuan, A. F., Zhai, L. M., Zhang, C. P., Zhang, H. M., Zhang, J. L., Zhang, X., Zhang, X. Y., Zhang, Y., Zhang, Yi, Zhang, Ying, Zhao, S. P., Zhaxisangzhu, and Zhou, X. X.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
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 $100\, {\rm TeV}$ 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 $0.34^{\circ} \pm 0.12^{\circ}$ is successfully detected above $25\, {\rm TeV}$ at $(\alpha,\, \delta) = (281.09^{\circ}\pm 0.10^{\circ},\, -3.76^{\circ}\pm 0.09^{\circ})$ near HESS J1843$-$033 with a statistical significance of $6.2\, \sigma$, 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 $25\, {\rm TeV} < E < 130\, {\rm TeV}$ is described with ${\rm d}N/{\rm d}E = (9.70\pm 1.89)\times 10^{-16} (E/40\, {\rm TeV})^{-3.26\pm 0.30}\, {\rm TeV}^{-1} {\rm cm}^{-2} {\rm s}^{-1}$, 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 $49.5\pm 9.0\, {\rm TeV}$. Associations of TASG J1844-038 with SNR G28.6$-$0.1 and PSR J1844-0346 are also discussed in detail for the first time., Comment: 11 pages, 4 figures, 1 table

Published
2023
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11. Charge-Sign Dependent Cosmic-Ray Modulation Observed with the Calorimetric Electron Telescope on the International Space Station

Author

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

Subjects
Astrophysics - High Energy Astrophysical Phenomena
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., Comment: main text: 6 pages, 3 figures, supplemental material: 8 pages, 3 figures, 1 table

Published
2023
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12. 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

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

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We present the results of a direct measurement of the cosmic-ray helium spectrum with the CALET instrument in operation on the International Space Station since 2015. The observation period covered by this analysis spans from October 13, 2015 to April 30, 2022 (2392 days). The very wide dynamic range of CALET allowed to collect helium data over a large energy interval, from ~40 GeV to ~250 TeV, for the first time with a single instrument in Low Earth Orbit. The measured spectrum shows evidence of a deviation of the flux from a single power-law by more than 8$\sigma$ with a progressive spectral hardening from a few hundred GeV to a few tens of TeV. This result is consistent with the data reported by space instruments including PAMELA, AMS-02, DAMPE and balloon instruments including CREAM. At higher energy we report the onset of a softening of the helium spectrum around 30 TeV (total kinetic energy). Though affected by large uncertainties in the highest energy bins, the observation of a flux reduction turns out to be consistent with the most recent results of DAMPE. A Double Broken Power Law (DBPL) is found to fit simultaneously both spectral features: the hardening (at lower energy) and the softening (at higher energy). A measurement of the proton to helium flux ratio in the energy range from 60 GeV/n to about 60 TeV/n is also presented, using the CALET proton flux recently updated with higher statistics.

Published
2023
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13. 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

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

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We present the measurement of the energy dependence of the boron flux in cosmic rays and its ratio to the carbon flux \textcolor{black}{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 $\sim 6.4$ years 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 $E_0 \sim 200$ 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 $\gamma = -3.047\pm0.024$ in the interval $25 < E < 200$ GeV$/n$. The B spectrum hardens by $\Delta \gamma_B=0.25\pm0.12$, while the best fit value for the spectral variation of C is $\Delta \gamma_C=0.19\pm0.03$. The B/C flux ratio is compatible with a hardening of $0.09\pm0.05$, 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 $\lambda_0$ of the mean escape path length $\lambda$ at high energy. We find that our B/C data are compatible with a non-zero value of $\lambda_0$, which can be interpreted as the column density of matter that cosmic rays cross within the acceleration region., Comment: main text: 7 pages, 3 figures; supplemental material: 13 pages, 8 figures, 3 tables

Published
2022
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14. 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

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

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

A precise measurement of the cosmic-ray proton spectrum with the Calorimetric Electron Telescope (CALET) is presented in the energy interval from 50 GeV to 60 TeV, and the observation of a softening of the spectrum above 10 TeV is reported. The analysis is based on the data collected during $\sim$6.2 years of smooth operations aboard the International Space Station and covers a broader energy range with respect to the previous proton flux measurement by CALET, with an increase of the available statistics by a factor of $\sim$2.2. Above a few hundred GeV we confirm our previous observation of a progressive spectral hardening with a higher significance (more than 20 sigma). In the multi-TeV region we observe a second spectral feature with a softening around 10 TeV and a spectral index change from =2.6 to -2.9 consistently, within the errors, with the shape of the spectrum reported by DAMPE. We apply a simultaneous fit of the proton differential spectrum which well reproduces the gradual change of the spectral index encompassing the lower energy power-law regime and the two spectral features observed at higher energies., Comment: main text: 8 pages, 5 figures, supplemental material: 9 pages, 7 figures, 1 table, marked as a PRL Editor's Suggestion

Published
2022
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15. CALET Search for electromagnetic counterparts of gravitational waves during the LIGO/Virgo O3 run

Author

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

Subjects
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., Comment: 27 pages, 10 figures. Accepted for publication in ApJ

Published
2022
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16. First High-speed Video Camera Observations of a Lightning Flash Associated with a Downward Terrestrial Gamma-ray Flash

Author

Abbasi, R. U., Saba, M. M. F., Belz, J. W., Krehbiel, P. R., Rison, W., Kieu, N., da Silva, D. R., Rodeheffer, Dan, Stanley, M. A., Remington, J., Mazich, J., LeVon, R., Smout, K., Petrizze, A., Abu-Zayyad, T., Allen, M., Arai, Y., Arimura, R., Barcikowski, E., Bergman, D. R., Blake, S. A., Buckland, I., Cheon, B. G., Chikawa, M., Fujii, T., Fujisue, K., Fujita, K., Fujiwara, R., Fukushima, M., Furlich, G., Globus, N., Gonzalez, R., Hanlon, W., Hayashida, N., He, H., Hibino, K., Higuchi, R., Honda, K., Ikeda, D., Inoue, N., Ishii, T., Ito, H., Ivanov, D., Iwakura, H., Iwasaki, A., Jeong, H. M., Jeong, S., Jui, C. C. H., Kadota, K., Kakimoto, F., Kalashev, O., Kasahara, K., Kasami, S., Kawakami, S., Kawata, K., Kharuk, I., Kido, E., Kim, H. B., Kim, J. H., Kim, S. W., Kimura, Y., Komae, I., Kubota, Y., Kuzmin, V., Kuznetsov, M., Kwon, Y. J., Lee, K. H., Lubsandorzhiev, B., Lundquist, J. P., Matsumiya, H., Matsuyama, T., Matthews, J. N., Mayta, R., Myers, I., Nagataki, S., Nakai, K., Nakamura, R., Nakamura, T., Nakamura, Y., Nakazawa, A., Nishio, E., Nonaka, T., Oda, H., Ogio, S., Ohnishi, M., Ohoka, H., Oku, Y., Okuda, T., Omura, Y., Ono, M., Oshima, A., Ozawa, S., Park, I. H., Potts, M., Pshirkov, M. S., Rodriguez, D. C., Rott, C., Rubtsov, G. I., Ryu, D., Sagawa, H., Sakaki, N., Sako, T., Sakurai, N., Sato, K., Seki, T., Sekino, K., Shah, P. D., Shibasaki, Y., Shibata, N., Shibata, T., Shikita, J., Shimodaira, H., Shin, B. K., Shin, H. S., Shinto, D., Smith, J. D., Sokolsky, P., Stokes, B. T., Stroman, T. A., Takahashi, K., Takamura, M., Takeda, M., Takeishi, R., Taketa, A., Takita, M., Tameda, Y., Tanaka, K., Tanaka, M., Tanoue, Y., Thomas, S. B., Thomson, G. B., Tinyakov, P., Tkachev, I., Tokuno, H., Tomida, T., Troitsky, S., Tsuda, R., Tsunesada, Y., Udo, S., Uehama, T., Urban, F., Warren, D., Wong, T., Yamamoto, M., Yamazaki, K., Yashiro, K., Yoshida, F., Zhezher, Y., and Zundel, Z.

Subjects
Physics - Atmospheric and Oceanic Physics, Astrophysics - Instrumentation and Methods for Astrophysics, High Energy Physics - Experiment
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
2022
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17. 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

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

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

The relative abundance of cosmic ray nickel nuclei with respect to iron is by far larger than for all other trans-iron elements, therefore it provides a favorable 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 cosmic ray source and to model the Galactic propagation of heavy nuclei. However, only a few direct measurements of cosmic-ray nickel at energy larger than $ \sim$ 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 in the energy range from 8.8 to 240 GeV/n, carried out with unprecedented precision by the Calorimetric Electron 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 [O. Adriani et al., Phys. Rev. Lett. 126, 241101 (2021).], 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 to 240 GeV$ /n $ our present data are compatible within the errors with a single power law with spectral index $ -2.51 \pm 0.07 $., Comment: main text: 8 pages, 4 figures; supplemental material: 8 pages, 9 figures, 1 table. arXiv admin note: text overlap with arXiv:2106.08036

Published
2022
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18. The Calorimetric Electron Telescope (CALET) on the International Space Station: Results from the first eight years on orbit

Author

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

Published
2024
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19. Direct measurements of cosmic – Ray iron and nickel with CALET on the International Space Station

Author

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

Published
2024
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20. Search for Spatial Correlations of Neutrinos with Ultra-High-Energy Cosmic Rays

Author

The ANTARES collaboration, Albert, A., Alves, S., André, M., Anghinolfi, M., Ardid, M., Ardid, S., Aubert, J. -J., Aublin, J., Baret, B., Basa, S., Belhorma, B., Bendahman, M., Bertin, V., Biagi, S., Bissinger, M., Boumaaza, J., Bouta, M., Bouwhuis, M. C., Brânzaş, H., Bruijn, R., Brunner, J., Busto, J., Caiffi, B., Calvo, D., Capone, A., Caramete, L., Carr, J., Carretero, V., Celli, S., Chabab, M., Chau, T. N., Moursli, R. Cherkaoui El, Chiarusi, T., Circella, M., Coleiro, A., Coniglione, R., Coyle, P., Creusot, A., Díaz, A. F., Distefano, C., Di Palma, I., Domi, A., Donzaud, C., Dornic, D., Drouhin, D., Eberl, T., van Eeden, T., van Eijk, D., Khayati, N. El, Enzenhöfer, A., Fermani, P., Ferrara, G., Filippini, F., Fusco, L., Gatelet, Y., Gay, P., Glotin, H., Gozzini, R., Ruiz, R. Gracia, Graf, K., Guidi, C., Hallmann, S., van Haren, H., Heijboer, A. J., Hello, Y., Hernández-Rey, J. J., Hößl, J., Hofestädt, J., Huang, F., Illuminati, G., James, C. W., Jisse-Jung, B., de Jong, M., de Jong, P., Kadler, M., Kalekin, O., Katz, U., Khan-Chowdhury, N. R., Kouchner, A., Kreykenbohm, I., Kulikovskiy, V., Lahmann, R., Breton, R. Le, LeStum, S., Lefèvre, D., Leonora, E., Levi, G., Lopez-Coto, D., Loucatos, S., Maderer, L., Manczak, J., Marcelin, M., Margiotta, A., Marinelli, A., Martínez-Mora, J. A., Martino, B., Melis, K., Migliozzi, P., Moussa, A., Muller, R., Nauta, L., Navas, S., Nezri, E., Fearraigh, B. Ó, Păun, A., Păvălaş, G. E., Pellegrino, C., Perrin-Terrin, M., Pestel, V., Piattelli, P., Pieterse, C., Poirè, C., Popa, V., Pradier, T., Randazzo, N., Real, D., Reck, S., Riccobene, G., Romanov, A., Sánchez-Losa, A., Greus, F. Salesa, Samtleben, D. F. E., Sanguineti, M., Sapienza, P., Schnabel, J., Schumann, J., Schüssler, F., Seneca, J., Spurio, M., Stolarczyk, Th., Taiuti, M., Tayalati, Y., Tingay, S. J., Vallage, B., Van Elewyck, V., Versari, F., Viola, S., Vivolo, D., Wilms, J., Zavatarelli, S., Zegarelli, A., Zornoza, J. D., Zúñiga, J., collaboration, The IceCube, Abbasi, R., Ackermann, M., Adams, J., Aguilar, J. A., Ahlers, M., Ahrens, M., Alameddine, J. M., Alispach, C., Alves Jr., A. A., Amin, N. M., Andeen, K., Anderson, T., Anton, G., Argüelles, C., Ashida, Y., Axani, S., Bai, X., V., A. Balagopal, Barbano, A., Barwick, S. W., Bastian, B., Basu, V., Baur, S., Bay, R., Beatty, J. J., Becker, K. -H., Tjus, J. Becker, Bellenghi, C., BenZvi, S., Berley, D., Bernardini, E., Besson, D. Z., Binder, G., Bindig, D., Blaufuss, E., Blot, S., Boddenberg, M., Bontempo, F., Borowka, J., Böser, S., Botner, O., Böttcher, J., Bourbeau, E., Bradascio, F., Braun, J., Brinson, B., Bron, S., Brostean-Kaiser, J., Browne, S., Burgman, A., Burley, R. T., Busse, R. S., Campana, M. A., Carnie-Bronca, E. G., Chen, C., Chen, Z., Chirkin, D., Choi, K., Clark, B. A., Clark, K., Classen, L., Collin, G. H., Conrad, J. M., Coppin, P., Correa, P., Cowen, D. F., Cross, R., Dappen, C., Dave, P., De Clercq, C., DeLaunay, J. J., López, D. Delgado, Dembinski, H., Deoskar, K., Desai, A., Desiati, P., de Vries, K. D., de Wasseige, G., de With, M., DeYoung, T., Diaz, A., Díaz-Vélez, J. C., Dittmer, M., Dujmovic, H., Dunkman, M., DuVernois, M. A., Dvorak, E., Ehrhardt, T., Eller, P., Erpenbeck, H., Evans, J., Evenson, P. A., Fan, K. L., Fazely, A. R., Fedynitch, A., Feigl, N., Fiedlschuster, S., Fienberg, A. T., Filimonov, K., Finley, C., Fischer, L., Fox, D., Franckowiak, A., Friedman, E., Fritz, A., Fürst, P., Gaisser, T. K., Gallagher, J., Ganster, E., Garcia, A., Garrappa, S., Gerhardt, L., Ghadimi, A., Glaser, C., Glauch, T., Glüsenkamp, T., Gonzalez, J. G., Goswami, S., Grant, D., Grégoire, T., Griswold, S., Günther, C., Gutjahr, P., Haack, C., Hallgren, A., Halliday, R., Halve, L., Halzen, F., Minh, M. Ha, Hanson, K., Hardin, J., Harnisch, A. A., Haungs, A., Hebecker, D., Helbing, K., Henningsen, F., Hettinger, E. C., Hickford, S., Hignight, J., Hill, C., Hill, G. C., Hoffman, K. D., Hoffmann, R., Hokanson-Fasig, B., Hoshina, K., Huber, M., Huber, T., Hultqvist, K., Hünnefeld, M., Hussain, R., Hymon, K., In, S., Iovine, N., Ishihara, A., Jansson, M., Japaridze, G. S., Jeong, M., Jin, M., Jones, B. J. P., Kang, D., Kang, W., Kang, X., Kappes, A., Kappesser, D., Kardum, L., Karg, T., Karl, M., Karle, A., Kauer, M., Kellermann, M., Kelley, J. L., Kheirandish, A., Kin, K., Kintscher, T., Kiryluk, J., Klein, S. R., Koirala, R., Kolanoski, H., Kontrimas, T., Köpke, L., Kopper, C., Kopper, S., Koskinen, D. J., Koundal, P., Kovacevich, M., Kowalski, M., Kozynets, T., Kun, E., Kurahashi, N., Lad, N., Gualda, C. Lagunas, Lanfranchi, J. L., Larson, M. J., Lauber, F., Lazar, J. P., Lee, J. W., Leonard, K., Leszczyńska, A., Li, Y., Lincetto, M., Liu, Q. R., Liubarska, M., Lohfink, E., Mariscal, C. J. Lozano, Lucarelli, F., Ludwig, A., Luszczak, W., Lyu, Y., Ma, W. Y., Madsen, J., Mahn, K. B. M., Makino, Y., Mancina, S., Martinez-Soler, I., Maruyama, R., Mase, K., McElroy, T., McNally, F., Mead, J. V., Meagher, K., Mechbal, S., Medina, A., Meier, M., Meighen-Berger, S., Micallef, J., Mockler, D., Montaruli, T., Moore, R. W., Morse, R., Moulai, M., Naab, R., Nagai, R., Naumann, U., Necker, J., Nguyên, L. V., Niederhausen, H., Nisa, M. U., Nowicki, S. C., Pollmann, A. Obertacke, Oehler, M., Oeyen, B., Olivas, A., O'Sullivan, E., Pandya, H., Pankova, D. V., Park, N., Parker, G. K., Paudel, E. N., Paul, L., Heros, C. Pérez de los, Peters, L., Peterson, J., Philippen, S., Pieper, S., Pittermann, M., Pizzuto, A., Plum, M., Popovych, Y., Porcelli, A., Rodriguez, M. Prado, Price, P. B., Pries, B., Przybylski, G. T., Raab, C., Rack-Helleis, J., Raissi, A., Rameez, M., Rawlins, K., Rea, I. C., Rehman, A., Reichherzer, P., Reimann, R., Renzi, G., Resconi, E., Reusch, S., Rhode, W., Richman, M., Riedel, B., Roberts, E. J., Robertson, S., Roellinghoff, G., Rongen, M., Rott, C., Ruhe, T., Ryckbosch, D., Cantu, D. Rysewyk, Safa, I., Saffer, J., Herrera, S. E. Sanchez, Sandrock, A., Santander, M., Sarkar, S., Satalecka, K., Schaufel, M., Schindler, S., Schmidt, T., Schneider, A., Schneider, J., Schröder, F. G., Schumacher, L., Schwefer, G., Sclafani, S., Seckel, D., Seunarine, S., Sharma, A., Shefali, S., Silva, M., Skrzypek, B., Smithers, B., Snihur, R., Soedingrekso, J., Soldin, D., Spannfellner, C., Spiczak, G. M., Spiering, C., Stachurska, J., Stamatikos, M., Stanev, T., Stein, R., Stettner, J., Steuer, A., Stezelberger, T., Stürwald, T., Stuttard, T., Sullivan, G. W., Taboada, I., Ter-Antonyan, S., Tilav, S., Tischbein, F., Tollefson, K., Tönnis, C., Toscano, S., Tosi, D., Trettin, A., Tselengidou, M., Tung, C. F., Turcati, A., Turcotte, R., Turley, C. F., Twagirayezu, J. P., Ty, B., Elorrieta, M. A. Unland, Valtonen-Mattila, N., Vandenbroucke, J., van Eijndhoven, N., Vannerom, D., van Santen, J., Verpoest, S., Walck, C., Watson, T. B., Weaver, C., Weigel, P., Weindl, A., Weiss, M. J., Weldert, J., Wendt, C., Werthebach, J., Weyrauch, M., Whitehorn, N., Wiebusch, C. H., Williams, D. R., Wolf, M., Woschnagg, K., Wrede, G., Wulff, J., Xu, X. W., Yanez, J. P., Yoshida, S., Yu, S., Yuan, T., Zhang, Z., Zhelnin, P., collaboration, The Pierre Auger, Abreu, P., Aglietta, M., Albury, J. M., Allekotte, I., Cheminant, K. Almeida, Almela, A., Alvarez-Muñiz, J., Batista, R. Alves, Anastasi, G. A., Anchordoqui, L., Andrada, B., Andringa, S., Aramo, C., Ferreira, P. R. Araújo, Arnone, E., Velázquez, J. C. Arteaga, Asorey, H., Assis, P., Avila, G., Badescu, A. M., Bakalova, A., Balaceanu, A., Barbato, F., Bellido, J. A., Berat, C., Bertaina, M. E., Bertou, X., Bhatta, G., Biermann, P. L., Binet, V., Bismark, K., Bister, T., Biteau, J., Blazek, J., Bleve, C., Blümer, J., Boháčová, M., Boncioli, D., Bonifazi, C., Arbeletche, L. Bonneau, Borodai, N., Botti, A. M., Brack, J., Bretz, T., Orchera, P. G. Brichetto, Briechle, F. L., Buchholz, P., Bueno, A., Buitink, S., Buscemi, M., Büsken, M., Caballero-Mora, K. S., Caccianiga, L., Canfora, F., Caracas, I., Caruso, R., Castellina, A., Catalani, F., Cataldi, G., Cazon, L., Cerda, M., Chinellato, J. A., Chudoba, J., Chytka, L., Clay, R. W., Cerutti, A. C. Cobos, Colalillo, R., Coleman, A., Coluccia, M. R., Conceição, R., Condorelli, A., Consolati, G., Contreras, F., Convenga, F., Santos, D. Correia dos, Covault, C. E., Dasso, S., Daumiller, K., Dawson, B. R., Day, J. A., de Almeida, R. M., de Jesús, J., de Jong, S. J., Neto, J. R. T. de Mello, De Mitri, I., de Oliveira, J., Franco, D. de Oliveira, de Palma, F., de Souza, V., De Vito, E., Del Popolo, A., del Río, M., Deligny, O., Deval, L., di Matteo, A., Dobre, M., Dobrigkeit, C., D'Olivo, J. C., Mendes, L. M. Domingues, Anjos, R. C. dos, Dova, M. T., Ebr, J., Engel, R., Epicoco, I., Erdmann, M., Escobar, C. O., Etchegoyen, A., Falcke, H., Farmer, J., Farrar, G., Fauth, A. C., Fazzini, N., Feldbusch, F., Fenu, F., Fick, B., Figueira, J. M., Filipčič, A., Fitoussi, T., Fodran, T., Fujii, T., Fuster, A., Galea, C., Galelli, C., García, B., Vegas, A. L. Garcia, Gemmeke, H., Gesualdi, F., Gherghel-Lascu, A., Ghia, P. L., Giaccari, U., Giammarchi, M., Glombitza, J., Gobbi, F., Gollan, F., Golup, G., Berisso, M. Gómez, Vitale, P. F. Gómez, Gongora, J. P., González, J. M., González, N., Goos, I., Góra, D., Gorgi, A., Gottowik, M., Grubb, T. D., Guarino, F., Guedes, G. P., Guido, E., Hahn, S., Hamal, P., Hampel, M. R., Hansen, P., Harari, D., Harvey, V. M., Hebbeker, T., Heck, D., Hojvat, C., Hörandel, J. R., Horvath, P., Hrabovský, M., Huege, T., Insolia, A., Isar, P. G., Janecek, P., Johnsen, J. A., Jurysek, J., Kääpä, A., Kampert, K. H., Karastathis, N., Keilhauer, B., Khakurdikar, A., Covilakam, V. V. Kizakke, Klages, H. O., Kleifges, M., Kleinfeller, J., Knapp, F., Kunka, N., Lago, B. L., Lang, R. G., Langner, N., de Oliveira, M. A. Leigui, Lenok, V., Letessier-Selvon, A., Lhenry-Yvon, I., Presti, D. Lo, Lopes, L., López, R., Lu, L., Luce, Q., Lundquist, J. P., Payeras, A. Machado, Mancarella, G., Mandat, D., Manning, B. C., Manshanden, J., Mantsch, P., Marafico, S., Mariani, F. M., Mariazzi, A. G., Mariş, I. C., Marsella, G., Martello, D., Martinelli, S., Bravo, O. Martínez, Mastrodicasa, M., Mathes, H. J., Matthews, J., Matthiae, G., Mayotte, E., Mayotte, S., Mazur, P. O., Medina-Tanco, G., Melo, D., Menshikov, A., Michal, S., Micheletti, M. I., Miramonti, L., Mollerach, S., Montanet, F., Morejon, L., Morello, C., Mostafá, M., Müller, A. L., Muller, M. A., Mulrey, K., Mussa, R., Muzio, M., Namasaka, W. M., Nasr-Esfahani, A., Nellen, L., Nicora, G., Niculescu-Oglinzanu, M., Niechciol, M., Nitz, D., Nosek, D., Novotny, V., Nožka, L., Nucita, A., Núñez, L. A., Oliveira, C., Palatka, M., Pallotta, J., Papenbreer, P., Parente, G., Parra, A., Pawlowsky, J., Pech, M., Pȩkala, J., Pelayo, R., Peña-Rodriguez, J., Martins, E. E. Pereira, Armand, J. Perez, Bertolli, C. Pérez, Perlin, M., Perrone, L., Petrera, S., Petrucci, C., Pierog, T., Pimenta, M., Pirronello, V., Platino, M., Pont, B., Pothast, M., Privitera, P., Prouza, M., Puyleart, A., Querchfeld, S., Rautenberg, J., Ravignani, D., Reininghaus, M., Ridky, J., Riehn, F., Risse, M., Rizi, V., de Carvalho, W. Rodrigues, Rojo, J. Rodriguez, Roncoroni, M. J., Rossoni, S., Roth, M., Roulet, E., Rovero, A. C., Ruehl, P., Saftoiu, A., Saharan, M., Salamida, F., Salazar, H., Salina, G., Gomez, J. D. Sanabria, Sánchez, F., Santos, E. M., Santos, E., Sarazin, F., Sarmento, R., Sarmiento-Cano, C., Sato, R., Savina, P., Schäfer, C. M., Scherini, V., Schieler, H., Schimassek, M., Schimp, M., Schlüter, F., Schmidt, D., Scholten, O., Schoorlemmer, H., Schovánek, P., Schulte, J., Schulz, T., Sciutto, S. J., Scornavacche, M., Segreto, A., Sehgal, S., Shellard, R. C., Sigl, G., Silli, G., Sima, O., Smau, R., Šmída, R., Sommers, P., Soriano, J. F., Squartini, R., Stadelmaier, M., Stanca, D., Stanič, S., Stasielak, J., Stassi, P., Streich, A., Suárez-Durán, M., Sudholz, T., Suomijärvi, T., Supanitsky, A. D., Szadkowski, Z., Tapia, A., Taricco, C., Timmermans, C., Tkachenko, O., Tobiska, P., Peixoto, C. J. Todero, Tomé, B., Torrès, Z., Travaini, A., Travnicek, P., Trimarelli, C., Tueros, M., Ulrich, R., Unger, M., Vaclavek, L., Vacula, M., Galicia, J. F. Valdés, Valore, L., Varela, E., Vásquez-Ramírez, A., Veberič, D., Ventura, C., Quispe, I. D. Vergara, Verzi, V., Vicha, J., Vink, J., Vorobiov, S., Wahlberg, H., Watanabe, C., Watson, A. A., Wiencke, L., Wilczyński, H., Wittkowski, D., Wundheiler, B., Yushkov, A., Zapparrata, O., Zas, E., Zavrtanik, D., Zavrtanik, M., Zehrer, L., collaboration, The Telescope Array, Abu-Zayyad, T., Allen, M., Arai, Y., Arimura, R., Barcikowski, E., Belz, J. W., Bergman, D. R., Blake, S. A., Buckland, I., Cady, R., Cheon, B. G., Chiba, J., Chikawa, M., Fujisue, K., Fujita, K., Fujiwara, R., Fukushima, M., Fukushima, R., Furlich, G., Globus, N., Gonzalez, R., Hanlon, W., Hayashi, M., Hayashida, N., He, H., Hibino, K., Higuchi, R., Honda, K., Ikeda, D., Inadomi, T., Inoue, N., Ishii, T., Ito, H., Ivanov, D., Iwakura, H., Iwasaki, A., Jeong, H. M., Jeong, S., Jui, C. C. H., Kadota, K., Kakimoto, F., Kalashev, O., Kasahara, K., Kasami, S., Kawakami, S., Kawana, S., Kawata, K., Kharuk, I., Kido, E., Kim, H. B., Kim, J. H., Kim, S. W., Kimura, Y., Kishigami, S., Kubota, Y., Kurisu, S., Kuzmin, V., Kuznetsov, M., Kwon, Y. J., Lee, K. H., Lubsandorzhiev, B., Machida, K., Matsumiya, H., Matsuyama, T., Matthews, J. N., Mayta, R., Minamino, M., Mukai, K., Myers, I., Nagataki, S., Nakai, K., Nakamura, R., Nakamura, T., Nakamura, Y., Nakazawa, A., Nishio, E., Nonaka, T., Oda, H., Ogio, S., Ohnishi, M., Ohoka, H., Oku, Y., Okuda, T., Omura, Y., Ono, M., Onogi, R., Oshima, A., Ozawa, S., Park, I. H., Potts, M., Pshirkov, M. S., Remington, J., Rodriguez, D. C., Rubtsov, G. I., Ryu, D., Sagawa, H., Sahara, R., Saito, Y., Sakaki, N., Sako, T., Sakurai, N., Sano, K., Sato, K., Seki, T., Sekino, K., Shah, P. D., Shibasaki, Y., Shibata, F., Shibata, N., Shibata, T., Shimodaira, H., Shin, B. K., Shin, H. S., Shinto, D., Smith, J. D., Sokolsky, P., Sone, N., Stokes, B. T., Stroman, T. A., Takagi, Y., Takahashi, Y., Takamura, M., Takeda, M., Takeishi, R., Taketa, A., Takita, M., Tameda, Y., Tanaka, H., Tanaka, K., Tanaka, M., Tanoue, Y., Thomas, S. B., Thomson, G. B., Tinyakov, P., Tkachev, I., Tokuno, H., Tomida, T., Troitsky, S., Tsuda, R., Tsunesada, Y., Uchihori, Y., Udo, S., Uehama, T., Urban, F., Warren, D., Wong, T., Yamamoto, M., Yamazaki, K., Yashiro, K., Yoshida, F., Yoshioka, Y., Zhezher, Y., and Zundel, Z.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

For several decades, the origin of ultra-high-energy cosmic rays (UHECRs) has been an unsolved question of high-energy astrophysics. One approach for solving this puzzle is to correlate UHECRs with high-energy neutrinos, since neutrinos are a direct probe of hadronic interactions of cosmic rays and are not deflected by magnetic fields. In this paper, we present three different approaches for correlating the arrival directions of neutrinos with the arrival directions of UHECRs. The neutrino data is provided by the IceCube Neutrino Observatory and ANTARES, while the UHECR data with energies above $\sim$50 EeV is provided by the Pierre Auger Observatory and the Telescope Array. All experiments provide increased statistics and improved reconstructions with respect to our previous results reported in 2015. The first analysis uses a high-statistics neutrino sample optimized for point-source searches to search for excesses of neutrinos clustering in the vicinity of UHECR directions. The second analysis searches for an excess of UHECRs in the direction of the highest-energy neutrinos. The third analysis searches for an excess of pairs of UHECRs and highest-energy neutrinos on different angular scales. None of the analyses has found a significant excess, and previously reported over-fluctuations are reduced in significance. Based on these results, we further constrain the neutrino flux spatially correlated with UHECRs., Comment: 39 pages, 7 figures, 4 tables; updated source files including xml authorlist

Published
2022
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21. Observation of Variations in Cosmic Ray Single Count Rates During Thunderstorms and Implications for Large-Scale Electric Field Changes

Author

Abbasi, R. U., Abu-Zayyad, T., Allen, M., Arai, Y., Arimura, R., Barcikowski, E., Belz, J. W., Bergman, D. R., Blake, S. A., Buckland, I., Cady, R., Cheon, B. G., Chiba, J., Chikawa, M., Fujii, T., Fujisue, K., Fujita, K., Fujiwara, R., Fukushima, M., Fukushima, R., Furlich, G., Globus, N., Gonzalez, R., Hanlon, W., Hayashi, M., Hayashida, N., Hibino, K., Higuchi, R., Honda, K., Husseini, N., Ikeda, D., Inadomi, T., Inoue, N., Ishii, T., Ito, H., Ivanov, D., Iwakura, H., Iwasaki, A., Jeong, H. M., Jeong, S., Johnson, H., Jui, C. C. H., Kadota, K., Kakimoto, F., Kalashev, O., Kasahara, K., Kasami, S., Kawai, H., Kawakami, S., Kawana, S., Kawata, K., Kharuk, I., Kido, E., Kim, H. B., Kim, J. H., Kim, M. H., Kim, S. W., Kimura, Y., Kishigami, S., Kubota, Y., Kurisu, S., Kuzmin, V., Kuznetsov, M., Kwon, Y. J., Lee, K. H., LeVon, R., Lubsandorzhiev, B., Lundquist, J. P., Machida, K., Matsumiya, H., Matsuyama, T., Matthews, J. N., Mayta, R., Mazich, J., Minamino, M., Mukai, K., Myers, I., Myers, P., Nagataki, S., Nakai, K., Nakamura, R., Nakamura, T., Nakamura, Y., Nakazawa, A., Nishio, E., Nonaka, T., OBrien, K., Oda, H., Ogio, S., Ohnishi, M., Ohoka, H., Oku, Y., Okuda, T., Omura, Y., Ono, M., Onogi, R., Oshima, A., Ozawa, S., Park, I. H., Potts, M., Pshirkov, M. S., Remington, J., Rodriguez, D. C., Rubtsov, G. I., Ryu, D., Sagawa, H., Sahara, R., Saito, Y., Sakaki, N., Sako, T., Sakurai, N., Sano, K., Sato, K., Seki, T., Sekino, K., Shah, P. D., Shibasaki, Y., Shibata, F., Shibata, N., Shibata, T., Shimodaira, H., Shin, B. K., Shin, H. S., Shinto, D., Smith, J. D., Sokolsky, P., Sone, N., Stokes, B. T., Stroman, T. A., Takagi, Y., Takahashi, Y., Takamura, M., Takeda, M., Takeishi, R., Taketa, A., Takita, M., Tameda, Y., Tanaka, H., Tanaka, K., Tanaka, M., Tanoue, Y., Thomas, S. B., Thomson, G. B., Tinyakov, P., Tkachev, I., Tokuno, H., Tomida, T., Troitsky, S., Tsuda, R., Tsunesada, Y., Uchihori, Y., Udo, S., Uehama, T., Urban, F., Wong, T., Yamamoto, M., Yamazaki, K., Yang, J., Yashiro, K., Yoshida, F., Yoshioka, Y., Zhezher, Y., and Zundel, Z.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, High Energy Physics - Experiment, Physics - Atmospheric and Oceanic Physics
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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22. Indications of a Cosmic Ray Source in the Perseus-Pisces Supercluster

Author

Telescope Array Collaboration, Abbasi, R. U., Abu-Zayyad, T., Allen, M., Arai, Y., Arimura, R., Barcikowski, E., Belz, J. W., Bergman, D. R., Blake, S. A., Buckland, I., Cady, R., Cheon, B. G., Chiba, J., Chikawa, M., Fujii, T., Fujisue, K., Fujita, K., Fujiwara, R., Fukushima, M., Fukushima, R., Furlich, G., Globus, N., Gonzalez, R., Hanlon, W., Hayashi, M., Hayashida, N., Hibino, K., Higuchi, R., Honda, K., Ikeda, D., Inadomi, T., Inoue, N., Ishii, T., Ito, H., Ivanov, D., Iwakura, H., Iwasaki, A., Jeong, H. M., Jeong, S., Jui, C. C. H., Kadota, K., Kakimoto, F., Kalashev, O., Kasahara, K., Kasami, S., Kawai, H., Kawakami, S., Kawana, S., Kawata, K., Kharuk, I., Kido, E., Kim, H. B., Kim, J. H., Kim, M. H., Kim, S. W., Kimura, Y., Kishigami, S., Kubota, Y., Kurisu, S., Kuzmin, V., Kuznetsov, M., Kwon, Y. J., Lee, K. H., Lubsandorzhiev, B., Lundquist, J. P., Machida, K., Matsumiya, H., Matsuyama, T., Matthews, J. N., Mayta, R., Minamino, M., Mukai, K., Myers, I., Nagataki, S., Nakai, K., Nakamura, R., Nakamura, T., Nakamura, Y., Nakazawa, A., Nishio, E., Nonaka, T., Oda, H., Ogio, S., Ohnishi, M., Ohoka, H., Oku, Y., Okuda, T., Omura, Y., Ono, M., Onogi, R., Oshima, A., Ozawa, S., Park, I. H., Potts, M., Pshirkov, M. S., Remington, J., Rodriguez, D. C., Rubtsov, G. I., Ryu, D., Sagawa, H., Sahara, R., Saito, Y., Sakaki, N., Sako, T., Sakurai, N., Sano, K., Sato, K., Seki, T., Sekino, K., Shah, P. D., Shibasaki, Y., Shibata, F., Shibata, N., Shibata, T., Shimodaira, H., Shin, B. K., Shin, H. S., Shinto, D., Smith, J. D., Sokolsky, P., Sone, N., Stokes, B. T., Stroman, T. A., Takagi, Y., Takahashi, Y., Takamura, M., Takeda, M., Takeishi, R., Taketa, A., Takita, M., Tameda, Y., Tanaka, H., Tanaka, K., Tanaka, M., Tanoue, Y., Thomas, S. B., Thomson, G. B., Tinyakov, P., Tkachev, I., Tokuno, H., Tomida, T., Troitsky, S., Tsuda, R., Tsunesada, Y., Uchihori, Y., Udo, S., Uehama, T., Urban, F., Wong, T., Yamamoto, M., Yamazaki, K., Yang, J., Yashiro, K., Yoshida, F., Yoshioka, Y., Zhezher, Y., and Zundel, Z.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

The Telescope Array Collaboration has observed an excess of events with $E \ge 10^{19.4} ~{\rm eV}$ in the data which is centered at (RA, dec) = ($19^\circ$, $35^\circ$). This is near the center of the Perseus-Pisces supercluster (PPSC). The PPSC is about $70 ~{\rm Mpc}$ distant and is the closest supercluster in the Northern Hemisphere (other than the Virgo supercluster of which we are a part). A Li-Ma oversampling analysis with $20^\circ$-radius circles indicates an excess in the arrival direction of events with a local significance of about 4 standard deviations. The probability of having such excess close to the PPSC by chance is estimated to be 3.5 standard deviations. This result indicates that a cosmic ray source likely exists in that supercluster., Comment: 8 pages, 4 figures, 1 table

Published
2021

23. Detectability of southern gamma-ray sources beyond 100 TeV with ALPAQUITA, the prototype experiment of ALPACA

Author

Kato, S., Condori, C. A. H., Fuente, E. dela, Gomi, A., Hibino, K., Hotta, N., Toledano-Juarez, I., Katayose, Y., Kato, C., Kawata, K., Kihara, W., Ko, Y., Koi, T., Kojima, H., Kurashige, D., Lozoya, J., Orozco-Luna, F., Mayta, R., Miranda, P., Munakata, K., Nakada, H., Nakamura, Y., Nakazawa, Y., Nina, C., Nishizawa, M., Ogio, S., Ohnishi, M., Ohura, T., Okukawa, S., Oshima, A., Raljevich, M., Rivera, H., Saito, T., Sako, T., Sako, T. K., Shibata, S., Shiomi, A., Subieta, M., Tajima, N., Takano, W., Takita, M., Tameda, Y., Tanaka, K., Ticona, R., Torres, H., Tsuchiya, H., Tsunesada, Y., Udo, S., Yamazaki, K., and Yokoe, Y.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics
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., Comment: This is the manuscript accepted by Experimental Astronomy. For the published article, see https://doi.org/10.1007/s10686-021-09796-8

Published
2021
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24. Potential PeVatron supernova remnant G106.3+2.7 seen in the highest-energy gamma rays

Author

Amenomori, M., Bao, Y. W., Bi, X. J., Chen, D., Chen, T. L., Chen, W. Y., Chen, Xu, Chen, Y., Cirennima, Cui, S. W., Danzengluobu, Ding, L. K., Fang, J. H., Fang, K., Feng, C. F., Feng, Zhaoyang, Feng, Z. Y., Gao, Qi, Gou, Q. B., Guo, Y. Q., Guo, Y. Y., He, H. H., He, Z. T., Hibino, K., Hotta, N., Hu, Haibing, Hu, H. B., Huang, J., Jia, H. Y., Jiang, L., Jin, H. B., Kasahara, K., Katayose, Y., Kato, C., Kato, S., Kawata, K., Kihara, W., Ko, Y., Kozai, M., Labaciren, Le, G. M., Li, A. F., Li, H. J., Li, W. J., Lin, Y. H., Liu, B., Liu, C., Liu, J. S., Liu, M. Y., Liu, W., Lou, Y. -Q., Lu, H., Meng, X. R., Munakata, K., Nakada, H., Nakamura, Y., Nanjo, H., Nishizawa, M., Ohnishi, M., Ohura, T., Ozawa, S., Qian, X. L., Qu, X. B., Saito, T., Sakata, M., Sako, T. K., Shao, J., Shibata, M., Shiomi, A., Sugimoto, H., Takano, W., Takita, M., Tan, Y. H., Tateyama, N., Torii, S., Tsuchiya, H., Udo, S., Wang, H., Wu, H. R., Xue, L., Yamamoto, Y., Yang, Z., Yokoe, Y., Yuan, A. F., Zhai, L. M., Zhang, H. M., Zhang, J. L., Zhang, X., Zhang, X. Y., Zhang, Y., Zhang, Yi, Zhang, Ying, Zhao, S. P., Zhaxisangzhu, and Zhou, X. X.

Subjects
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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25. Gamma-ray Observation of the Cygnus Region in the 100 TeV Energy Region

Author

Amenomori, M., Bao, Y. W., Bi, X. J., Chen, D., Chen, T. L., Chen, W. Y., Chen, Xu, Chen, Y., Cirennima, Cui, S. W., Danzengluobu, Ding, L. K., Fang, J. H., Fang, K., Feng, C. F., Feng, Zhaoyang, Feng, Z. Y., Gao, Qi, Gomi, A., Gou, Q. B., Guo, Y. Q., Guo, Y. Y., He, H. H., He, Z. T., Hibino, K., Hotta, N., Hu, Haibing, Hu, H. B., Huang, J., Jia, H. Y., Jiang, L., Jiang, P., Jin, H. B., Kasahara, K., Katayose, Y., Kato, C., Kato, S., Kawata, K., Kozai, M., Kurashige, D., Labaciren, Le, G. M., Li, A. F., Li, H. J., Li, W. J., Li, Y., Lin, Y. H., Liu, B., Liu, C., Liu, J. S., Liu, L. Y., Liu, M. Y., Liu, W., Liu, X. L., Lou, Y. -Q., Lu, H., Meng, X. R., Munakata, K., Nakada, H., Nakamura, Y., Nakazawa, Y., Nanjo, H., Ning, C. C., Nishizawa, M., Ohnishi, M., Ohura, T., Okukawa, S., Ozawa, S., Qian, L., Qian, X., Qian, X. L., Qu, X. B., Saito, T., Sakata, M., Sako, T., Sako, T. K., Shao, J., Shibata, M., Shiomi, A., Sugimoto, H., Takano, W., Takita, M., Tan, Y. H., Tateyama, N., Torii, S., Tsuchiya, H., Udo, S., Wang, H., Wang, Y. P., Wangdui, Wu, H. R., Wu, Q., Xu, J. L., Xue, L., Yamamoto, Y., Yang, Z., Yao, Y. Q., Yin, J., Yokoe, Y., Yu, N. P., Yuan, A. F., Zhai, L. M., Zhang, C. P., Zhang, H. M., Zhang, J. L., Zhang, X., Zhang, X. Y., Zhang, Y., Zhang, Yi, Zhang, Ying, Zhao, S. P., Zhaxisangzhu, and Zhou, X. X.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
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., Comment: Accepted for publication in the Physical Review Letters

Published
2021
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26. 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

Adriani, O., Akaike, Y., Asano, K., Asaoka, Y., Berti, E., Bigongiari, G., Binns, W. R., Bongi, M., Brogi, P., Bruno, A., Buckley, J. H., Cannady, N., Castellini, G., Checchia, C., Cherry, M. L., Collazuol, G., Ebisawa, K., Fuke, H., Gonzi, S., Guzik, T. G., Hams, T., Hibino, K., Ichimura, M., Ioka, K., Ishizaki, W., Israel, M. H., Kasahara, K., Kataoka, J., Kataoka, R., Katayose, Y., Kato, C., Kawanaka, N., Kawakubo, Y., Kobayashi, K., Kohri, K., Krawczynski, H. S., Krizmanic, J. F., Link, J., Maestro, P., Marrocchesi, P. S., Messineo, A. M., Mitchell, J. W., Miyake, S., Moiseev, A. A., Mori, M., Mori, N., Motz, H. M., Munakata, K., Nakahira, S., Nishimura, J., de Nolfo, G. A., Okuno, S., Ormes, J. F., Ospina, N., Ozawa, S., Pacini, L., Papini, P., Rauch, B. F., Ricciarini, S. B., Sakai, K., Sakamoto, T., Sasaki, M., Shimizu, Y., Shiomi, A., Spillantini, P., Stolzi, F., Sugita, S., Sulaj, A., Takita, M., Tamura, T., Terasawa, T., Torii, S., Tsunesada, Y., Uchihori, Y., Vannuccini, E., Wefel, J. P., Yamaoka, K., Yanagita, S., Yoshida, A., and Yoshida, K.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
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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27. First Detection of sub-PeV Diffuse Gamma Rays from the Galactic Disk: Evidence for Ubiquitous Galactic Cosmic Rays beyond PeV Energies

Author

Amenomori, M., Bao, Y. W., Bi, X. J., Chen, D., Chen, T. L., Chen, W. Y., Chen, Xu, Chen, Y., Cirennima, Cui, S. W., Danzengluobu, Ding, L. K., Fang, J. H., Fang, K., Feng, C. F., Feng, Zhaoyang, Feng, Z. Y., Gao, Qi, Gou, Q. B., Guo, Y. Q., Guo, Y. Y., He, H. H., He, Z. T., Hibino, K., Hotta, N., Hu, Haibing, Hu, H. B., Huang, J., Jia, H. Y., Jiang, L., Jin, H. B., Kasahara, K., Katayose, Y., Kato, C., Kato, S., Kawata, K., Kihara, W., Ko, Y., Kozai, M., Labaciren, Le, G. M., Li, A. F., Li, H. J., Li, W. J., Lin, Y. H., Liu, B., Liu, C., Liu, J. S., Liu, M. Y., Liu, W., Lou, Y. -Q., Lu, H., Meng, X. R., Munakata, K., Nakada, H., Nakamura, Y., Nanjo, H., Nishizawa, M., Ohnishi, M., Ohura, T., Ozawa, S., Qian, X. L., Qu, X. B., Saito, T., Sakata, M., Sako, T. K., Shao, J., Shibata, M., Shiomi, A., Sugimoto, H., Takano, W., Takita, M., Tan, Y. H., Tateyama, N., Torii, S., Tsuchiya, H., Udo, S., Wang, H., Wu, H. R., Xue, L., Yamamoto, Y., Yang, Z., Yokoe, Y., Yuan, A. F., Zhai, L. M., Zhang, H. M., Zhang, J. L., Zhang, X., Zhang, X. Y., Zhang, Y., Zhang, Yi, Zhang, Ying, Zhao, S. P., Zhaxisangzhu, and Zhou, X. X.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
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
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28. Surface detectors of the TAx4 experiment

Author

Telescope Array Collaboration, Abbasi, R. U., Abe, M., Abu-Zayyad, T., Allen, M., Arai, Y., Barcikowski, E., Belz, J. W., Bergman, D. R., Blake, S. A., Cady, R., Cheon, B. G., Chiba, J., Chikawa, M., Fujii, T., Fujisue, K., Fujita, K., Fujiwara, R., Fukushima, M., Fukushima, R., Furlich, G., Hanlon, W., Hayashi, M., Hayashida, N., Hibino, K., Higuchi, R., Honda, K., Ikeda, D., Inadomi, T., Inoue, N., Ishii, T., Ito, H., Ivanov, D., Iwakura, H., Jeong, H. M., Jeong, S., Jui, C. C. H., Kadota, K., Kakimoto, F., Kalashev, O., Kasahara, K., Kasami, S., Kawai, H., Kawakami, S., Kawana, S., Kawata, K., Kido, E., Kim, H. B., Kim, J. H., Kim, M. H., Kim, S. W., Kimura, Y., Kishigami, S., Kuzmin, V., Kuznetsov, M., Kwon, Y. J., Lee, K. H., Lubsandorzhiev, B., Lundquist, J. P., Machida, K., Matsumiya, H., Matsuyama, T., Matthews, J. N., Mayta, R., Minamino, M., Mukai, K., Myers, I., Nagataki, S., Nakai, K., Nakamura, R., Nakamura, T., Nakamura, Y., Nonaka, T., Oda, H., Ogio, S., Ohnishi, M., Ohoka, H., Oku, Y., Okuda, T., Omura, Y., Ono, M., Onogi, R., Oshima, A., Ozawa, S., Park, I. H., Pshirkov, M. S., Remington, J., Rodriguez, D. C., Rubtsov, G. I., Ryu, D., Sagawa, H., Sahara, R., Saito, Y., Sakaki, N., Sako, T., Sakurai, N., Sano, K., Sato, K., Seki, T., Sekino, K., Shah, P. D., Shibata, F., Shibata, N., Shibata, T., Shimodaira, H., Shin, B. K., Shin, H. S., Shinto, D., Smith, J. D., Sokolsky, P., Sone, N., Stokes, B. T., Stroman, T. A., Suzawa, T., Takagi, Y., Takahashi, Y., Takamura, M., Takeda, M., Takeishi, R., Taketa, A., Takita, M., Tameda, Y., Tanaka, H., Tanaka, K., Tanaka, M., Tanoue, Y., Thomas, S. B., Thomson, G. B., Tinyakov, P., Tkachev, I., Tokuno, H., Tomida, T., Troitsky, S., Tsuda, R., Tsunesada, Y., Uchihori, Y., Udo, S., Uehama, T., Urban, F., Wong, T., Yada, K., Yamamoto, M., Yamazaki, K., Yang, J., Yashiro, K., Yoshida, F., Zhezher, Y., and Zundel, Z.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Physics - Instrumentation and Detectors
Abstract

Telescope Array (TA) is the largest ultrahigh energy cosmic-ray (UHECR) observatory in the Northern Hemisphere. It explores the origin of UHECRs by measuring their energy spectrum, arrival-direction distribution, and mass composition using a surface detector (SD) array covering approximately 700 km$^2$ and fluorescence detector (FD) stations. TA has found evidence for a cluster of cosmic rays with energies greater than 57 EeV. In order to confirm this evidence with more data, it is necessary to increase the data collection rate.We have begun building an expansion of TA that we call TAx4. In this paper, we explain the motivation, design, technical features, and expected performance of the TAx4 SD. We also present TAx4's current status and examples of the data that have already been collected., Comment: 26 pages, 17 figures, submitted to Nuclear Inst. and Methods in Physics Research, A

Published
2021
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29. 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

Adriani, O., Akaike, Y., Asano, K., Asaoka, Y., Bagliesi, M. G., Berti, E., Bigongiari, G., Binns, W. R., Bongi, M., Brogi, P., Bruno, A., Buckley, J. H., Cannady, N., Castellini, G., Checchia, C., Cherry, M. L., Collazuol, G., Ebisawa, K., Fuke, H., Gonzi, S., Guzik, T. G., Hams, T., Hibino, K., Ichimura, M., Ioka, K., Ishizaki, W., Israel, M. H., Kasahara, K., Kataoka, J., Kataoka, R., Katayose, Y., Kato, C., Kawanaka, N., Kawakubo, Y., Kobayashi, K., Kohri, K., Krawczynski, H. S., Krizmanic, J. F., Link, J., Maestro, P., Marrocchesi, P. S., Messineo, A. M., Mitchell, J. W., Miyake, S., Moiseev, A. A., Mori, M., Mori, N., Motz, H. M., Munakata, K., Nakahira, S., Nishimura, J., de Nolfo, G. A., Okuno, S., Ormes, J. F., Ospina, N., Ozawa, S., Pacini, L., Palma, F., Papini, P., Rauch, B. F., Ricciarini, S. B., Sakai, K., Sakamoto, T., Sasaki, M., Shimizu, Y., Shiomi, A., Sparvoli, R., Spillantini, P., Stolzi, F., Sugita, S., Suh, J. E., Sulaj, A., Takita, M., Tamura, T., Terasawa, T., Torii, S., Tsunesada, Y., Uchihori, Y., Vannuccini, E., Wefel, J. P., Yamaoka, K., Yanagita, S., Yoshida, A., and Yoshida, K.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
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., Comment: main text: 7 pages, 3 figures; supplemental material: 20 pages, 15 figures, 3 tables

Published
2020
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30. Hadronic interaction model dependence in cosmic Gamma-ray flux estimation using an extensive air shower array with a muon detector

Author

Okukawa, S., Anzorena, M., Asano, S., Condori, C. A. H., de la Fuente, E., Gomi, A., Hibino, K., Hotta, N., Jimenez-Meza, A., Katayose, Y., Kato, C., Kato, S., Kawashima, T., Kawata, K., Koi, T., Kojima, H., Kurashige, D., Lozoya, J., Mayta, R., Miranda, P., Munakata, K., Nagaya, K., Nakamura, Y., Nakazawa, Y., Nina, C., Nishizawa, M., Ogio, S., Ohnishi, M., Oshima, A., Raljevic, M., Rivera, H., Saito, T., Sakakibara, Y., Sako, T., Sako, T. K., Shibata, S., Shiomi, A., Subieta, M., Tajima, N., Takano, W., Takita, M., Tameda, Y., Tanaka, K., Ticona, R., Toledano-Juarez, I., Tsuchiya, H., Tsunesada, Y., Udo, S., Yamazaki, K., and Yokoe, Y.

Published
2023
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31. Observations of the Origin of Downward Terrestrial Gamma-Ray Flashes

Author

Belz, J. W., Krehbiel, P. R., Remington, J., Stanley, M. A., Abbasi, R. U., LeVon, R., Rison, W., Rodeheffer, D., Collaboration, the Telescope Array Scientific, Abu-Zayyad, T., Allen, M., Barcikowski, E., Bergman, D. R., Blake, S. A., Byrne, M., Cady, R., Cheon, B. G., Chikawa, M., di Matteo, A., Fujii, T., Fujita, K., Fujiwara, R., Fukushima, M., Furlich, G., Hanlon, W., Hayashi, M., Hayashi, Y., Hayashida, N., Hibino, K., Honda, K., Ikeda, D., Inadomi, T., Inoue, N., Ishii, T., Ito, H., Ivanov, D., Iwakura, H., Jeong, H. M., Jeong, S., Jui, C. C. H., Kadota, K., Kakimoto, F., Kalashev, O., Kasahara, K., Kasami, S., Kawai, H., Kawakami, S., Kawata, K., Kido, E., Kim, H. B., Kim, J. H., Kuzmin, V., Kuznetsov, M., Kwon, Y. J., Lee, K. H., Lubsandorzhiev, B., Lundquist, J. P., Machida, K., Matsumiya, H., Matthews, J. N., Matuyama, T., Mayta, R., Minamino, M., Mukai, K., Myers, I., Nagataki, S., Nakai, K., Nakamura, R., Nakamura, T., Nakamura, Y., Nonaka, T., Oda, H., Ogio, S., Ohnishi, M., Ohoka, H., Oku, Y., Okuda, T., Omura, Y., Ono, M., Oshima, A., Ozawa, S., Park, I. H., Potts, M., Pshirkov, M. S., Rodriguez, D. C., Rubtsov, G., Ryu, D., Sagawa, H., Sahara, R., Saito, K., Saito, Y., Sakaki, N., Sako, T., Sakurai, N., Sano, K., Seki, T., Sekino, K., Shibata, F., Shibata, T., Shimodaira, H., Shin, B. K., Shin, H. S., Smith, J. D., Sokolsky, P., Sone, N., Stokes, B. T., Stroman, T. A., Takagi, Y., Takahashi, Y., Takeda, M., Takeishi, R., Taketa, A., Takita, M., Tameda, Y., Tanaka, K., Tanaka, M., Tanoue, Y., Thomas, S. B., Thomson, G. B., Tinyakov, P., Tkachev, I., Tokuno, H., Tomida, T., Troitsky, S., Tsunesada, Y., Uchihori, Y., Udo, S., Uehama, T., Urban, F., Wallace, M., Wong, T., Yamamoto, M., Yamaoka, H., Yamazaki, K., Yashiro, K., Yosei, M., Yoshii, H., Zhezher, Y., and Zundel, Z.

Subjects
Physics - Atmospheric and Oceanic Physics, Astrophysics - High Energy Astrophysical Phenomena, High Energy Physics - Experiment
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
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32. Search for Large-scale Anisotropy on Arrival Directions of Ultra-high-energy Cosmic Rays Observed with the Telescope Array Experiment

Author

Telescope Array Collaboration, Abbasi, R. U., Abe, M., Abu-Zayyad, T., Allen, M., Azuma, R., Barcikowski, E., Belz, J. W., Bergman, D. R., Blake, S. A., Cady, R., Cheon, B. G., Chiba, J., Chikawa, M., di Matteo, A., Fujii, T., Fujisue, K., Fujita, K., Fujiwara, R., Fukushima, M., Furlich, G., Hanlon, W., Hayashi, M., Hayashida, N., Hibino, K., Higuchi, R., Honda, K., Ikeda, D., Inadomi, T., Inoue, N., Ishii, T., Ishimori, R., Ito, H., Ivanov, D., Iwakura, H., Jeong, H. M., Jeong, S., Jui, C. C. H., Kadota, K., Kakimoto, F., Kalashev, O., Kasahara, K., Kasami, S., Kawai, H., Kawakami, S., Kawana, S., Kawata, K., Kido, E., Kim, H. B., Kim, J. H., Kim, M. H., Kim, S. W., Kishigami, S., Kuzmin, V., Kuznetsov, M., Kwon, Y. J., Lee, K. H., Lubsandorzhiev, B., Lundquist, J. P., Machida, K., Matsumiya, H., Matsuyama, T., Matthews, J. N., Mayta, R., Minamino, M., Mukai, K., Myers, I., Nagataki, S., Nakai, K., Nakamura, R., Nakamura, T., Nakamura, Y., Nonaka, T., Oda, H., Ogio, S., Ohnishi, M., Ohoka, H., Oku, Y., Okuda, T., Omura, Y., Ono, M., Onogi, R., Oshima, A., Ozawa, S., Park, I. H., Pshirkov, M. S., Remington, J., Rodriguez, D. C., Rubtsov, G., Ryu, D., Sagawa, H., Sahara, R., Saito, Y., Sakaki, N., Sako, T., Sakurai, N., Sano, K., Seki, T., Sekino, K., Shah, P. D., Shibata, F., Shibata, T., Shimodaira, H., Shin, B. K., Shin, H. S., Smith, J. D., Sokolsky, P., Sone, N., Stokes, B. T., Stroman, T. A., Suzawa, T., Takagi, Y., Takahashi, Y., Takamura, M., Takeda, M., Takeishi, R., Taketa, A., Takita, M., Tameda, Y., Tanaka, H., Tanaka, K., Tanaka, M., Tanoue, Y., Thomas, S. B., Thomson, G. B., Tinyakov, P., Tkachev, I., Tokuno, H., Tomida, T., Troitsky, S., Tsunesada, Y., Uchihori, Y., Udo, S., Uehama, T., Urban, F., Wong, T., Yada, K., Yamamoto, M., Yamazaki, K., Yang, J., Yashiro, K., Yosei, M., Zhezher, Y., and Zundel, Z.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
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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33. Measurement of the Proton-Air Cross Section with Telescope Array's Black Rock Mesa and Long Ridge Fluorescence Detectors, and Surface Array in Hybrid Mode

Author

Abbasi, R. U., Abe, M., Abu-Zayyad, T., Allen, M., Azuma, R., Barcikowski, E., Belz, J. W., Bergman, D. R., Blake, S. A., Cady, R., Cheon, B. G., Chiba, J., Chikawa, M., di Matteo, A., Fujii, T., Fujisue, K., Fujita, K., Fujiwara, R., Fukushima, M., Furlich, G., Hanlon, W., Hayashi, M., Hayashida, N., Hibino, K., Higuchi, R., Honda, K., Ikeda, D., Inadomi, T., Inoue, N., Ishii, T., Ishimori, R., Ito, H., Ivanov, D., Iwakura, H., Jeong, H. M., Jeong, S., Jui, C. C. H., Kadota, K., Kakimoto, F., Kalashev, O., Kasahara, K., Kasami, S., Kawai, H., Kawakami, S., Kawana, S., Kawata, K., Kido, E., Kim, H. B., Kim, J. H., Kim, M. H., Kim, S. W., Kishigami, S., Kuzmin, V., Kuznetsov, M., Kwon, Y. J., Lee, K. H., Lubsandorzhiev, B., Lundquist, J. P., Machida, K., Matsumiya, H., Matsuyama, T., Matthews, J. N., Mayta, R., Minamino, M., Mukai, K., Myers, I., Nagataki, S., Nakai, K., Nakamura, R., Nakamura, T., Nakamura, Y., Nonaka, T., Oda, H., Ogio, S., Ohnishi, M., Ohoka, H., Oku, Y., Okuda, T., Omura, Y., Ono, M., Onogi, R., Oshima, A., Ozawa, S., Park, I. H., Pshirkov, M. S., Remington, J., Rodriguez, D. C., Rubtsov, G., Ryu, D., Sagawa, H., Sahara, R., Saito, Y., Sakaki, N., Sako, T., Sakurai, N., Sano, K., Seki, T., Sekino, K., Shah, P. D., Shibata, F., Shibata, T., Shimodaira, H., Shin, B. K., Shin, H. S., Smith, J. D., Sokolsky, P., Sone, N., Stokes, B. T., Stroman, T. A., Suzawa, T., Takagi, Y., Takahashi, Y., Takamura, M., Takeda, M., Takeishi, R., Taketa, A., Takita, M., Tameda, Y., Tanaka, H., Tanaka, K., Tanaka, M., Tanoue, Y., Thomas, S. B., Thomson, G. B., Tinyakov, P., Tkachev, I., Tokuno, H., Tomida, T., Troitsky, S., Tsunesada, Y., Uchihori, Y., Udo, S., Uehama, T., Urban, F., Wong, T., Yada, K., Yamamoto, M., Yamazaki, K., Yang, J., Yashiro, K., Yosei, M., Zhezher, Y., and Zundel, Z.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Ultra high energy cosmic rays provide the highest known energy source in the universe to measure proton cross sections. Though conditions for collecting such data are less controlled than an accelerator environment, current generation cosmic ray observatories have large enough exposures to collect significant statistics for a reliable measurement for energies above what can be attained in the lab. Cosmic ray measurements of cross section use atmospheric calorimetry to measure depth of air shower maximum ($X_{\mathrm{max}}$), which is related to the primary particle's energy and mass. The tail of the $X_{\mathrm{max}}$ distribution is assumed to be dominated by showers generated by protons, allowing measurement of the inelastic proton-air cross section. In this work the proton-air inelastic cross section measurement, $\sigma^{\mathrm{inel}}_{\mathrm{p-air}}$, using data observed by Telescope Array's Black Rock Mesa and Long Ridge fluorescence detectors and surface detector array in hybrid mode is presented. $\sigma^{\mathrm{inel}}_{\mathrm{p-air}}$ is observed to be $520.1 \pm 35.8$[Stat.] $^{+25.0}_{-40}$[Sys.]~mb at $\sqrt{s} = 73$ TeV. The total proton-proton cross section is subsequently inferred from Glauber formalism and is found to be $\sigma^{\mathrm{tot}}_{\mathrm{pp}} = 139.4 ^{+23.4}_{-21.3}$ [Stat.]$ ^{+15.0}_{-24.0}$[Sys.]~mb.

Published
2020
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34. Evidence for a Supergalactic Structure of Magnetic Deflection Multiplets of Ultra-High Energy Cosmic Rays

Author

Telescope Array Collaboration, Abbasi, R. U., Abe, M., Abu-Zayyad, T., Allen, M., Azuma, R., Barcikowski, E., Belz, J. W., Bergman, D. R., Blake, S. A., Cady, R., Cheon, B. G., Chiba, J., Chikawa, M., di Matteo, A., Fujii, T., Fujisue, K., Fujita, K., Fujiwara, R., Fukushima, M., Furlich, G., Hanlon, W., Hayashi, M., Hayashida, N., Hibino, K., Higuchi, R., Honda, K., Ikeda, D., Inadomi, T., Inoue, N., Ishii, T., Ishimori, R., Ito, H., Ivanov, D., Iwakura, H., Jeong, H. M., Jeong, S., Jui, C. C. H., Kadota, K., Kakimoto, F., Kalashev, O., Kasahara, K., Kasami, S., Kawai, H., Kawakami, S., Kawana, S., Kawata, K., Kido, E., Kim, H. B., Kim, J. H., Kim, M. H., Kim, S. W., Kishigami, S., Kuzmin, V., Kuznetsov, M., Kwon, Y. J., Lee, K. H., Lubsandorzhiev, B., Lundquist, J. P., Machida, K., Matsumiya, H., Matsuyama, T., Matthews, J. N., Mayta, R., Minamino, M., Mukai, K., Myers, I., Nagataki, S., Nakai, K., Nakamura, R., Nakamura, T., Nakamura, Y., Nonaka, T., Oda, H., Ogio, S., Ohnishi, M., Ohoka, H., Oku, Y., Okuda, T., Omura, Y., Ono, M., Onogi, R., Oshima, A., Ozawa, S., Park, I. H., Pshirkov, M. S., Remington, J., Rodriguez, D. C., Rubtsov, G., Ryu, D., Sagawa, H., Sahara, R., Saito, Y., Sakaki, N., Sako, T., Sakurai, N., Sano, K., Seki, T., Sekino, K., Shah, P. D., Shibata, F., Shibata, T., Shimodaira, H., Shin, B. K., Shin, H. S., Smith, J. D., Sokolsky, P., Sone, N., Stokes, B. T., Stroman, T. A., Suzawa, T., Takagi, Y., Takahashi, Y., Takamura, M., Takeishi, R., Taketa, A., Takita, M., Tameda, Y., Tanaka, H., Tanaka, K., Tanaka, M., Tanoue, Y., Thomas, S. B., Thomson, G. B., Tinyakov, P., Tkachev, I., Tokuno, H., Tomida, T., Troitsky, S., Tsunesada, Y., Uchihori, Y., Udo, S., Uehama, T., Urban, F., Wong, T., Yada, K., Yamamoto, M., Yamazaki, K., Yang, J., Yashiro, K., Yosei, M., Zhezher, Y., and Zundel, Z.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Evidence for a large-scale supergalactic cosmic ray multiplet (arrival directions correlated with energy) structure is reported for ultra-high energy cosmic ray (UHECR) energies above 10$^{19}$ eV using seven years of data from the Telescope Array (TA) surface detector and updated to 10 years. Previous energy-position correlation studies have made assumptions regarding magnetic field shapes and strength, and UHECR composition. Here the assumption tested is that, since the supergalactic plane is a fit to the average matter density of the local Large Scale Structure (LSS), UHECR sources and intervening extragalactic magnetic fields are correlated with this plane. This supergalactic deflection hypothesis is tested by the entire field-of-view (FOV) behavior of the strength of intermediate-scale energy-angle correlations. These multiplets are measured in spherical cap section bins (wedges) of the FOV to account for coherent and random magnetic fields. The structure found is consistent with supergalactic deflection, the previously published energy spectrum anisotropy results of TA (the hotspot and coldspot), and toy-model simulations of a supergalactic magnetic sheet. The seven year data post-trial significance of this supergalactic structure of multiplets appearing by chance, on an isotropic sky, is found by Monte Carlo simulation to be 4.2$\sigma$. The ten years of data post-trial significance is 4.1$\sigma$. Furthermore, the starburst galaxy M82 is shown to be a possible source of the TA Hotspot, and an estimate of the supergalactic magnetic field using UHECR measurements is presented.

Published
2020

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

Author

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

Published
2023
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36. First Detection of Photons with Energy Beyond 100 TeV from an Astrophysical Source

Author

Amenomori, M., Bao, Y. W., Bi, X. J., Chen, D., Chen, T. L., Chen, W. Y., Chen, Xu, Chen, Y., Cirennima, Cui, S. W., Danzengluobu, Ding, L. K., Fang, J. H., Fang, K., Feng, C. F., Feng, Zhaoyang, Feng, Z. Y., Gao, Qi, Gou, Q. B., Guo, Y. Q., He, H. H., He, Z. T., Hibino, K., Hotta, N., Hu, Haibing, Hu, H. B., Huang, J., Jia, H. Y., Jiang, L., Jin, H. B., Kajino, F., Kasahara, K., Katayose, Y., Kato, C., Kato, S., Kawata, K., Kozai, M., Labaciren, Le, G. M., Li, A. F., Li, H. J., Li, W. J., Lin, Y. H., Liu, B., Liu, C., Liu, J. S., Liu, M. Y., Lou, Y. -Q., Lu, H., Meng, X. R., Mitsui, H., Munakata, K., Nakamura, Y., Nanjo, H., Nishizawa, M., Ohnishi, M., Ohta, I., Ozawa, S., Qian, X. L., Qu, X. B., Saito, T., Sakata, M., Sako, T. K., Sengoku, Y., Shao, J., Shibata, M., Shiomi, A., Sugimoto, H., Takita, M., Tan, Y. H., Tateyama, N., Torii, S., Tsuchiya, H., Udo, S., Wang, H., Wu, H. R., Xue, L., Yagisawa, K., Yamamoto, Y., Yang, Z., Yuan, A. F., Zhai, L. M., Zhang, H. M., Zhang, J. L., Zhang, X., Zhang, X. Y., Zhang, Y., Zhang, Yi, Zhang, Ying, Zhaxisangzhu, and Zhou, X. X.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We report on the highest energy photons from the Crab Nebula observed by the Tibet air shower array with the underground water-Cherenkov-type muon detector array. Based on the criterion of muon number measured in an air shower, we successfully suppress 99.92% of the cosmic-ray background events with energies $E>100$ TeV. As a result, we observed 24 photon-like events with $E>100$ TeV against 5.5 background events, which corresponds to 5.6$\sigma$ statistical significance. This is the first detection of photons with $E>100$ TeV from an astrophysical source., Comment: April 4, 2019; Submitted to the Physical Review Letters

Published
2019
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37. 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

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

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

In this paper, we present the analysis and results of a direct measurement of the cosmic-ray proton spectrum with the CALET instrument onboard the International Space Station, including the detailed assessment of systematic uncertainties. The observation period used in this analysis is from October 13, 2015 to August 31, 2018 (1054 days). We have achieved the very wide energy range necessary to carry out measurements of the spectrum from 50 GeV to 10 TeV covering, for the first time in space, with a single instrument the whole energy interval previously investigated in most cases in separate subranges by magnetic spectrometers (BESS-TeV, PAMELA, and AMS-02) and calorimetric instruments (ATIC, CREAM, and NUCLEON). The observed spectrum is consistent with AMS-02 but extends to nearly an order of magnitude higher energy, showing a very smooth transition of the power-law spectral index from -2.81 +- 0.03 (50--500 GeV) neglecting solar modulation effects (or -2.87 +- 0.06 including solar modulation effects in the lower energy region) to -2.56 +- 0.04 (1--10 TeV), thereby confirming the existence of spectral hardening and providing evidence of a deviation from a single power law by more than 3 sigma., Comment: main text: 8 pages, 5 figures, supplemental material: 12 pages, 7 figures, 1 table, marked as a PRL Editor's Suggestion

Published
2019
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38. Search for Ultra-High-Energy Neutrinos with the Telescope Array Surface Detector

Author

Abbasi, R. U., Abe, M., Abu-Zayyad, T., Allen, M., Barcikowski, E., Belz, J. W., Bergman, D. R., Blake, S. A., Cady, R., Cheon, B. G., Chiba, J., Chikawa, M., di Matteo, A., Fujii, T., Fujisue, K., Fujita, K., Fujiwara, R., Fukushima, M., Furlich, G., Hanlon, W., Hayashi, M., Hayashi, Y., Hayashida, N., Hibino, K., Honda, K., Ikeda, D., Inoue, N., Ishii, T., Ito, H., Ivanov, D., Jeong, H. M., Jeong, S., Jui, C. C. H., Kadota, K., Kakimoto, F., Kalashev, O., Kasahara, K., Kawai, H., Kawakami, S., Kawana, S., Kawata, K., Kido, E., Kim, H. B., Kim, J. H., Kishigami, S., Kuzmin, V., Kuznetsov, M., Kwon, Y. J., Lee, K. H., Lubsandorzhiev, B., Lundquist, J. P., Machida, K., Martens, K., Matsuyama, T., Matthews, J. N., Mayta, R., Minamino, M., Mukai, K., Myers, I., Nagasawa, K., Nagataki, S., Nakai, K., Nakamura, R., Nakamura, T., Nonaka, T., Oda, H., Ogio, S., Ohnishi, M., Ohoka, H., Okuda, T., Omura, Y., Ono, M., Onogi, R., Oshima, A., Ozawa, S., Park, I. H., Pshirkov, M. S., Remington, J., Rodriguez, D. C., Rubtsov, G., Ryu, D., Sagawa, H., Sahara, R., Saito, K., Saito, Y., Sakaki, N., Sako, T., Sakurai, N., Scott, L. M., Seki, T., Sekino, K., Shah, P. D., Shibata, F., Shibata, T., Shimodaira, H., Shin, B. K., Shin, H. S., Smith, J. D., Sokolsky, P., Stokes, B. T., Stratton, S. R., Stroman, T. A., Suzawa, T., Takagi, Y., Takahashi, Y., Takamura, M., Takeda, M., Takeishi, R., Taketa, A., Takita, M., Tameda, Y., Tanaka, H., Tanaka, K., Tanaka, M., Tanoue, Y., Thomas, S. B., Thomson, G. B., Tinyakov, P., Tkachev, I., Tokuno, H., Tomida, T., Troitsky, S., Tsunesada, Y., Uchihori, Y., Udo, S., Urban, F., Wong, T., Yada, K., Yamamoto, M., Yamaoka, H., Yamazaki, K., Yang, J., Yashiro, K., Yoshii, H., Zhezher, Y., and Zundel, Z.

Subjects
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., Comment: 10 pages, 4 figures, accepted to JETP

Published
2019
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39. Search for point sources of ultra-high energy photons with the Telescope Array surface detector

Author

Telescope Array Collaboration, Abbasi, R. U., Abe, M., Abu-Zayyad, T., Allen, M., Azuma, R., Barcikowski, E., Belz, J. W., Bergman, D. R., Blake, S. A., Cady, R., Cheon, B. G., Chiba, J., Chikawa, M., diMatteo, A., Fujii, T., Fujita, K., Fujiwara, R., Fukushima, M., Furlich, G., Hanlon, W., Hayashi, M., Hayashi, Y., Hayashida, N., Hibino, K., Honda, K., Ikeda, D., Inoue, N., Ishii, T., Ishimori, R., Ito, H., Ivanov, D., Jeong, H. M., Jeong, S., Jui, C. C. H., Kadota, K., Kakimoto, F., Kalashev, O., Kasahara, K., Kawai, H., Kawakami, S., Kawana, S., Kawata, K., Kido, E., Kim, H. B., Kim, J. H., Kishigami, S., Kuzmin, V., Kuznetsov, M., Kwon, Y. J., Lee, K. H., Lubsandorzhiev, B., Lundquist, J. P., Machida, K., Martens, K., Matsuyama, T., Matthews, J. N., Mayta, R., Minamino, M., Mukai, K., Myers, I., Nagataki, S., Nakai, K., Nakamura, R., Nakamura, T., Nonaka, T., Oda, H., Ogio, S., Ohnishi, M., Ohoka, H., Okuda, T., Omura, Y., Ono, M., Onogi, R., Oshima, A., Ozawa, S., Park, I. H., Pshirkov, M. S., Remington, J., Rodriguez, D. C., Rubtsov, G., Ryu, D., Sagawa, H., Sahara, R., Saito, K., Saito, Y., Sakaki, N., Sako, T., Sakurai, N., Scott, L. M., Seki, T., Sekino, K., Shah, P. D., Shibata, F., Shibata, T., Shimodaira, H., Shin, B. K., Shin, H. S., Smith, J. D., Sokolsky, P., Stokes, B. T., Stratton, S. R., Stroman, T. A., Suzawa, T., Takagi, Y., Takahashi, Y., Takamura, M., Takeda, M., Takeishi, R., Taketa, A., Takita, M., Tameda, Y., Tanaka, H., Tanaka, K., Tanaka, M., Tanoue, Y., Thomas, S. B., Thomson, G. B., Tinyakov, P., Tkachev, I., Tokuno, H., Tomida, T., Troitsky, S., Tsunesada, Y., Tsutsumi, K., Uchihori, Y., Udo, S., Urban, F., Wong, T., Yada, K., Yamamoto, M., Yamaoka, H., Yamazaki, K., Yang, J., Yashiro, K., Yoshii, H., Zhezher, Y., and Zundel, Z.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
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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40. The CALorimetric Electron Telescope (CALET) on the International Space Station: Results from the First Two Years On Orbit

Author

Asaoka, Y., Adriani, O., Akaike, Y., Asano, K., Bagliesi, M. G., Berti, E., Bigongiari, G., Binns, W. R., Bonechi, S., Bongi, M., Bruno, A., Brogi, P., Buckley, J. H., Cannady, N., Castellini, G., Checchia, C., Cherry, M. L., Collazuol, G., Felice, V. Di., Ebisawa, K., Fuke, H., Guzik, T. G., Hams, T., Hasebe, N., Hibino, K., Ichimura, M., Ioka, K., Ishizaki, W., Israel, M. H., Kasahara, K., Kataoka, J., Kataoka, R., Katayose, Y., Kato, C., Kawanaka, N., Kawakubo, Y., Kohri, K., Krawczynski, H. S., Krizmanic, J. F., Lomtadze, T., Maestro, P., Marrocchesi, P. S., Messineo, A. M., Mitchell, J. W., Miyake, S., Moiseev, A. A., Mori, K., Mori, M., Mori, N., Motz, H. M., Munakata, K., Murakami, H., Nakahira, S., Nishimura, J., Nolfo, G. A. De., Okuno, S., Ormes, J. F., Ozawa, S., Pacini, L., Palma, F., Pal'shin, V., Papini, P., Penacchioni, A. V., Rauch, B. F., Ricciarini, S. B., Sakai, K., Sakamoto, T., Sasaki, M., Shimizu, Y., Shiomi, A., Sparvoli, R., Spillantini, P., Stolzi, F., Sugita, S., Suh, J. E., Sulaj, A., Takahashi, I., Takayanagi, M., Takita, M., Tamura, T., Tateyama, N., Terasawa, T., Tomida, H., Torii, S., Tsunesada, Y., Uchihori, Y., Ueno, S., Vannuccini, E., Wefel, J. P., Yamaoka, K., Yanagita, S., Yoshida, A., and Yoshida, K.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
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., Comment: 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
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41. Constraints on the diffuse photon flux with energies above $10^{18}$ eV using the surface detector of the Telescope Array experiment

Author

Telescope Array Collaboration, Abbasi, R. U., Abe, M., Abu-Zayyad, T., Allen, M., Azuma, R., Barcikowski, E., Belz, J. W., Bergman, D. R., Blake, S. A., Cady, R., Cheon, B. G., Chiba, J., Chikawa, M., di Matteo, A., Fujii, T., Fujita, K., Fukushima, M., Furlich, G., Goto, T., Hanlon, W., Hayashi, M., Hayashi, Y., Hayashida, N., Hibino, K., Honda, K., Ikeda, D., Inoue, N., Ishii, T., Ishimori, R., Ito, H., Ivanov, D., Jeong, H. M., Jeong, S., Jui, C. C. H., Kadota, K., Kakimoto, F., Kalashev, O., Kasahara, K., Kawai, H., Kawakami, S., Kawana, S., Kawata, K., Kido, E., Kim, H. B., Kim, J. H., Kishigami, S., Kitamura, S., Kitamura, Y., Kuzmin, V., Kuznetsov, M., Kwon, Y. J., Lee, K. H., Lubsandorzhiev, B., Lundquist, J. P., Machida, K., Martens, K., Matsuyama, T., Matthews, J. N., Mayta, R., Minamino, M., Mukai, K., Myers, I., Nagasawa, K., Nagataki, S., Nakamura, R., Nakamura, T., Nonaka, T., Oda, H., Ogio, S., Ogura, J., Ohnishi, M., Ohoka, H., Okuda, T., Omura, Y., Ono, M., Onogi, R., Oshima, A., Ozawa, S., Park, I. H., Piskunov, M. S., Pshirkov, M. S., Remington, J., Rodriguez, D. C., Rubtsov, G., Ryu, D., Sagawa, H., Sahara, R., Saito, K., Saito, Y., Sakaki, N., Sakurai, N., Scott, L. M., Seki, T., Sekino, K., Shah, P. D., Shibata, F., Shibata, T., Shimodaira, H., Shin, B. K., Shin, H. S., Smith, J. D., Sokolsky, P., Stokes, B. T., Stratton, S. R., Stroman, T. A., Suzawa, T., Takagi, Y., Takahashi, Y., Takamura, M., Takeda, M., Takeishi, R., Taketa, A., Takita, M., Tameda, Y., Tanaka, H., Tanaka, K., Tanaka, M., Thomas, S. B., Thomson, G. B., Tinyakov, P., Tkachev, I., Tokuno, H., Tomida, T., Troitsky, S., Tsunesada, Y., Tsutsumi, K., Uchihori, Y., Udo, S., Urban, F., Wong, T., Yamamoto, M., Yamane, R., Yamaoka, H., Yamazaki, K., Yang, J., Yashiro, K., Yoneda, Y., Yoshida, S., Yoshii, H., Zhezher, Y., and Zundel, Z.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, High Energy Physics - Experiment, High Energy Physics - Phenomenology
Abstract

We present the results of the search for ultra-high-energy photons with nine years of data from the Telescope Array surface detector. A multivariate classifier is built upon 16 reconstructed parameters of the extensive air shower. These parameters are related to the curvature and the width of the shower front, the steepness of the lateral distribution function, and the timing parameters of the waveforms sensitive to the shower muon content. A total number of two photon candidates found in the search is fully compatible with the expected background. The $95\%\,$CL limits on the diffuse flux of the photons with energies greater than $10^{18.0}$, $10^{18.5}$, $10^{19.0}$, $10^{19.5}$ and $10^{20.0}$ eV are set at the level of $0.067$, $0.012$, $0.0036$, $0.0013$, $0.0013~\mbox{km}^{-2}\mbox{yr}^{-1}\mbox{sr}^{-1}$ correspondingly., Comment: 7 pages, 2 figures

Published
2018
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42. Testing a reported correlation between arrival directions of ultrahigh-energy cosmic rays and a flux pattern from nearby starburst galaxies using Telescope Array data

Author

Telescope Array Collaboration, Abbasi, R. U., Abe, M., Abu-Zayyad, T., Allen, M., Azuma, R., Barcikowski, E., Belz, J. W., Bergman, D. R., Blake, S. A., Cady, R., Cheon, B. G., Chiba, J., Chikawa, M., di Matteo, A., Fujii, T., Fujita, K., Fukushima, M., Furlich, G., Goto, T., Hanlon, W., Hayashi, M., Hayashi, Y., Hayashida, N., Hibino, K., Honda, K., Ikeda, D., Inoue, N., Ishii, T., Ishimori, R., Ito, H., Ivanov, D., Jeong, H. M., Jeong, S., Jui, C. C. H., Kadota, K., Kakimoto, F., Kalashev, O., Kasahara, K., Kawai, H., Kawakami, S., Kawana, S., Kawata, K., Kido, E., Kim, H. B., Kim, J. H., Kishigami, S., Kitamura, S., Kitamura, Y., Kuzmin, V., Kuznetsov, M., Kwon, Y. J., Lee, K. H., Lubsandorzhiev, B., Lundquist, J. P., Machida, K., Martens, K., Matsuyama, T., Matthews, J. N., Mayta, R., Minamino, M., Mukai, K., Myers, I., Nagasawa, K., Nagataki, S., Nakamura, R., Nakamura, T., Nonaka, T., Oda, H., Ogio, S., Ogura, J., Ohnishi, M., Ohoka, H., Okuda, T., Omura, Y., Ono, M., Onogi, R., Oshima, A., Ozawa, S., Park, I. H., Pshirkov, M. S., Remington, J., Rodriguez, D. C., Rubtsov, G., Ryu, D., Sagawa, H., Sahara, R., Saito, K., Saito, Y., Sakaki, N., Sakurai, N., Scott, L. M., Seki, T., Sekino, K., Shah, P. D., Shibata, F., Shibata, T., Shimodaira, H., Shin, B. K., Shin, H. S., Smith, J. D., Sokolsky, P., Stokes, B. T., Stratton, S. R., Stroman, T. A., Suzawa, T., Takagi, Y., Takahashi, Y., Takamura, M., Takeda, M., Takeishi, R., Taketa, A., Takita, M., Tameda, Y., Tanaka, H., Tanaka, K., Tanaka, M., Thomas, S. B., Thomson, G. B., Tinyakov, P., Tkachev, I., Tokuno, H., Tomida, T., Troitsky, S., Tsunesada, Y., Tsutsumi, K., Uchihori, Y., Udo, S., Urban, F., Wong, T., Yamamoto, M., Yamane, R., Yamaoka, H., Yamazaki, K., Yang, J., Yashiro, K., Yoneda, Y., Yoshida, S., Yoshii, H., Zhezher, Y., and Zundel, Z.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

The Pierre Auger Collaboration (Auger) recently reported a correlation between the arrival directions of cosmic rays with energies above 39 EeV and the flux pattern of 23 nearby starburst galaxies (SBGs). In this Letter, we tested the same hypothesis using cosmic rays detected by the Telescope Array experiment (TA) in the 9-year period from May 2008 to May 2017. Unlike the Auger analysis, we did not optimize the parameter values but kept them fixed to the best-fit values found by Auger, namely 9.7% for the anisotropic fraction of cosmic rays assumed to originate from the SBGs in the list and 12.9{\deg} for the angular scale of the correlations. The energy threshold we adopted is 43 EeV, corresponding to 39 EeV in Auger when taking into account the energy-scale difference between two experiments. We find that the TA data is compatible with isotropy to within 1.1{\sigma} and with the Auger result to within 1.4{\sigma}, meaning that it is not capable to discriminate between these two hypotheses., Comment: More accurate title, fixed an inconsistency in the declination range used, with a few figures slightly changing as a result, other minor revisions

Published
2018
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43. Mass composition of ultra-high-energy cosmic rays with the Telescope Array Surface Detector Data

Author

Telescope Array Collaboration, Abbasi, R. U., Abe, M., Abu-Zayyad, T., Allen, M., Azuma, R., Barcikowski, E., Belz, J. W., Bergman, D. R., Blake, S. A., Cady, R., Cheon, B. G., Chiba, J., Chikawa, M., di Matteo, A., Fujii, T., Fujita, K., Fukushima, M., Furlich, G., Goto, T., Hanlon, W., Hayashi, M., Hayashi, Y., Hayashida, N., Hibino, K., Honda, K., Ikeda, D., Inoue, N., Ishii, T., Ishimori, R., Ito, H., Ivanov, D., Jeong, H. M., Jeong, S., Jui, C. C. H., Kadota, K., Kakimoto, F., Kalashev, O., Kasahara, K., Kawai, H., Kawakami, S., Kawana, S., Kawata, K., Kido, E., Kim, H. B., Kim, J. H., Kishigami, S., Kitamura, S., Kitamura, Y., Kuzmin, V., Kuznetsov, M., Kwon, Y. J., Lee, K. H., Lubsandorzhiev, B., Lundquist, J. P., Machida, K., Martens, K., Matsuyama, T., Matthews, J. N., Mayta, R., Minamino, M., Mukai, K., Myers, I., Nagasawa, K., Nagataki, S., Nakamura, R., Nakamura, T., Nonaka, T., Oda, H., Ogio, S., Ogura, J., Ohnishi, M., Ohoka, H., Okuda, T., Omura, Y., Ono, M., Onogi, R., Oshima, A., Ozawa, S., Park, I. H., Piskunov, M. S., Pshirkov, M. S., Remington, J., Rodriguez, D. C., Rubtsov, G., Ryu, D., Sagawa, H., Sahara, R., Saito, K., Saito, Y., Sakaki, N., Sakurai, N., Scott, L. M., Seki, T., Sekino, K., Shah, P. D., Shibata, F., Shibata, T., Shimodaira, H., Shin, B. K., Shin, H. S., Smith, J. D., Sokolsky, P., Stokes, B. T., Stratton, S. R., Stroman, T. A., Suzawa, T., Takagi, Y., Takahashi, Y., Takamura, M., Takeda, M., Takeishi, R., Taketa, A., Takita, M., Tameda, Y., Tanaka, H., Tanaka, K., Tanaka, M., Thomas, S. B., Thomson, G. B., Tinyakov, P., Tkachev, I., Tokuno, H., Tomida, T., Troitsky, S., Tsunesada, Y., Tsutsumi, K., Uchihori, Y., Udo, S., Urban, F., Wong, T., Yamamoto, M., Yamane, R., Yamaoka, H., Yamazaki, K., Yang, J., Yashiro, K., Yoneda, Y., Yoshida, S., Yoshii, H., Zhezher, Y., and Zundel, Z.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

The results on ultra-high-energy cosmic rays (UHECR) mass composition obtained with the Telescope Array surface detector are presented. The analysis employs the boosted decision tree (BDT) multivariate analysis built upon 14 observables related to both the properties of the shower front and the lateral distribution function. The multivariate classifier is trained with Monte-Carlo sets of events induced by the primary protons and iron. An average atomic mass of UHECR is presented for energies $10^{18.0}-10^{20.0}\ \mbox{eV}$. The average atomic mass of primary particles shows no significant energy dependence and corresponds to $\langle \ln A \rangle = 2.0 \pm 0.1 (stat.) \pm 0.44 (syst.)$. The result is compared to the mass composition obtained by the Telescope Array with $\mbox{X}_{\mbox{max}}$ technique along with the results of other experiments. Possible systematic errors of the method are discussed., Comment: 11 pages, 9 figures

Published
2018
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44. Search for GeV Gamma-ray Counterparts of Gravitational Wave Events by CALET

Author

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

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We present results on searches for gamma-ray counterparts of the LIGO/Virgo gravitational-wave events using CALorimetric Electron Telescope ({\sl CALET}) observations. The main instrument of {\sl CALET}, CALorimeter (CAL), observes gamma-rays from $\sim1$ GeV up to 10 TeV with a field of view of nearly 2 sr. In addition, the {\sl CALET} gamma-ray burst monitor (CGBM) views $\sim$3 sr and $\sim2\pi$ sr of the sky in the 7 keV -- 1 MeV and the 40 keV -- 20 MeV bands, respectively, by using two different crystal scintillators. The {\sl CALET} observations on the International Space Station started in October 2015, and here we report analyses of events associated with the following gravitational wave events: GW151226, GW170104, GW170608, GW170814 and GW170817. Although only upper limits on gamma-ray emission are obtained, they correspond to a luminosity of $10^{49}\sim10^{53}$ erg s$^{-1}$ in the GeV energy band depending on the distance and the assumed time duration of each event, which is approximately the order of luminosity of typical short gamma-ray bursts. This implies there will be a favorable opportunity to detect high-energy gamma-ray emission in further observations if additional gravitational wave events with favorable geometry will occur within our field-of-view. We also show the sensitivity of {\sl CALET} for gamma-ray transient events which is the order of $10^{-7}$~erg\,cm$^{-2}$\,s$^{-1}$ for an observation of 100~s duration., Comment: 12 pages, 8 figures, 1 table. Accepted for publication in Astrophysical Journal

Published
2018
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45. 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

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

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Extended results on the cosmic-ray electron + positron spectrum from 11 GeV to 4.8 TeV are presented based on observations with the Calorimetric Electron Telescope (CALET) on the International Space Station utilizing the data up to November 2017. The analysis uses the full detector acceptance at high energies, approximately doubling the statistics compared to the previous result. CALET is an all-calorimetric instrument with a total thickness of 30 $X_0$ at normal incidence and fine imaging capability, designed to achieve large proton rejection and excellent energy resolution well into the TeV energy region. The observed energy spectrum in the region below 1 TeV shows good agreement with Alpha Magnetic Spectrometer (AMS-02) data. In the energy region below $\sim$300 GeV, CALET's spectral index is found to be consistent with the AMS-02, Fermi Large Area Telescope (Fermi-LAT) and Dark Matter Particle Explorer (DAMPE), while from 300 to 600 GeV the spectrum is significantly softer than the spectra from the latter two experiments. The absolute flux of CALET is consistent with other experiments at around a few tens of GeV. However, it is lower than those of DAMPE and Fermi-LAT with the difference increasing up to several hundred GeV. The observed energy spectrum above $\sim$1 TeV suggests a flux suppression consistent within the errors with the results of DAMPE, while CALET does not observe any significant evidence for a narrow spectral feature in the energy region around 1.4 TeV. Our measured all-electron flux, including statistical errors and a detailed breakdown of the systematic errors, is tabulated in the Supplemental Material in order to allow more refined spectral analyses based on our data., Comment: main text: 7 pages, 4 figures, supplemental material: 8pages, 6 figures, 2 tables

Published
2018
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46. Influence of Earth-Directed Coronal Mass Ejections on the Sun's Shadow Observed by the Tibet-III Air Shower Array

Author

Amenomori, M., Bi, X. J., Chen, D., Chen, T. L., Chen, W. Y., Cui, S. W., Danzengluobu, Ding, L. K., Feng, C. F., Feng, Zhaoyang, Feng, Z. Y., Gou, Q. B., Guo, Y. Q., He, H. H., He, Z. T., Hibino, K., Hotta, N., Hu, Haibing, Hu, H. B., Huang, J., Jia, H. Y., Jiang, L., Kajino, F., Kasahara, K., Katayose, Y., Kato, C., Kawata, K., Kozai, M., Labaciren, Le, G. M., Li, A. F., Li, H. J., Li, W. J., Liu, C., Liu, J. S., Liu, M. Y., Lu, H., Meng, X. R., Miyazaki, T., Munakata, K., Nakajima, T., Nakamura, Y., Nanjo, H., Nishizawa, M., Niwa, T., Ohnishi, M., Ohta, I., Ozawa, S., Qian, X. L., Qu, X. B., Saito, T., Saito, T. Y., Sakata, M., Sako, T. K., Shao, J., Shibata, M., Shiomi, A., Shirai, T., Sugimoto, H., Takita, M., Tan, Y. H., Tateyama, N., Torii, S., Tsuchiya, H., Udo, S., Wang, H., Wu, H. R., Xue, L., Yamamoto, Y., Yamauchi, K., Yang, Z., Yuan, S. A. F., Zhai, L. M., Zhang, H. M., Zhang, J. L., Zhang, X. Y., Zhang, Y., Zhang, Yi, Zhang, Ying, Zhaxisangzhu, and Zho, X. X.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We examine the possible influence of Earth-directed coronal mass ejections (ECMEs) on the Sun's shadow in the 3~TeV cosmic-ray intensity observed by the Tibet-III air shower (AS) array. We confirm a clear solar-cycle variation of the intensity deficit in the Sun's shadow during ten years between 2000 and 2009. This solar-cycle variation is overall reproduced by our Monte Carlo (MC) simulations of the Sun's shadow based on the potential field model of the solar magnetic field averaged over each solar rotation period. We find, however, that the magnitude of the observed intensity deficit in the Sun's shadow is significantly less than that predicted by MC simulations, particularly during the period around solar maximum when a significant number of ECMEs is recorded. The $\chi^2$ tests of the agreement between the observations and the MC simulations show that the difference is larger during the periods when the ECMEs occur, and the difference is reduced if the periods of ECMEs are excluded from the analysis. This suggests the first experimental evidence of the ECMEs affecting the Sun's shadow observed in the 3~TeV cosmic-ray intensity., Comment: 11 pages, 3 figures, accepted for publication in the ApJ

Published
2018
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47. Study of muons from ultra-high energy cosmic ray air showers measured with the Telescope Array experiment

Author

Telescope Array Collaboration, Abbasi, R. U., Abe, M., Abu-Zayyad, T., Allen, M., Azuma, R., Barcikowski, E., Belz, J. W., Bergman, D. R., Blake, S. A., Cady, R., Cheon, B. G., Chiba, J., Chikawa, M., Di Matteo, A., Fujii, T., Fujita, K., Fukushima, M., Furlich, G., Goto, T., Hanlon, W., Hayashi, M., Hayashi, Y., Hayashida, N., Hibino, K., Honda, K., Ikeda, D., Inoue, N., Ishii, T., Ishimori, R., Ito, H., Ivanov, D., Jeong, H. M., Jeong, S. M., Jui, C. C. H., Kadota, K., Kakimoto, F., Kalashev, O., Kasahara, K., Kawai, H., Kawakami, S., Kawana, S., Kawata, K., Kido, E., Kim, H. B., Kim, J. H., Kishigami, S., Kitamura, S., Kitamura, Y., Kuzmin, V., Kuznetsov, M., Kwon, Y. J., Lee, K. H., Lubsandorzhiev, B., Lundquist, J. P., Machida, K., Martens, K., Matsuyama, T., Matthews, J. N., Mayta, R., Minamino, M., Mukai, K., Myers, I., Nagasawa, K., Nagataki, S., Nakamura, R., Nakamura, T., Nonaka, T., Oda, H., Ogio, S., Ogura, J., Ohnishi, M., Ohoka, H., Okuda, T., Omura, Y., Ono, M., Onogi, R., Oshima, A., Ozawa, S., Park, I. H., Pshirkov, M. S., Remington, J., Rodriguez, D. C., Rubtsov, G., Ryu, D., Sagawa, H., Sahara, R., Saito, K., Saito, Y., Sakaki, N., Sakurai, N., Scott, L. M., Seki, T., Sekino, K., Shah, P. D., Shibata, F., Shibata, T., Shimodaira, H., Shin, B. K., Shin, H. S., Smith, J. D., Sokolsky, P., Stokes, B. T., Stratton, S. R., Stroman, T. A., Suzawa, T., Takagi, Y., Takahashi, Y., Takamura, M., Takeda, M., Takeishi, R., Taketa, A., Takita, M., Tameda, Y., Tanaka, H., Tanaka, K., Tanaka, M., Thomas, S. B., Thomson, G. B., Tinyakov, P., Tkachev, I., Tokuno, H., Tomida, T., Troitsky, S., Tsunesada, Y., Tsutsumi, K., Uchihori, Y., Udo, S., Urban, F., Wong, T., Yamamoto, M., Yamane, R., Yamaoka, H., Yamazaki, K., Yang, J., Yashiro, K., Yoneda, Y., Yoshida, S., Yoshii, H., Zhezher, Y., and Zundel, Z.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

One of the uncertainties in interpretation of ultra-high energy cosmic ray (UHECR) data comes from the hadronic interaction models used for air shower Monte Carlo (MC) simulations. The number of muons observed at the ground from UHECR-induced air showers is expected to depend upon the hadronic interaction model. One may therefore test the hadronic interaction models by comparing the measured number of muons with the MC prediction. In this paper, we present the results of studies of muon densities in UHE extensive air showers obtained by analyzing the signal of surface detector stations which should have high $\it{muon \, purity}$. The muon purity of a station will depend on both the inclination of the shower and the relative position of the station. In 7 years' data from the Telescope Array experiment, we find that the number of particles observed for signals with an expected muon purity of $\sim$65% at a lateral distance of 2000 m from the shower core is $1.72 \pm 0.10{\rm (stat.)} \pm 0.37 {\rm (syst.)}$ times larger than the MC prediction value using the QGSJET II-03 model for proton-induced showers. A similar effect is also seen in comparisons with other hadronic models such as QGSJET II-04, which shows a $1.67 \pm 0.10 \pm 0.36$ excess. We also studied the dependence of these excesses on lateral distances and found a slower decrease of the lateral distribution of muons in the data as compared to the MC, causing larger discrepancy at larger lateral distances.

Published
2018
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48. On-orbit Operations and Offline Data Processing of CALET onboard the ISS

Author

Asaoka, Y., Ozawa, S., Torii, S., Adriani, O., Akaike, Y., Asano, K., Bagliesi, M. G., Bigongiari, G., Binns, W. R., Bonechi, S., Bongi, M., Brogi, P., Buckley, J. H., Cannady, N., Castellini, G., Checchia, C., Cherry, M. L., Collazuol, G., Di Felice, V., Ebisawa, K., Fuke, H., Guzik, T. G., Hams, T., Hareyama, M., Hasebe, N., Hibino, K., Ichimura, M., Ioka, K., Ishizaki, W., Israel, M. H., Javaid, A., Kasahara, K., Kataoka, J., Kataoka, R., Katayose, Y., Kato, C., Kawanaka, N., Kawakubo, Y., Kohri, K., Krawczynski, H. S., Krizmanic, J. F., Kuramata, S., Lomtadze, T., Maestro, P., Marrocchesi, P. S., Messineo, A. M., Mitchell, J. W., Miyake, S., Mizutani, K., Moiseev, A. A., Mori, K., Mori, M., Mori, N., Motz, H. M., Munakata, K., Murakami, H., Nakahira, S., Nishimura, J., de Nolfo, G. A., Okuno, S., Ormes, J. F., Pacini, L., Palma, F., Papini, P., Penacchioni, A. V., Rauch, B. F., Ricciarini, S. B., Sakai, K., Sakamoto, T., Sasaki, M., Shimizu, Y., Shiomi, A., Sparvoli, R., Spillantini, P., Stolzi, F., Takahashi, I., Takayanagi, M., Takita, M., Tamura, T., Tateyama, N., Terasawa, T., Tomida, H., Tsunesada, Y., Uchihori, Y., Ueno, S., Vannuccini, E., Wefel, J. P., Yamaoka, K., Yanagita, S., Yoshida, A., Yoshida, K., and Yuda, T.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Physics - Instrumentation and Detectors
Abstract

The CALorimetric Electron Telescope (CALET), launched for installation on the International Space Station (ISS) in August, 2015, has been accumulating scientific data since October, 2015. CALET is intended to perform long-duration observations of high-energy cosmic rays onboard the ISS. CALET directly measures the cosmic-ray electron spectrum in the energy range of 1 GeV to 20 TeV with a 2% energy resolution above 30 GeV. In addition, the instrument can measure the spectrum of gamma rays well into the TeV range, and the spectra of protons and nuclei up to a PeV. In order to operate the CALET onboard ISS, JAXA Ground Support Equipment (JAXA-GSE) and the Waseda CALET Operations Center (WCOC) have been established. Scientific operations using CALET are planned at WCOC, taking into account orbital variations of geomagnetic rigidity cutoff. Scheduled command sequences are used to control the CALET observation modes on orbit. Calibration data acquisition by, for example, recording pedestal and penetrating particle events, a low-energy electron trigger mode operating at high geomagnetic latitude, a low-energy gamma-ray trigger mode operating at low geomagnetic latitude, and an ultra heavy trigger mode, are scheduled around the ISS orbit while maintaining maximum exposure to high-energy electrons and other high-energy shower events by always having the high-energy trigger mode active. The WCOC also prepares and distributes CALET flight data to collaborators in Italy and the United States. As of August 31, 2017, the total observation time is 689 days with a live time fraction of the total time of approximately 84%. Nearly 450 million events are collected with a high-energy (E>10 GeV) trigger. By combining all operation modes with the excellent-quality on-orbit data collected thus far, it is expected that a five-year observation period will provide a wealth of new and interesting results., Comment: 11 pages, 7 figures, published online 27 February 2018

Published
2018
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49. The Cosmic-Ray Energy Spectrum between 2 PeV and 2 EeV Observed with the TALE detector in monocular mode

Author

Abbasi, R. U., Abe, M., Abu-Zayyad, T., Allen, M., Azuma, R., Barcikowski, E., Belz, J. W., Bergman, D. R., Blake, S. A., Cady, R., Cheon, B. G., Chiba, J., Chikawa, M., Di Matteo, A., Fujii, T., Fujita, K., Fukushima, M., Furlich, G., Goto, T., Hanlon, W., Hayashi, M., Hayashi, Y., Hayashida, N., Hibino, K., Honda, K., Ikeda, D., Inoue, N., Ishii, T., Ishimori, R., Ito, H., Ivanov, D., Jeong, H. M., Jeong, S. M., Jui, C. C. H., Kadota, K., Kakimoto, F., Kalashev, O., Kasahara, K., Kawai, H., Kawakami, S., Kawana, S., Kawata, K., Kido, E., Kim, H. B., Kim, J. H., Kishigami, S., Kitamura, S., Kitamura, Y., Kuzmin, V., Kuznetsov, M., Kwon, Y. J., Lee, K. H., Lubsandorzhiev, B., Lundquist, J. P., Machida, K., Martens, K., Matsuyama, T., Matthews, J. N., Mayta, R., Minamino, M., Mukai, K., Myers, I., Nagasawa, K., Nagataki, S., Nakamura, R., Nakamura, T., Nonaka, T., Nozato, A., Oda, H., Ogio, S., Ogura, J., Ohnishi, M., Ohoka, H., Okuda, T., Omura, Y., Ono, M., Onogi, R., Oshima, A., Ozawa, S., Park, I. H., Pshirkov, M. S., Rodriguez, D. C., Rubtsov, G., Ryu, D., Sagawa, H., Sahara, R., Saito, K., Saito, Y., Sakaki, N., Sakurai, N., Scott, L. M., Seki, T., Sekino, K., Shah, P. D., Shibata, F., Shibata, T., Shimodaira, H., Shin, B. K., Shin, H. S., Smith, J. D., Sokolsky, P., Stokes, B. T., Stratton, S. R., Stroman, T. A., Suzawa, T., Takagi, Y., Takahashi, Y., Takamura, M., Takeda, M., Takeishi, R., Taketa, A., Takita, M., Tameda, Y., Tanaka, H., Tanaka, K., Tanaka, M., Thomas, S. B., Thomson, G. B., Tinyakov, P., Tkachev, I., Tokuno, H., Tomida, T., Troitsky, S., Tsunesada, Y., Tsutsumi, K., Uchihori, Y., Udo, S., Urban, F., Wong, T., Yamamoto, M., Yamane, R., Yamaoka, H., Yamazaki, K., Yang, J., Yashiro, K., Yoneda, Y., Yoshida, S., Yoshii, H., Zhezher, Y., and Zundel, Z.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

We report on a measurement of the cosmic ray energy spectrum by the Telescope Array Low-Energy Extension (TALE) air fluorescence detector. The TALE air fluorescence detector is also sensitive to the Cherenkov light produced by shower particles. Low energy cosmic rays, in the PeV energy range, are detectable by TALE as "Cherenkov Events". Using these events, we measure the energy spectrum from a low energy of $\sim 2$ PeV to an energy greater than 100 PeV. Above 100 PeV TALE can detect cosmic rays using air fluorescence. This allows for the extension of the measurement to energies greater than a few EeV. In this paper, we will describe the detector, explain the technique, and present results from a measurement of the spectrum using $\sim 1000$ hours of observation. The observed spectrum shows a clear steepening near $10^{17.1}$ eV, along with an ankle-like structure at $10^{16.2}$ eV. These features present important constraints on galactic cosmic rays origin and propagation models. The feature at $10^{17.1}$ eV may also mark the end of the galactic cosmic rays flux and the start of the transition to extra-galactic sources., Comment: 26 pages, 24 figures, submitted to ApJ

Published
2018
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50. Evidence of Intermediate-Scale Energy Spectrum Anisotropy of Cosmic Rays E$\geq$10$^{19.2}$ eV with the Telescope Array Surface Detector

Author

Abbasi, R. U., Abe, M., Abu-Zayyad, T., Allen, M., Azuma, R., Barcikowski, E., Belz, J. W., Bergman, D. R., Blake, S. A., Cady, R., Cheon, B. G., Chiba, J., Chikawa, M., Di Matteo, A., Fujii, T., Fujita, K., Fukushima, M., Furlich, G., Goto, T., Hanlon, W., Hayashi, M., Hayashi, Y., Hayashida, N., Hibino, K., Honda, K., Ikeda, D., Inoue, N., Ishii, T., Ishimori, R., Ito, H., Ivanov, D., Jeong, H. M., Jeong, S. M., Jui, C. C. H., Kadota, K., Kakimoto, F., Kalashev, O., Kasahara, K., Kawai, H., Kawakami, S., Kawana, S., Kawata, K., Kido, E., Kim, H. B., Kim, J. H., Kishigami, S., Kitamura, S., Kitamura, Y., Kuzmin, V., Kuznetsov, M., Kwon, Y. J., Lee, K. H., Lubsandorzhiev, B., Lundquist, J. P., Machida, K., Martens, K., Matsuyama, T., Matthews, J. N., Mayta, R., Minamino, M., Mukai, K., Myers, I., Nagasawa, K., Nagataki, S., Nakamura, R., Nakamura, T., Nonaka, T., Nozato, A., Oda, H., Ogio, S., Ogura, J., Ohnishi, M., Ohoka, H., Okuda, T., Omura, Y., Ono, M., Onogi, R., Oshima, A., Ozawa, S., Park, I. H., Pshirkov, M. S., Rodriguez, D. C., Rubtsov, G., Ryu, D., Sagawa, H., Sahara, R., Saito, K., Saito, Y., Sakaki, N., Sakurai, N., Scott, L. M., Seki, T., Sekino, K., Shah, P. D., Shibata, F., Shibata, T., Shimodaira, H., Shin, B. K., Shin, H. S., Smith, J. D., Sokolsky, P., Stokes, B. T., Stratton, S. R., Stroman, T. A., Suzawa, T., Takagi, Y., Takahashi, Y., Takamura, M., Takeishi, R., Taketa, A., Takita, M., Tameda, Y., Tanaka, H., Tanaka, K., Tanaka, M., Thomas, S. B., Thomson, G. B., Tinyakov, P., Tkachev, I., Tokuno, H., Tomida, T., Troitsky, S., Tsunesada, Y., Tsutsumi, K., Uchihori, Y., Udo, S., Urban, F., Wong, T., Yamamoto, M., Yamane, R., Yamaoka, H., Yamazaki, K., Yang, J., Yashiro, K., Yoneda, Y., Yoshida, S., Yoshii, H., Zhezher, Y., and Zundel, Z.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

An intermediate-scale energy spectrum anisotropy has been found in the arrival directions of ultra-high energy cosmic rays of energies above $10^{19.2}$ eV in the northern hemisphere, using 7 years of data from the Telescope Array surface detector. A relative energy distribution test is done comparing events inside oversampled spherical caps of equal exposure, to those outside, using the Poisson likelihood ratio. The center of maximum significance is at $9^h$$16^m$, $45^{\circ}$. and has a deficit of events with energies $10^{19.2}$$\leq$$E$$<$$10^{19.75}$ eV and an excess for $E$$\geq$$10^{19.75}$ eV. The post-trial probability of this energy anisotropy, appearing by chance anywhere on an isotropic sky, is found by Monte Carlo simulation to be $9$$\times$$10^{-5}$ ($3.74$$\sigma_{global}$).

Published
2018
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