Author: "Wu, C.-Y." / Topic: astrophysics - high energy astrophysical phenomena - Searchworks@Jio Institute Digital Library Search Results

Your search keyword '"Wu, C.-Y."' showing total 46 results

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46 results on '"Wu, C.-Y."'

1. Detection of two TeV gamma-ray outbursts from NGC 1275 by LHAASO

Author: Cao, Zhen, Aharonian, F., Axikegu, Bai, Y. X., Bao, Y. W., Bastieri, D., Bi, X. J., Bi, Y. J., Cai, J. T., Cao, Q., Cao, W. Y., Cao, Zhe, Chang, J., Chang, J. F., Chen, A. M., Chen, E. S., Chen, Liang, Chen, Lin, Chen, Long, Chen, M. J., Chen, M. L., Chen, Q. H., Chen, S. H., Chen, S. Z., Chen, T. L., Chen, Y., Cheng, N., Cheng, Y. D., Cui, M. Y., Cui, S. W., Cui, X. H., Cui, Y. D., Dai, B. Z., Dai, H. L., Dai, Z. G., Danzengluobu, della Volpe, D., Dong, X. Q., Duan, K. K., Fan, J. H., Fan, Y. Z., Fang, J., Fang, K., Feng, C. F., Feng, L., Feng, S. H., Feng, X. T., Feng, Y. L., Gabici, S., Gao, B., Gao, C. D., Gao, L. Q., Gao, Q., Gao, W., Gao, W. K., Ge, M. M., Geng, L. S., Giacinti, G., Gong, G. H., Gou, Q. B., Gu, M. H., Guo, F. L., Guo, X. L., Guo, Y. Q., Guo, Y. Y., Han, Y. A., He, H. H., He, H. N., He, J. Y., He, X. B., He, Y., Heller, M., Hor, Y. K., Hou, B. W., Hou, C., Hou, X., Hu, H. B., Hu, Q., Hu, S. C., Huang, D. H., Huang, T. Q., Huang, W. J., Huang, X. T., Huang, X. Y., Huang, Y., Huang, Z. C., Ji, X. L., Jia, H. Y., Jia, K., Jiang, K., Jiang, X. W., Jiang, Z. J., Jin, M., Kang, M. M., Ke, T., Kuleshov, D., Kurinov, K., Li, B. B., Li, Cheng, Li, Cong, Li, D., Li, F., Li, H. B., Li, H. C., Li, H. Y., Li, J., Li, Jian, Li, Jie, Li, K., Li, W. L., Li, X. R., Li, Xin, Li, Y. Z., Li, Zhe, Li, Zhuo, Liang, E. W., Liang, Y. F., Lin, S. J., Liu, B., Liu, C., Liu, D., Liu, H., Liu, H. D., Liu, J., Liu, J. L., Liu, J. Y., Liu, M. Y., Liu, R. Y., Liu, S. M., Liu, W., Liu, Y., Liu, Y. N., Lu, R., Luo, Q., Lv, H. K., Ma, B. Q., Ma, L. L., Ma, X. H., Mao, J. R., Min, Z., Mitthumsiri, W., Mu, H. J., Nan, Y. C., Neronov, A., Ou, Z. W., Pang, B. Y., Pattarakijwanich, P., Pei, Z. Y., Qi, M. Y., Qi, Y. Q., Qiao, B. Q., Qin, J. J., Ruffolo, D., Sáiz, A., Semikoz, D., Shao, C. Y., Shao, L., Shchegolev, O., Sheng, X. D., Shu, F. W., Song, H. C., Stenkin, Yu. V., Stepanov, V., Su, Y., Sun, Q. N., Sun, X. N., Sun, Z. B., Tam, P. H. T., Tang, Q. W., Tang, Z. B., Tian, W. W., Wang, C., Wang, C. B., Wang, G. W., Wang, H. G., Wang, H. H., Wang, J. C., Wang, K., Wang, L. P., Wang, L. Y., Wang, P. H., Wang, R., Wang, W., Wang, X. G., Wang, X. Y., Wang, Y., Wang, Y. D., Wang, Y. J., Wang, Z. H., Wang, Z. X., Wang, Zhen, Wang, Zheng, Wei, D. M., Wei, J. J., Wei, Y. J., Wen, T., Wu, C. Y., Wu, H. R., Wu, S., Wu, X. F., Wu, Y. S., Xi, S. Q., Xia, J., Xia, J. J., Xiang, G. M., Xiao, D. X., Xiao, G., Xin, G. G., Xin, Y. L., Xing, Y., Xiong, Z., Xu, D. L., Xu, R. F., Xu, R. X., Xu, W. L., Xue, L., Yan, D. H., Yan, J. Z., Yan, T., Yang, C. W., Yang, F., Yang, F. F., Yang, H. W., Yang, J. Y., Yang, L. L., Yang, M. J., Yang, R. Z., Yang, S. B., Yao, Y. H., Yao, Z. G., Ye, Y. M., Yin, L. Q., Yin, N., You, X. H., You, Z. Y., Yu, Y. H., Yuan, Q., Yue, H., Zeng, H. D., Zeng, T. X., Zeng, W., Zha, M., Zhang, B. B., Zhang, F., Zhang, H. M., Zhang, H. Y., Zhang, J. L., Zhang, L. X., Zhang, Li, Zhang, P. F., Zhang, P. P., Zhang, R., Zhang, S. B., Zhang, S. R., Zhang, S. S., Zhang, X., Zhang, X. P., Zhang, Y. F., Zhang, Yi, Zhang, Yong, Zhao, B., Zhao, J., Zhao, L., Zhao, L. Z., Zhao, S. P., Zheng, F., Zhou, B., Zhou, H., Zhou, J. N., Zhou, M., Zhou, P., Zhou, R., Zhou, X. X., Zhu, C. G., Zhu, F. R., Zhu, H., Zhu, K. J., and Zuo., X.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The Water Cherenkov Detector Array (WCDA) is one of the components of Large High Altitude Air Shower Observatory (LHAASO) and can monitor any sources over two-thirds of the sky for up to 7 hours per day with >98\% duty cycle. In this work, we report the detection of two outbursts of the Fanaroff-Riley I radio galaxy NGC 1275 that were detected by LHAASO-WCDA between November 2022 and January 2023 with statistical significance of 5.2~$\sigma$ and 8.3~$\sigma$. The observed spectral energy distribution in the range from 500 GeV to 3 TeV is fitted by a power-law with a best-fit spectral index of $\alpha=-3.37\pm0.52$ and $-3.35\pm0.29$, respectively. The outburst flux above 0.5~TeV was ($4.55\pm 4.21)\times~10^{-11}~\rm cm^{-2}~s^{-1}$ and ($3.45\pm 1.78)\times~10^{-11}~\rm cm^{-2}~s^{-1}$, corresponding to 60\%, 45\% of Crab Nebula flux. Variation analysis reveals the variability time-scale of days at the TeV energy band. A simple test by one-zone synchrotron self-Compton model reproduces the data in the gamma-ray band well., Comment: 11 pages, 8 figures, 3 tables
Published: 2024

2. LHAASO detection of very-high-energy gamma-ray emission surrounding PSR J0248+6021

Author: Cao, Zhen, Aharonian, F., An, Q., Axikegu, Bai, Y. X., Bao, Y. W., Bastieri, D., Bi, X. J., Bi, Y. J., Cai, J. T., Cao, Q., Cao, W. Y., Cao, Zhe, Chang, J., Chang, J. F., Chen, A. M., Chen, E. S., Chen, Liang, Chen, Lin, Chen, Long, Chen, M. J., Chen, M. L., Chen, Q. H., Chen, S. H., Chen, S. Z., Chen, T. L., Chen, Y., Cheng, N., Cheng, Y. D., Cui, M. Y., Cui, S. W., Cui, X. H., Cui, Y. D., Dai, B. Z., Dai, H. L., Dai, Z. G., Danzengluobu, Dong, X. Q., Duan, K. K., Fan, J. H., Fan, Y. Z., Fang, J., Fang, K., Feng, C. F., Feng, L., Feng, S. H., Feng, X. T., Feng, Y. L., Gabici, S., Gao, B., Gao, C. D., Gao, L. Q., Gao, Q., Gao, W., Gao, W. K., Ge, M. M., Geng, L. S., Giacinti, G., Gong, G. H., Gou, Q. B., Gu, M. H., Guo, F. L., Guo, X. L., Guo, Y. Q., Guo, Y. Y., Han, Y. A., He, H. H., He, H. N., He, J. Y., He, X. B., He, Y., Hor, Y. K., Hou, B. W., Hou, C., Hou, X., Hu, H. B., Hu, Q., Hu, S. C., Huang, D. H., Huang, T. Q., Huang, W. J., Huang, X. T., Huang, X. Y., Huang, Y., Huang, Z. C., Ji, X. L., Jia, H. Y., Jia, K., Jiang, K., Jiang, X. W., Jiang, Z. J., Jin, M., Kang, M. M., Ke, T., Kuleshov, D., Kurinov, K., Li, B. B., Li, Cheng, Li, Cong, Li, D., Li, F., Li, H. B., Li, H. C., Li, H. Y., Li, J., Li, Jian, Li, Jie, Li, K., Li, W. L., Li, X. R., Li, Xin, Li, Y. Z., Li, Zhe, Li, Zhuo, Liang, E. W., Liang, Y. F., Lin, J., Liu, B., Liu, C., Liu, D., Liu, H., Liu, H. D., Liu, J., Liu, J. L., Liu, J. Y., Liu, M. Y., Liu, R. Y., Liu, S. M., Liu, W., Liu, Y., Liu, Y. N., Lu, R., Luo, Q., Lv, H. K., Ma, B. Q., Ma, L. L., Ma, X. H., Mao, J. R., Min, Z., Mitthumsiri, W., Mu, H. J., Nan, Y. C., Neronov, A., Ou, Z. W., Pang, B. Y., Pattarakijwanich, P., Pei, Z. Y., Qi, M. Y., Qi, Y. Q., Qiao, B. Q., Qin, J. J., Ruffolo, D., Sáiz, A., Semikoz, D., Shao, C. Y., Shao, L., Shchegolev, O., Sheng, X. D., Shu, F. W., Song, H. C., Stenkin, Yu. V., Stepanov, V., Su, Y., Sun, Q. N., Sun, X. N., Sun, Z. B., Tam, P. H. T., Tang, Q. W., Tang, Z. B., Tian, W. W., Wang, C., Wang, C. B., Wang, G. W., Wang, H. G., Wang, H. H., Wang, J. C., Wang, K., Wang, L. P., Wang, L. Y., Wang, P. H., Wang, R., Wang, W., Wang, X. G., Wang, X. Y., Wang, Y., Wang, Y. D., Wang, Y. J., Wang, Z. H., Wang, Z. X., Wang, Zhen, Wang, Zheng, Wei, D. M., Wei, J. J., Wei, Y. J., Wen, T., Wu, C. Y., Wu, H. R., Wu, S., Wu, X. F., Wu, Y. S., Xi, S. Q., Xia, J., Xia, J. J., Xiang, G. M., Xiao, D. X., Xiao, G., Xin, G. G., Xin, Y. L., Xing, Y., Xiong, Z., Xu, D. L., Xu, R. F., Xu, R. X., Xu, W. L., Xue, L., Yan, D. H., Yan, J. Z., Yan, T., Yang, C. W., Yang, F., Yang, F. F., Yang, H. W., Yang, J. Y., Yang, L. L., Yang, M. J., Yang, R. Z., Yang, S. B., Yao, Y. H., Yao, Z. G., Ye, Y. M., Yin, L. Q., Yin, N., You, X. H., You, Z. Y., Yu, Y. H., Yuan, Q., Yue, H., Zeng, H. D., Zeng, T. X., Zeng, W., Zha, M., Zhang, B. B., Zhang, F., Zhang, H. M., Zhang, H. Y., Zhang, J. L., Zhang, L. X., Zhang, Li, Zhang, P. F., Zhang, P. P., Zhang, R., Zhang, S. B., Zhang, S. R., Zhang, S. S., Zhang, X., Zhang, X. P., Zhang, Y. F., Zhang, Yi, Zhang, Yong, Zhao, B., Zhao, J., Zhao, L., Zhao, L. Z., Zhao, S. P., Zheng, F., Zheng, J. H., Zhou, B., Zhou, H., Zhou, J. N., Zhou, M., Zhou, P., Zhou, R., Zhou, X. X., Zhu, C. G., Zhu, F. R., Zhu, H., Zhu, K. J., Zou, Y. C., and Zuo, X.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We report the detection of an extended very-high-energy (VHE) gamma-ray source coincident with the location of middle-aged (62.4~\rm kyr) pulsar PSR J0248+6021, by using the LHAASO-WCDA data of live 796 days and LHAASO-KM2A data of live 1216 days. A significant excess of \gray induced showers is observed both by WCDA in energy bands of 1-25~\rm TeV and KM2A in energy bands of $>$ 25~\rm TeV with 7.3 $\sigma$ and 13.5 $\sigma$, respectively. The best-fit position derived through WCDA data is R.A. = 42.06$^\circ \pm$ 0.12$^\circ$ and Dec. = 60.24$^\circ \pm $ 0.13$^\circ$ with an extension of 0.69$^\circ\pm$0.15$^\circ$ and that of the KM2A data is R.A.= 42.29$^\circ \pm $ 0.13$^\circ$ and Dec. = 60.38$^\circ \pm$ 0.07$^\circ$ with an extension of 0.37$^\circ\pm$0.07$^\circ$. No clear extended multiwavelength counterpart of this LHAASO source has been found from the radio band to the GeV band. The most plausible explanation of the VHE \gray emission is the inverse Compton process of highly relativistic electrons and positrons injected by the pulsar. These electrons/positrons are hypothesized to be either confined within the pulsar wind nebula or to have already escaped into the interstellar medium, forming a pulsar halo., Comment: 12 pages, 10 figures, Accepted by Sci. China-Phys. Mech. Astron
Published: 2024

3. Constraints on Ultra Heavy Dark Matter Properties from Dwarf Spheroidal Galaxies with LHAASO Observations

Author: Cao, Zhen, Aharonian, F., An, Q., Axikegu, Bai, Y. X., Bao, Y. W., Bastieri, D., Bi, X. J., Bi, Y. J., Cai, J. T., Cao, Q., Cao, W. Y., Cao, Zhe, Chang, J., Chang, J. F., Chen, A. M., Chen, E. S., Chen, Liang, Chen, Lin, Chen, Long, Chen, M. J., Chen, M. L., Chen, Q. H., Chen, S. H., Chen, S. Z., Chen, T. L., Chen, Y., Cheng, N., Cheng, Y. D., Cui, M. Y., Cui, S. W., Cui, X. H., Cui, Y. D., Dai, B. Z., Dai, H. L., Dai, Z. G., Danzengluobu, della Volpe, D., Dong, X. Q., Duan, K. K., Fan, J. H., Fan, Y. Z., Fang, J., Fang, K., Feng, C. F., Feng, L., Feng, S. H., Feng, X. T., Feng, Y. L., Gabici, S., Gao, B., Gao, C. D., Gao, L. Q., Gao, Q., Gao, W., Gao, W. K., Ge, M. M., Geng, L. S., Giacinti, G., Gong, G. H., Gou, Q. B., Gu, M. H., Guo, F. L., Guo, X. L., Guo, Y. Q., Guo, Y. Y., Han, Y. A., He, H. H., He, H. N., He, J. Y., He, X. B., He, Y., Heller, M., Hor, Y. K., Hou, B. W., Hou, C., Hou, X., Hu, H. B., Hu, Q., Hu, S. C., Huang, D. H., Huang, T. Q., Huang, W. J., Huang, X. T., Huang, X. Y., Huang, Y., Huang, Z. C., Ji, X. L., Jia, H. Y., Jia, K., Jiang, K., Jiang, X. W., Jiang, Z. J., Jin, M., Kang, M. M., Ke, T., Kuleshov, D., Kurinov, K., Li, B. B., Li, Cheng, Li, Cong, Li, D., Li, F., Li, H. B., Li, H. C., Li, H. Y., Li, J., Li, Jian, Li, Jie, Li, K., Li, W. L., Li, X. R., Li, Xin, Li, Y. Z., Li, Zhe, Li, Zhuo, Liang, E. W., Liang, Y. F., Lin, S. J., Liu, B., Liu, C., Liu, D., Liu, H., Liu, H. D., Liu, J., Liu, J. L., Liu, J. Y., Liu, M. Y., Liu, R. Y., Liu, S. M., Liu, W., Liu, Y., Liu, Y. N., Lu, R., Luo, Q., Lv, H. K., Ma, B. Q., Ma, L. L., Ma, X. H., Mao, J. R., Min, Z., Mitthumsiri, W., Mu, H. J., Nan, Y. C., Neronov, A., Ou, Z. W., Pang, B. Y., Pattarakijwanich, P., Pei, Z. Y., Qi, M. Y., Qi, Y. Q., Qiao, B. Q., Qin, J. J., Ruffolo, D., Saiz, A., Semikoz, D., Shao, C. Y., Shao, L., Shchegolev, O., Sheng, X. D., Shu, F. W., Song, H. C., Stenkin, Yu. V., Stepanov, V., Su, Y., Sun, Q. N., Sun, X. N., Sun, Z. B., Tam, P. H. T., Tang, Q. W., Tang, Z. B., Tian, W. W., Wang, C., Wang, C. B., Wang, G. W., Wang, H. G., Wang, H. H., Wang, J. C., Wang, K., Wang, L. P., Wang, L. Y., Wang, P. H., Wang, R., Wang, W., Wang, X. G., Wang, X. Y., Wang, Y., Wang, Y. D., Wang, Y. J., Wang, Z. H., Wang, Z. X., Wang, Zhen, Wang, Zheng, Wei, D. M., Wei, J. J., Wei, Y. J., Wen, T., Wu, C. Y., Wu, H. R., Wu, S., Wu, X. F., Wu, Y. S., Xi, S. Q., Xia, J., Xia, J. J., Xiang, G. M., Xiao, D. X., Xiao, G., Xin, G. G., Xin, Y. L., Xing, Y., Xiong, Z., Xu, D. L., Xu, R. F., Xu, R. X., Xu, W. L., Xue, L., Yan, D. H., Yan, J. Z., Yan, T., Yang, C. W., Yang, F., Yang, F. F., Yang, H. W., Yang, J. Y., Yang, L. L., Yang, M. J., Yang, R. Z., Yang, S. B., Yao, Y. H., Yao, Z. G., Ye, Y. M., Yin, L. Q., Yin, N., You, X. H., You, Z. Y., Yu, Y. H., Yuan, Q., Yue, H., Zeng, H. D., Zeng, T. X., Zeng, W., Zha, M., Zhang, B. B., Zhang, F., Zhang, H. M., Zhang, H. Y., Zhang, J. L., Zhang, L. X., Zhang, Li, Zhang, P. F., Zhang, P. P., Zhang, R., Zhang, S. B., Zhang, S. R., Zhang, S. S., Zhang, X., Zhang, X. P., Zhang, Y. F., Zhang, Yi, Zhang, Yong, Zhao, B., Zhao, J., Zhao, L., Zhao, L. Z., Zhao, S. P., Zheng, F., Zhou, B., Zhou, H., Zhou, J. N., Zhou, M., Zhou, P., Zhou, R., Zhou, X. X., Zhu, C. G., Zhu, F. R., Zhu, H., Zhu, K. J., and Zuo, X.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, High Energy Physics - Phenomenology
Abstract: In this work we try to search for signals generated by ultra-heavy dark matter at the Large High Altitude Air Shower Observatory (LHAASO) data. We look for possible gamma-ray by dark matter annihilation or decay from 16 dwarf spheroidal galaxies in the field of view of LHAASO. Dwarf spheroidal galaxies are among the most promising targets for indirect detection of dark matter which have low fluxes of astrophysical $\gamma$-ray background while large amount of dark matter. By analyzing more than 700 days observational data at LHAASO, no significant dark matter signal from 1 TeV to 1 EeV is detected. Accordingly we derive the most stringent constraints on the ultra-heavy dark matter annihilation cross-section up to EeV. The constraints on the lifetime of dark matter in decay mode are also derived., Comment: 17 pages, 12 figures, accepted by PRL
Published: 2024

4. Discovery of Very-high-energy Gamma-ray Emissions from the Low Luminosity AGN NGC 4278 by LHAASO

Author: Cao, Zhen, Aharonian, F., An, Q., Axikegu, Bai, Y. X., Bao, Y. W., Bastieri, D., Bi, X. J., Bi, Y. J., Cai, J. T., Cao, Q., Cao, W. Y., Cao, Zhe, Chang, J., Chang, J. F., Chen, A. M., Chen, E. S., Chen, Liang, Chen, Lin, Chen, Long, Chen, M. J., Chen, M. L., Chen, Q. H., Chen, S. H., Chen, S. Z., Chen, T. L., Chen, Y., Cheng, N., Cheng, Y. D., Cui, M. Y., Cui, S. W., Cui, X. H., Cui, Y. D., Dai, B. Z., Dai, H. L., Dai, Z. G., Danzengluobu, Dong, X. Q., Duan, K. K., Fan, J. H., Fan, Y. Z., Fang, J., Fang, K., Feng, C. F., Feng, L., Feng, S. H., Feng, X. T., Feng, Y. L., Gabici, S., Gao, B., Gao, C. D., Gao, L. Q., Gao, Q., Gao, W., Gao, W. K., Ge, M. M., Geng, L. S., Giacinti, G., Gong, G. H., Gou, Q. B., Gu, M. H., Guo, F. L., Guo, X. L., Guo, Y. Q., Guo, Y. Y., Han, Y. A., He, H. H., He, H. N., He, J. Y., He, X. B., He, Y., Hor, Y. K., Hou, B. W., Hou, C., Hou, X., Hu, H. B., Hu, Q., Hu, S. C., Huang, D. H., Huang, T. Q., Huang, W. J., Huang, X. T., Huang, X. Y., Huang, Y., Huang, Z. C., Ji, X. L., Jia, H. Y., Jia, K., Jiang, K., Jiang, X. W., Jiang, Z. J., Jin, M., Kang, M. M., Ke, T., Kuleshov, D., Kurinov, K., Li, B. B., Li, Cheng, Li, Cong, Li, D., Li, F., Li, H. B., Li, H. C., Li, H. Y., Li, J., Li, Jian, Li, Jie, Li, K., Li, W. L., Li, X. R., Li, Xin, Li, Y. Z., Li, Zhe, Li, Zhuo, Liang, E. W., Liang, Y. F., Lin, J., Liu, B., Liu, C., Liu, D., Liu, H., Liu, H. D., Liu, J., Liu, J. L., Liu, J. Y., Liu, M. Y., Liu, R. Y., Liu, S. M., Liu, W., Liu, Y., Liu, Y. N., Lu, R., Luo, Q., Lv, H. K., Ma, B. Q., Ma, L. L., Ma, X. H., Mao, J. R., Min, Z., Mitthumsiri, W., Mu, H. J., Nan, Y. C., Neronov, A., Ou, Z. W., Pang, B. Y., Pattarakijwanich, P., Pei, Z. Y., Qi, M. Y., Qi, Y. Q., Qiao, B. Q., Qin, J. J., Ruffolo, D., Sáiz, A., Semikoz, D., Shao, C. Y., Shao, L., Shchegolev, O., Sheng, X. D., Shu, F. W., Song, H. C., Stenkin, Yu. V., Stepanov, V., Su, Y., Sun, Q. N., Sun, X. N., Sun, Z. B., Tam, P. H. T., Tang, Q. W., Tang, Z. B., Tian, W. W., Wang, C., Wang, C. B., Wang, G. W., Wang, H. G., Wang, H. H., Wang, J. C., Wang, K., Wang, L. P., Wang, L. Y., Wang, P. H., Wang, R., Wang, W., Wang, X. G., Wang, X. Y., Wang, Y., Wang, Y. D., Wang, Y. J., Wang, Z. H., Wang, Z. X., Wang, Zhen, Wang, Zheng, Wei, D. M., Wei, J. J., Wei, Y. J., Wen, T., Wu, C. Y., Wu, H. R., Wu, S., Wu, X. F., Wu, Y. S., Xi, S. Q., Xia, J., Xia, J. J., Xiang, G. M., Xiao, D. X., Xiao, G., Xin, G. G., Xin, Y. L., Xing, Y., Xiong, Z., Xu, D. L., Xu, R. F., Xu, R. X., Xu, W. L., Xue, L., Yan, D. H., Yan, J. Z., Yan, T., Yang, C. W., Yang, F., Yang, F. F., Yang, H. W., Yang, J. Y., Yang, L. L., Yang, M. J., Yang, R. Z., Yang, S. B., Yao, Y. H., Yao, Z. G., Ye, Y. M., Yin, L. Q., Yin, N., You, X. H., You, Z. Y., Yu, Y. H., Yuan, Q., Yue, H., Zeng, H. D., Zeng, T. X., Zeng, W., Zha, M., Zhang, B. B., Zhang, F., Zhang, H. M., Zhang, H. Y., Zhang, J. L., Zhang, L. X., Zhang, Li, Zhang, P. F., Zhang, P. P., Zhang, R., Zhang, S. B., Zhang, S. R., Zhang, S. S., Zhang, X., Zhang, X. P., Zhang, Y. F., Zhang, Yi, Zhang, Yong, Zhao, B., Zhao, J., Zhao, L., Zhao, L. Z., Zhao, S. P., Zheng, F., Zheng, J. H., Zhou, B., Zhou, H., Zhou, J. N., Zhou, M., Zhou, P., Zhou, R., Zhou, X. X., Zhu, C. G., Zhu, F. R., Zhu, H., Zhu, K. J., Zou, Y. C., and Zuo, X.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The first source catalog of Large High Altitude Air Shower Observatory reported the detection of a very-high-energy gamma ray source, 1LHAASO J1219+2915. In this paper a further detailed study of the spectral and temporal behavior of this point-like source have been carried. The best-fit position of the TeV source ($\rm{RA}=185.05^{\circ}\pm0.04^{\circ}$, $\rm{Dec}=29.25^{\circ}\pm0.03^{\circ}$) is compatible with NGC 4278 within $\sim0.03$ degree. Variation analysis shows an indication of the variability at a few months level in the TeV band, which is consistent with low frequency observations. Based on these observations, we report the detection of TeV $\gamma$-ray emissions from this low-luminosity AGN NGC 4278. The observations by LHAASO-WCDA during active period has a significance level of 8.8\,$\sigma$ with best-fit photon spectral index $\varGamma=2.56\pm0.14$ and a flux $f_{1-10\,\rm{TeV}}=(7.0\pm1.1_{\rm{sta}}\pm0.35_{\rm{syst}})\times10^{-13}\,\rm{photons\,cm^{-2}\,s^{-1}}$, or approximately $5\%$ of the Crab Nebula. The discovery of VHE from NGC 4278 indicates that the compact, weak radio jet can efficiently accelerate particles and emit TeV photons., Comment: 11 pages, 5 figures
Published: 2024

5. LHAASO-KM2A detector simulation using Geant4

Author: Cao, Zhen, Aharonian, F., An, Q., Axikegu, Bai, Y. X., Bao, Y. W., Bastieri, D., Bi, X. J., Bi, Y. J., Cai, J. T., Cao, Q., Cao, W. Y., Cao, Zhe, Chang, J., Chang, J. F., Chen, A. M., Chen, E. S., Chen, Liang, Chen, Lin, Chen, Long, Chen, M. J., Chen, M. L., Chen, Q. H., Chen, S. H., Chen, S. Z., Chen, T. L., Chen, Y., Cheng, N., Cheng, Y. D., Cui, M. Y., Cui, S. W., Cui, X. H., Cui, Y. D., Dai, B. Z., Dai, H. L., Dai, Z. G., Danzengluobu, Dong, X. Q., Duan, K. K., Fan, J. H., Fan, Y. Z., Fang, J., Fang, K., Feng, C. F., Feng, L., Feng, S. H., Feng, X. T., Feng, Y. L., Gabici, S., Gao, B., Gao, C. D., Gao, L. Q., Gao, Q., Gao, W., Gao, W. K., Ge, M. M., Geng, L. S., Giacinti, G., Gong, G. H., Gou, Q. B., Gu, M. H., Guo, F. L., Guo, X. L., Guo, Y. Q., Guo, Y. Y., Han, Y. A., He, H. H., He, H. N., He, J. Y., He, X. B., He, Y., Hor, Y. K., Hou, B. W., Hou, C., Hou, X., Hu, H. B., Hu, Q., Hu, S. C., Huang, D. H., Huang, T. Q., Huang, W. J., Huang, X. T., Huang, X. Y., Huang, Y., Huang, Z. C., Ji, X. L., Jia, H. Y., Jia, K., Jiang, K., Jiang, X. W., Jiang, Z. J., Jin, M., Kang, M. M., Ke, T., Kuleshov, D., Kurinov, K., Li, B. B., Li, Cheng, Li, Cong, Li, D., Li, F., Li, H. B., Li, H. C., Li, H. Y., Li, J., Li, Jian, Li, Jie, Li, K., Li, W. L., Li, X. R., Li, Xin, Li, Y. Z., Li, Zhe, Li, Zhuo, Liang, E. W., Liang, Y. F., Lin, J., Liu, B., Liu, C., Liu, D., Liu, H., Liu, H. D., Liu, J., Liu, J. L., Liu, J. Y., Liu, M. Y., Liu, R. Y., Liu, S. M., Liu, W., Liu, Y., Liu, Y. N., Lu, R., Luo, Q., Lv, H. K., Ma, B. Q., Ma, L. L., Ma, X. H., Mao, J. R., Min, Z., Mitthumsiri, W., Mu, H. J., Nan, Y. C., Neronov, A., Ou, Z. W., Pang, B. Y., Pattarakijwanich, P., Pei, Z. Y., Qi, M. Y., Qi, Y. Q., Qiao, B. Q., Qin, J. J., Ruffolo, D., Sáiz, A., Semikoz, D., Shao, C. Y., Shao, L., Shchegolev, O., Sheng, X. D., Shu, F. W., Song, H. C., Stenkin, Yu. V., Stepanov, V., Su, Y., Sun, Q. N., Sun, X. N., Sun, Z. B., Tam, P. H. T., Tang, Q. W., Tang, Z. B., Tian, W. W., Wang, C., Wang, C. B., Wang, G. W., Wang, H. G., Wang, H. H., Wang, J. C., Wang, K., Wang, L. P., Wang, L. Y., Wang, P. H., Wang, R., Wang, W., Wang, X. G., Wang, X. Y., Wang, Y., Wang, Y. D., Wang, Y. J., Wang, Z. H., Wang, Z. X., Wang, Zhen, Wang, Zheng, Wei, D. M., Wei, J. J., Wei, Y. J., Wen, T., Wu, C. Y., Wu, H. R., Wu, S., Wu, X. F., Wu, Y. S., Xi, S. Q., Xia, J., Xia, J. J., Xiang, G. M., Xiao, D. X., Xiao, G., Xin, G. G., Xin, Y. L., Xing, Y., Xiong, Z., Xu, D. L., Xu, R. F., Xu, R. X., Xu, W. L., Xue, L., Yan, D. H., Yan, J. Z., Yan, T., Yang, C. W., Yang, F., Yang, F. F., Yang, H. W., Yang, J. Y., Yang, L. L., Yang, M. J., Yang, R. Z., Yang, S. B., Yao, Y. H., Yao, Z. G., Ye, Y. M., Yin, L. Q., Yin, N., You, X. H., You, Z. Y., Yu, Y. H., Yuan, Q., Yue, H., Zeng, H. D., Zeng, T. X., Zeng, W., Zha, M., Zhang, B. B., Zhang, F., Zhang, H. M., Zhang, H. Y., Zhang, J. L., Zhang, L. X., Zhang, Li, Zhang, P. F., Zhang, P. P., Zhang, R., Zhang, S. B., Zhang, S. R., Zhang, S. S., Zhang, X., Zhang, X. P., Zhang, Y. F., Zhang, Yi, Zhang, Yong, Zhao, B., Zhao, J., Zhao, L., Zhao, L. Z., Zhao, S. P., Zheng, F., Zheng, J. H., Zhou, B., Zhou, H., Zhou, J. N., Zhou, M., Zhou, P., Zhou, R., Zhou, X. X., Zhu, C. G., Zhu, F. R., Zhu, H., Zhu, K. J., and Zuo, X.
Subjects: Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract: KM2A is one of the main sub-arrays of LHAASO, working on gamma ray astronomy and cosmic ray physics at energies above 10 TeV. Detector simulation is the important foundation for estimating detector performance and data analysis. It is a big challenge to simulate the KM2A detector in the framework of Geant4 due to the need to track numerous photons from a large number of detector units (>6000) with large altitude difference (30 m) and huge coverage (1.3 km^2). In this paper, the design of the KM2A simulation code G4KM2A based on Geant4 is introduced. The process of G4KM2A is optimized mainly in memory consumption to avoid memory overffow. Some simpliffcations are used to signiffcantly speed up the execution of G4KM2A. The running time is reduced by at least 30 times compared to full detector simulation. The particle distributions and the core/angle resolution comparison between simulation and experimental data of the full KM2A array are also presented, which show good agreement.
Published: 2024
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6. Measurements of All-Particle Energy Spectrum and Mean Logarithmic Mass of Cosmic Rays from 0.3 to 30 PeV with LHAASO-KM2A

Author: The LHAASO Collaboration, Cao, Zhen, Aharonian, F., An, Q., Axikegu, A., Bai, Y. X., Bao, Y. W., Bastieri, D., Bi, X. J., Bi, Y. J., Cai, J. T., Cao, Q., Cao, W. Y., Cao, Zhe, Chang, J., Chang, J. F., Chen, A. M., Chen, E. S., Chen, Liang, Chen, Lin, Chen, Long, Chen, M. J., Chen, M. L., Chen, Q. H., Chen, S. H., Chen, S. Z., Chen, T. L., Chen, Y., Cheng, N., Cheng, Y. D., Cui, M. Y., Cui, S. W., Cui, X. H., Cui, Y. D., Dai, B. Z., Dai, H. L., Dai, Z. G., Danzengluobu, della Volpe, D., Dong, X. Q., Duan, K. K., Fan, J. H., Fan, Y. Z., Fang, J., Fang, K., Feng, C. F., Feng, L., Feng, S. H., Feng, X. T., Feng, Y. L., Gabici, S., Gao, B., Gao, C. D., Gao, L. Q., Gao, Q., Gao, W., Gao, W. K., Ge, M. M., Geng, L. S., Giacinti, G., Gong, G. H., Gou, Q. B., Gu, M. H., Guo, F. L., Guo, X. L., Guo, Y. Q., Guo, Y. Y., Han, Y. A., He, H. H., He, H. N., He, J. Y., He, X. B., He, Y., Heller, M., Hor, Y. K., Hou, B. W., Hou, C., Hou, X., Hu, H. B., Hu, Q., Hu, S. C., Huang, D. H., Huang, T. Q., Huang, W. J., Huang, X. T., Huang, X. Y., Huang, Y., Huang, Z. C., Ji, X. L., Jia, H. Y., Jia, K., Jiang, K., Jiang, X. W., Jiang, Z. J., Jin, M., Kang, M. M., Ke, T., Kuleshov, D., Kurinov, K., Li, B. B., Li, Cheng, Li, Cong, Li, D., Li, F., Li, H. B., Li, H. C., Li, H. Y., Li, J., Li, Jian, Li, Jie, Li, K., Li, W. L., Li, X. R., Li, Xin, Li, Y. Z., Li, Zhe, Li, Zhuo, Liang, E. W., Liang, Y. F., Lin, S. J., Liu, B., Liu, C., Liu, D., Liu, H., Liu, H. D., Liu, J., Liu, J. L., Liu, J. Y., Liu, M. Y., Liu, R. Y., Liu, S. M., Liu, W., Liu, Y., Liu, Y. N., Lu, R., Luo, Q., Lv, H. K., Ma, B. Q., Ma, L. L., Ma, X. H., Mao, J. R., Min, Z., Mitthumsiri, W., Mu, H. J., Nan, Y. C., Neronov, A., Ou, Z. W., Pang, B. Y., Pattarakijwanich, P., Pei, Z. Y., Qi, M. Y., Qi, Y. Q., Qiao, B. Q., Qin, J. J., Ruffolo, D., Sáiz, A., Semikoz, D., Shao, C. Y., Shao, L., Shchegolev, O., Sheng, X. D., Shu, F. W., Song, H. C., Stenkin, Yu. V., Stepanov, V., Su, Y., Sun, Q. N., Sun, X. N., Sun, Z. B., Tam, P. H. T., Tang, Q. W., Tang, Z. B., Tian, W. W., Wang, C., Wang, C. B., Wang, G. W., Wang, H. G., Wang, H. H., Wang, J. C., Wang, K., Wang, L. P., Wang, L. Y., Wang, P. H., Wang, R., Wang, W., Wang, X. G., Wang, X. Y., Wang, Y., Wang, Y. D., Wang, Y. J., Wang, Z. H., Wang, Z. X., Wang, Zhen, Wang, Zheng, Wei, D. M., Wei, J. J., Wei, Y. J., Wen, T., Wu, C. Y., Wu, H. R., Wu, S., Wu, X. F., Wu, Y. S., Xi, S. Q., Xia, J., Xia, J. J., Xiang, G. M., Xiao, D. X., Xiao, G., Xin, G. G., Xin, Y. L., Xing, Y., Xiong, Z., Xu, D. L., Xu, R. F., Xu, R. X., Xu, W. L., Xue, L., Yan, D. H., Yan, J. Z., Yan, T., Yang, C. W., Yang, F., Yang, F. F., Yang, H. W., Yang, J. Y., Yang, L. L., Yang, M. J., Yang, R. Z., Yang, S. B., Yao, Y. H., Yao, Z. G., Ye, Y. M., Yin, L. Q., Yin, N., You, X. H., You, Z. Y., Yu, Y. H., Yuan, Q., Yue, H., Zeng, H. D., Zeng, T. X., Zeng, W., Zha, M., Zhang, B. B., Zhang, F., Zhang, H. M., Zhang, H. Y., Zhang, J. L., Zhang, L. X., Zhang, Li, Zhang, P. F., Zhang, P. P., Zhang, R., Zhang, S. B., Zhang, S. R., Zhang, S. S., Zhang, X., Zhang, X. P., Zhang, Y. F., Zhang, Yi, Zhang, Yong, Zhao, B., Zhao, J., Zhao, L., Zhao, L. Z., Zhao, S. P., Zheng, F., Zhou, B., Zhou, H., Zhou, J. N., Zhou, M., Zhou, P., Zhou, R., Zhou, X. X., Zhu, C. G., Zhu, F. R., Zhu, H., Zhu, K. J., and Zuo, X.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We present the measurements of all-particle energy spectrum and mean logarithmic mass of cosmic rays in the energy range of 0.3-30 PeV using data collected from LHAASO-KM2A between September 2021 and December 2022, which is based on a nearly composition-independent energy reconstruction method, achieving unprecedented accuracy. Our analysis reveals the position of the knee at $3.67 \pm 0.05 \pm 0.15$ PeV. Below the knee, the spectral index is found to be -$2.7413 \pm 0.0004 \pm 0.0050$, while above the knee, it is -$3.128 \pm 0.005 \pm 0.027$, with the sharpness of the transition measured with a statistical error of 2%. The mean logarithmic mass of cosmic rays is almost heavier than helium in the whole measured energy range. It decreases from 1.7 at 0.3 PeV to 1.3 at 3 PeV, representing a 24% decline following a power law with an index of -$0.1200 \pm 0.0003 \pm 0.0341$. This is equivalent to an increase in abundance of light components. Above the knee, the mean logarithmic mass exhibits a power law trend towards heavier components, which is reversal to the behavior observed in the all-particle energy spectrum. Additionally, the knee position and the change in power-law index are approximately the same. These findings suggest that the knee observed in the all-particle spectrum corresponds to the knee of the light component, rather than the medium-heavy components., Comment: 8 pages, 3 figures
Published: 2024
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7. Does or did the supernova remnant Cassiopeia A operate as a PeVatron?

Author: Cao, Zhen, Aharonian, F., An, Q., Axikegu, Bai, Y. X., Bao, Y. W., Bastieri, D., Bi, X. J., Bi, Y. J., Cai, J. T., Cao, Q., Cao, W. Y., Cao, Zhe, Chang, J., Chang, J. F., Chen, A. M., Chen, E. S., Chen, Liang, Chen, Lin, Chen, Long, Chen, M. J., Chen, M. L., Chen, Q. H., Chen, S. H., Chen, S. Z., Chen, T. L., Chen, Y., Cheng, N., Cheng, Y. D., Cui, M. Y., Cui, S. W., Cui, X. H., Cui, Y. D., Dai, B. Z., Dai, H. L., Dai, Z. G., Danzengluobu, della Volpe, D., Dong, X. Q., Duan, K. K., Fan, J. H., Fan, Y. Z., Fang, J., Fang, K., Feng, C. F., Feng, L., Feng, S. H., Feng, X. T., Feng, Y. L., Gabici, S., Gao, B., Gao, C. D., Gao, L. Q., Gao, Q., Gao, W., Gao, W. K., Ge, M. M., Geng, L. S., Giacinti, G., Gong, G. H., Gou, Q. B., Gu, M. H., Guo, F. L., Guo, X. L., Guo, Y. Q., Guo, Y. Y., Han, Y. A., He, H. H., He, H. N., He, J. Y., He, X. B., He, Y., Heller, M., Hor, Y. K., Hou, B. W., Hou, C., Hou, X., Hu, H. B., Hu, Q., Hu, S. C., Huang, D. H., Huang, T. Q., Huang, W. J., Huang, X. T., Huang, X. Y., Huang, Y., Huang, Z. C., Ji, X. L., Jia, H. Y., Jia, K., Jiang, K., Jiang, X. W., Jiang, Z. J., Jin, M., Kang, M. M., Ke, T., Kuleshov, D., Kurinov, K., Li, B. B., Li, Cheng, Li, Cong, Li, D., Li, F., Li, H. B., Li, H. C., Li, H. Y., Li, J., Li, Jian, Li, Jie, Li, K., Li, W. L., Li, X. R., Li, Xin, Li, Y. Z., Li, Zhe, Li, Zhuo, Liang, E. W., Liang, Y. F., Lin, S. J., Liu, B., Liu, C., Liu, D., Liu, H., Liu, H. D., Liu, J., Liu, J. L., Liu, J. Y., Liu, M. Y., Liu, R. Y., Liu, S. M., Liu, W., Liu, Y., Liu, Y. N., Lu, R., Luo, Q., Lv, H. K., Ma, B. Q., Ma, L. L., Ma, X. H., Mao, J. R., Min, Z., Mitthumsiri, W., Mu, H. J., Nan, Y. C., Neronov, A., Ou, Z. W., Pang, B. Y., Pattarakijwanich, P., Pei, Z. Y., Qi, M. Y., Qi, Y. Q., Qiao, B. Q., Qin, J. J., Ruffolo, D., Sáiz, A., Semikoz, D., Shao, C. Y., Shao, L., Shchegolev, O., Sheng, X. D., Shu, F. W., Song, H. C., Stenkin, Yu. V., Stepanov, V., Su, Y., Sun, Q. N., Sun, X. N., Sun, Z. B., Tam, P. H. T., Tang, Q. W., Tang, Z. B., Tian, W. W., Wang, C., Wang, C. B., Wang, G. W., Wang, H. G., Wang, H. H., Wang, J. C., Wang, K., Wang, L. P., Wang, L. Y., Wang, P. H., Wang, R., Wang, W., Wang, X. G., Wang, X. Y., Wang, Y., Wang, Y. D., Wang, Y. J., Wang, Z. H., Wang, Z. X., Wang, Zhen, Wang, Zheng, Wei, D. M., Wei, J. J., Wei, Y. J., Wen, T., Wu, C. Y., Wu, H. R., Wu, S., Wu, X. F., Wu, Y. S., Xi, S. Q., Xia, J., Xia, J. J., Xiang, G. M., Xiao, D. X., Xiao, G., Xin, G. G., Xin, Y. L., Xing, Y., Xiong, Z., Xu, D. L., Xu, R. F., Xu, R. X., Xu, W. L., Xue, L., Yan, D. H., Yan, J. Z., Yan, T., Yang, C. W., Yang, F., Yang, F. F., Yang, H. W., Yang, J. Y., Yang, L. L., Yang, M. J., Yang, R. Z., Yang, S. B., Yao, Y. H., Yao, Z. G., Ye, Y. M., Yin, L. Q., Yin, N., You, X. H., You, Z. Y., Yu, Y. H., Yuan, Q., Yue, H., Zeng, H. D., Zeng, T. X., Zeng, W., Zha, M., Zhang, B. B., Zhang, F., Zhang, H. M., Zhang, H. Y., Zhang, J. L., Zhang, L. X., Zhang, Li, Zhang, P. F., Zhang, P. P., Zhang, R., Zhang, S. B., Zhang, S. R., Zhang, S. S., Zhang, X., Zhang, X. P., Zhang, Y. F., Zhang, Yi, Zhang, Yong, Zhao, B., Zhao, J., Zhao, L., Zhao, L. Z., Zhao, S. P., Zheng, F., Zhou, B., Zhou, H., Zhou, J. N., Zhou, M., Zhou, P., Zhou, R., Zhou, X. X., Zhu, C. G., Zhu, F. R., Zhu, H., Zhu, K. J., and Zuo., X.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: For decades, supernova remnants (SNRs) have been considered the prime sources of Galactic Cosmic rays (CRs). But whether SNRs can accelerate CR protons to PeV energies and thus dominate CR flux up to the knee is currently under intensive theoretical and phenomenological debate. The direct test of the ability of SNRs to operate as CR PeVatrons can be provided by ultrahigh-energy (UHE; $E_\gamma \geq 100$~TeV) $\gamma$-rays. In this context, the historical SNR Cassiopeia A (Cas A) is considered one of the most promising target for UHE observations. This paper presents the observation of Cas A and its vicinity by the LHAASO KM2A detector. The exceptional sensitivity of LHAASO KM2A in the UHE band, combined with the young age of Cas A, enabled us to derive stringent model-independent limits on the energy budget of UHE protons and nuclei accelerated by Cas A at any epoch after the explosion. The results challenge the prevailing paradigm that Cas A-type SNRs are major suppliers of PeV CRs in the Milky Way., Comment: 11 pages, 3 figures, Accepted by the APJL
Published: 2023

8. Very high energy gamma-ray emission beyond 10 TeV from GRB 221009A

Author: Cao, Zhen, Aharonian, F., An, Q., Axikegu, A., Bai, Y. X., Bao, Y. W., Bastieri, D., Bi, X. J., Bi, Y. J., Cai, J. T., Cao, Q., Cao, W. Y., Cao, Zhe, Chang, J., Chang, J. F., Chen, A. M., Chen, E. S., Chen, Liang, Chen, Lin, Chen, Long, Chen, M. J., Chen, M. L., Chen, Q. H., Chen, S. H., Chen, S. Z., Chen, T. L., Chen, Y., Cheng, N., Cheng, Y. D., Cui, M. Y., Cui, S. W., Cui, X. H., Cui, Y. D., Dai, B. Z., Dai, H. L., Dai, Z. G., Danzengluobu, della Volpe, D., Dong, X. Q., Duan, K. K., Fan, J. H., Fan, Y. Z., Fang, J., Fang, K., Feng, C. F., Feng, L., Feng, S. H., Feng, X. T., Feng, Y. L., Gabici, S., Gao, B., Gao, C. D., Gao, L. Q., Gao, Q., Gao, W., Gao, W. K., Ge, M. M., Geng, L. S., Giacinti, G., Gong, G. H., Gou, Q. B., Gu, M. H., Guo, F. L., Guo, X. L., Guo, Y. Q., Guo, Y. Y., Han, Y. A., He, H. H., He, H. N., He, J. Y., He, X. B., He, Y., Heller, M., Hor, Y. K., Hou, B. W., Hou, C., Hou, X., Hu, H. B., Hu, Q., Hu, S. C., Huang, D. H., Huang, T. Q., Huang, W. J., Huang, X. T., Huang, X. Y., Huang, Y., Huang, Z. C., Ji, X. L., Jia, H. Y., Jia, K., Jiang, K., Jiang, X. W., Jiang, Z. J., Jin, M., Kang, M. M., Ke, T., Kuleshov, D., Kurinov, K., Li, B. B., Li, Cheng, Li, Cong, Li, D., Li, F., Li, H. B., Li, H. C., Li, H. Y., Li, J., Li, Jian, Li, Jie, Li, K., Li, W. L., Li, X. R., Li, Xin, Li, Y. Z., Li, Zhe, Li, Zhuo, Liang, E. W., Liang, Y. F., Lin, S. J., Liu, B., Liu, C., Liu, D., Liu, H., Liu, H. D., Liu, J., Liu, J. L., Liu, J. Y., Liu, M. Y., Liu, R. Y., Liu, S. M., Liu, W., Liu, Y., Liu, Y. N., Lu, R., Luo, Q., Lv, H. K., Ma, B. Q., Ma, L. L., Ma, X. H., Mao, J. R., Min, Z., Mitthumsiri, W., Mu, H. J., Nan, Y. C., Neronov, A., Ou, Z. W., Pang, B. Y., Pattarakijwanich, P., Pei, Z. Y., Qi, M. Y., Qi, Y. Q., Qiao, B. Q., Qin, J. J., Ruffolo, D., Sáiz, A., Semikoz, D., Shao, C. Y., Shao, L., Shchegolev, O., Sheng, X. D., Shu, F. W., Song, H. C., Stenkin, Yu. V., Stepanov, V., Su, Y., Sun, Q. N., Sun, X. N., Sun, Z. B., Tam, P. H. T., Tang, Q. W., Tang, Z. B., Tian, W. W., Wang, C., Wang, C. B., Wang, G. W., Wang, H. G., Wang, H. H., Wang, J. C., Wang, K., Wang, L. P., Wang, L. Y., Wang, P. H., Wang, R., Wang, W., Wang, X. G., Wang, X. Y., Wang, Y., Wang, Y. D., Wang, Y. J., Wang, Z. H., Wang, Z. X., Wang, Zhen, Wang, Zheng, Wei, D. M., Wei, J. J., Wei, Y. J., Wen, T., Wu, C. Y., Wu, H. R., Wu, S., Wu, X. F., Wu, Y. S., Xi, S. Q., Xia, J., Xia, J. J., Xiang, G. M., Xiao, D. X., Xiao, G., Xin, G. G., Xin, Y. L., Xing, Y., Xiong, Z., Xu, D. L., Xu, R. F., Xu, R. X., Xu, W. L., Xue, L., Yan, D. H., Yan, J. Z., Yan, T., Yang, C. W., Yang, F., Yang, F. F., Yang, H. W., Yang, J. Y., Yang, L. L., Yang, M. J., Yang, R. Z., Yang, S. B., Yao, Y. H., Yao, Z. G., Ye, Y. M., Yin, L. Q., Yin, N., You, X. H., You, Z. Y., Yu, Y. H., Yuan, Q., Yue, H., Zeng, H. D., Zeng, T. X., Zeng, W., Zha, M., Zhang, B. B., Zhang, F., Zhang, H. M., Zhang, H. Y., Zhang, J. L., Zhang, L. X., Zhang, Li, Zhang, P. F., Zhang, P. P., Zhang, R., Zhang, S. B., Zhang, S. R., Zhang, S. S., Zhang, X., Zhang, X. P., Zhang, Y. F., Zhang, Yi, Zhang, Yong, Zhao, B., Zhao, J., Zhao, L., Zhao, L. Z., Zhao, S. P., Zheng, F., Zhou, B., Zhou, H., Zhou, J. N., Zhou, M., Zhou, P., Zhou, R., Zhou, X. X., Zhu, C. G., Zhu, F. R., Zhu, H., Zhu, K. J., and Zuo, X.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The highest energy gamma-rays from gamma-ray bursts (GRBs) have important implications for their radiation mechanism. Here we report for the first time the detection of gamma-rays up to 13 TeV from the brightest GRB 221009A by the Large High Altitude Air-shower Observatory (LHAASO). The LHAASO-KM2A detector registered more than 140 gamma-rays with energies above 3 TeV during 230$-$900s after the trigger. The intrinsic energy spectrum of gamma-rays can be described by a power-law after correcting for extragalactic background light (EBL) absorption. Such a hard spectrum challenges the synchrotron self-Compton (SSC) scenario of relativistic electrons for the afterglow emission above several TeV. Observations of gamma-rays up to 13 TeV from a source with a measured redshift of z=0.151 hints more transparency in intergalactic space than previously expected. Alternatively, one may invoke new physics such as Lorentz Invariance Violation (LIV) or an axion origin of very high energy (VHE) signals., Comment: 49pages, 11figures
Published: 2023
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9. The First LHAASO Catalog of Gamma-Ray Sources

Author: Cao, Zhen, Aharonian, F., An, Q., Axikegu, Bai, Y. X., Bao, Y. W., Bastieri, D., Bi, X. J., Bi, Y. J., Cai, J. T., Cao, Q., Cao, W. Y., Cao, Zhe, Chang, J., Chang, J. F., Chen, A. M., Chen, E. S., Chen, Liang, Chen, Lin, Chen, Long, Chen, M. J., Chen, M. L., Chen, Q. H., Chen, S. H., Chen, S. Z., Chen, T. L., Chen, Y., Cheng, N., Cheng, Y. D., Cui, M. Y., Cui, S. W., Cui, X. H., Cui, Y. D., Dai, B. Z., Dai, H. L., Dai, Z. G., Danzengluobu, della Volpe, D., Dong, X. Q., Duan, K. K., Fan, J. H., Fan, Y. Z., Fang, J., Fang, K., Feng, C. F., Feng, L., Feng, S. H., Feng, X. T., Feng, Y. L., Gabici, S., Gao, B., Gao, C. D., Gao, L. Q., Gao, Q., Gao, W., Gao, W. K., Ge, M. M., Geng, L. S., Giacinti, G., Gong, G. H., Gou, Q. B., Gu, M. H., Guo, F. L., Guo, X. L., Guo, Y. Q., Guo, Y. Y., Han, Y. A., He, H. H., He, H. N., He, J. Y., He, X. B., He, Y., Heller, M., Hor, Y. K., Hou, B. W., Hou, C., Hou, X., Hu, H. B., Hu, Q., Hu, S. C., Huang, D. H., Huang, T. Q., Huang, W. J., Huang, X. T., Huang, X. Y., Huang, Y., Huang, Z. C., Ji, X. L., Jia, H. Y., Jia, K., Jiang, K., Jiang, X. W., Jiang, Z. J., Jin, M., Kang, M. M., Ke, T., Kuleshov, D., Kurinov, K., Li, B. B., Li, Cheng, Li, Cong, Li, D., Li, F., Li, H. B., Li, H. C., Li, H. Y., Li, J., Li, Jian, Li, Jie, Li, K., Li, W. L., Li, X. R., Li, Xin, Li, Y. Z., Li, Zhe, Li, Zhuo, Liang, E. W., Liang, Y. F., Lin, S. J., Liu, B., Liu, C., Liu, D., Liu, H., Liu, H. D., Liu, J., Liu, J. L., Liu, J. Y., Liu, M. Y., Liu, R. Y., Liu, S. M., Liu, W., Liu, Y., Liu, Y. N., Lu, R., Luo, Q., Lv, H. K., Ma, B. Q., Ma, L. L., Ma, X. H., Mao, J. R., Min, Z., Mitthumsiri, W., Mu, H. J., Nan, Y. C., Neronov, A., Ou, Z. W., Pang, B. Y., Pattarakijwanich, P., Pei, Z. Y., Qi, M. Y., Qi, Y. Q., Qiao, B. Q., Qin, J. J., Ruffolo, D., Sáiz, A., Semikoz, D., Shao, C. Y., Shao, L., Shchegolev, O., Sheng, X. D., Shu, F. W., Song, H. C., Stenkin, Yu. V., Stepanov, V., Su, Y., Sun, Q. N., Sun, X. N., Sun, Z. B., Tam, P. H. T., Tang, Q. W., Tang, Z. B., Tian, W. W., Wang, C., Wang, C. B., Wang, G. W., Wang, H. G., Wang, H. H., Wang, J. C., Wang, K., Wang, L. P., Wang, L. Y., Wang, P. H., Wang, R., Wang, W., Wang, X. G., Wang, X. Y., Wang, Y., Wang, Y. D., Wang, Y. J., Wang, Z. H., Wang, Z. X., Wang, Zhen, Wang, Zheng, Wei, D. M., Wei, J. J., Wei, Y. J., Wen, T., Wu, C. Y., Wu, H. R., Wu, S., Wu, X. F., Wu, Y. S., Xi, S. Q., Xia, J., Xia, J. J., Xiang, G. M., Xiao, D. X., Xiao, G., Xin, G. G., Xin, Y. L., Xing, Y., Xiong, Z., Xu, D. L., Xu, R. F., Xu, R. X., Xu, W. L., Xue, L., Yan, D. H., Yan, J. Z., Yan, T., Yang, C. W., Yang, F., Yang, F. F., Yang, H. W., Yang, J. Y., Yang, L. L., Yang, M. J., Yang, R. Z., Yang, S. B., Yao, Y. H., Yao, Z. G., Ye, Y. M., Yin, L. Q., Yin, N., You, X. H., You, Z. Y., Yu, Y. H., Yuan, Q., Yue, H., Zeng, H. D., Zeng, T. X., Zeng, W., Zha, M., Zhang, B. B., Zhang, F., Zhang, H. M., Zhang, H. Y., Zhang, J. L., Zhang, L. X., Zhang, Li, Zhang, P. F., Zhang, P. P., Zhang, R., Zhang, S. B., Zhang, S. R., Zhang, S. S., Zhang, X., Zhang, X. P., Zhang, Y. F., Zhang, Yi, Zhang, Yong, Zhao, B., Zhao, J., Zhao, L., Zhao, L. Z., Zhao, S. P., Zheng, F., Zhou, B., Zhou, H., Zhou, J. N., Zhou, M., Zhou, P., Zhou, R., Zhou, X. X., Zhu, C. G., Zhu, F. R., Zhu, H., Zhu, K. J., and Zuo., X.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, High Energy Physics - Phenomenology
Abstract: We present the first catalog of very-high energy and ultra-high energy gamma-ray sources detected by the Large High Altitude Air Shower Observatory (LHAASO). The catalog was compiled using 508 days of data collected by the Water Cherenkov Detector Array (WCDA) from March 2021 to September 2022 and 933 days of data recorded by the Kilometer Squared Array (KM2A) from January 2020 to September 2022. This catalog represents the main result from the most sensitive large coverage gamma-ray survey of the sky above 1 TeV, covering declination from $-$20$^{\circ}$ to 80$^{\circ}$. In total, the catalog contains 90 sources with an extended size smaller than $2^\circ$ and a significance of detection at $> 5\sigma$. Based on our source association criteria, 32 new TeV sources are proposed in this study. Among the 90 sources, 43 sources are detected with ultra-high energy ($E > 100$ TeV) emission at $> 4\sigma$ significance level. We provide the position, extension, and spectral characteristics of all the sources in this catalog., Comment: 40 pages, 13 figures, 4 tables
Published: 2023
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10. Measurement of ultra-high-energy diffuse gamma-ray emission of the Galactic plane from 10 TeV to 1 PeV with LHAASO-KM2A

Author: Cao, Zhen, Aharonian, F., An, Q., Axikegu, Bai, Y. X., Bao, Y. W., Bastieri, D., Bi, X. J., Bi, Y. J., Cai, J. T., Cao, Q., Cao, W. Y., Cao, Zhe, Chang, J., Chang, J. F., Chen, A. M., Chen, E. S., Chen, Liang, Chen, Lin, Chen, Long, Chen, M. J., Chen, M. L., Chen, Q. H., Chen, S. H., Chen, S. Z., Chen, T. L., Chen, Y., Cheng, N., Cheng, Y. D., Cui, M. Y., Cui, S. W., Cui, X. H., Cui, Y. D., Dai, B. Z., Dai, H. L., Dai, Z. G., Danzengluobu, della Volpe, D., Dong, X. Q., Duan, K. K., Fan, J. H., Fan, Y. Z., Fang, J., Fang, K., Feng, C. F., Feng, L., Feng, S. H., Feng, X. T., Feng, Y. L., Gabici, S., Gao, B., Gao, C. D., Gao, L. Q., Gao, Q., Gao, W., Gao, W. K., Ge, M. M., Geng, L. S., Giacinti, G., Gong, G. H., Gou, Q. B., Gu, M. H., Guo, F. L., Guo, X. L., Guo, Y. Q., Guo, Y. Y., Han, Y. A., He, H. H., He, H. N., He, J. Y., He, X. B., He, Y., Heller, M., Hor, Y. K., Hou, B. W., Hou, C., Hou, X., Hu, H. B., Hu, Q., Hu, S. C., Huang, D. H., Huang, T. Q., Huang, W. J., Huang, X. T., Huang, X. Y., Huang, Y., Huang, Z. C., Ji, X. L., Jia, H. Y., Jia, K., Jiang, K., Jiang, X. W., Jiang, Z. J., Jin, M., Kang, M. M., Ke, T., Kuleshov, D., Kurinov, K., Li, B. B., Li, Cheng, Li, Cong, Li, D., Li, F., Li, H. B., Li, H. C., Li, H. Y., Li, J., Li, Jian, Li, Jie, Li, K., Li, W. L., Li, X. R., Li, Xin, Li, Y. Z., Li, Zhe, Li, Zhuo, Liang, E. W., Liang, Y. F., Lin, S. J., Liu, B., Liu, C., Liu, D., Liu, H., Liu, H. D., Liu, J., Liu, J. L., Liu, J. Y., Liu, M. Y., Liu, R. Y., Liu, S. M., Liu, W., Liu, Y., Liu, Y. N., Lu, R., Luo, Q., Lv, H. K., Ma, B. Q., Ma, L. L., Ma, X. H., Mao, J. R., Min, Z., Mitthumsiri, W., Mu, H. J., Nan, Y. C., Neronov, A., Ou, Z. W., Pang, B. Y., Pattarakijwanich, P., Pei, Z. Y., Qi, M. Y., Qi, Y. Q., Qiao, B. Q., Qin, J. J., Ruffolo, D., Saiz, A., Semikoz, D., Shao, C. Y., Shao, L., Shchegolev, O., Sheng, X. D., Shu, F. W., Song, H. C., Stenkin, Yu. V., Stepanov, V., Su, Y., Sun, Q. N., Sun, X. N., Sun, Z. B., Tam, P. H. T., Tang, Q. W., Tang, Z. B., Tian, W. W., Wang, C., Wang, C. B., Wang, G. W., Wang, H. G., Wang, H. H., Wang, J. C., Wang, K., Wang, L. P., Wang, L. Y., Wang, P. H., Wang, R., Wang, W., Wang, X. G., Wang, X. Y., Wang, Y., Wang, Y. D., Wang, Y. J., Wang, Z. H., Wang, Z. X., Wang, Zhen, Wang, Zheng, Wei, D. M., Wei, J. J., Wei, Y. J., Wen, T., Wu, C. Y., Wu, H. R., Wu, S., Wu, X. F., Wu, Y. S., Xi, S. Q., Xia, J., Xia, J. J., Xiang, G. M., Xiao, D. X., Xiao, G., Xin, G. G., Xin, Y. L., Xing, Y., Xiong, Z., Xu, D. L., Xu, R. F., Xu, R. X., Xu, W. L., Xue, L., Yan, D. H., Yan, J. Z., Yan, T., Yang, C. W., Yang, F., Yang, F. F., Yang, H. W., Yang, J. Y., Yang, L. L., Yang, M. J., Yang, R. Z., Yang, S. B., Yao, Y. H., Yao, Z. G., Ye, Y. M., Yin, L. Q., Yin, N., You, X. H., You, Z. Y., Yu, Y. H., Yuan, Q., Yue, H., Zeng, H. D., Zeng, T. X., Zeng, W., Zha, M., Zhang, B. B., Zhang, F., Zhang, H. M., Zhang, H. Y., Zhang, J. L., Zhang, L. X., Zhang, Li, Zhang, P. F., Zhang, P. P., Zhang, R., Zhang, S. B., Zhang, S. R., Zhang, S. S., Zhang, X., Zhang, X. P., Zhang, Y. F., Zhang, Yi, Zhang, Yong, Zhao, B., Zhao, J., Zhao, L., Zhao, L. Z., Zhao, S. P., Zheng, F., Zhou, B., Zhou, H., Zhou, J. N., Zhou, M., Zhou, P., Zhou, R., Zhou, X. X., Zhu, C. G., Zhu, F. R., Zhu, H., Zhu, K. J., and Zuo, X.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The diffuse Galactic $\gamma$-ray emission, mainly produced via interactions between cosmic rays and the interstellar medium and/or radiation field, is a very important probe of the distribution, propagation, and interaction of cosmic rays in the Milky Way. In this work we report the measurements of diffuse $\gamma$-rays from the Galactic plane between 10 TeV and 1 PeV energies, with the square kilometer array of the Large High Altitude Air Shower Observatory (LHAASO). Diffuse emissions from the inner ($15^{\circ}10$~TeV). The energy spectrum in the inner Galaxy regions can be described by a power-law function with an index of $-2.99\pm0.04$, which is different from the curved spectrum as expected from hadronic interactions between locally measured cosmic rays and the line-of-sight integrated gas content. Furthermore, the measured flux is higher by a factor of $\sim3$ than the prediction. A similar spectrum with an index of $-2.99\pm0.07$ is found in the outer Galaxy region, and the absolute flux for $10\lesssim E\lesssim60$ TeV is again higher than the prediction for hadronic cosmic ray interactions. The latitude distributions of the diffuse emission are consistent with the gas distribution, while the longitude distributions show clear deviation from the gas distribution. The LHAASO measurements imply that either additional emission sources exist or cosmic ray intensities have spatial variations., Comment: 12 pages, 8 figures, 5 tables; accepted for publication in Physical Review Letters; source mask file provided as ancillary file
Published: 2023
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11. Flux Variations of Cosmic Ray Air Showers Detected by LHAASO-KM2A During a Thunderstorm on 10 June 2021

Author: LHAASO Collaboration, Aharonian, F., An, Q., Axikegu, Bai, L. X., Bai, Y. X., Bao, Y. W., Bastieri, D., Bi, X. J., Bi, Y. J., Cai, J. T., Cao, Zhe, Cao, Zhen, Chang, J., Chang, J. F., Chen, E. S., Chen, Liang, Chen, Long, Chen, M. J., Chen, M. L., Chen, S. H., Chen, S. Z., Chen, T. L., Chen, X. J., Chen, Y., Cheng, H. L., Cheng, N., Cheng, Y. D., Cui, S. W., Cui, X. H., Cui, Y. D., Dai, B. Z., Dai, H. L., Dai, Z. G., Danzengluobu, della Volpe, D., Duan, K. K., Fan, J. H., Fan, Y. Z., Fan, Z. X., Fang, J., Fang, K., Feng, C. F., Feng, L., Feng, S. H., Feng, X. T., Feng, Y. L., Gao, B., Gao, C. D., Gao, L. Q., Gao, Q., Gao, W., Gao, W. K., Ge, M. M., Geng, L. S., Gong, G. H., Gou, Q. B., Gu, M. H., Gu, F. L., Guo, J. G., Guo, X. L., Guo, Y. Q., Guo, Y. Y., Han, Y. A., He, H. H., He, H. N., He, S. L., He, X. B., He, Y., Heller, M., Hor, Y. K., Hou, C., Hou, X., Hu, H. B., Hu, Q., Hu, S., Hu, S. C., Hu, X. J., Huang, D. H., Huang, W. H., Huang, X. T., Huang, X. Y., Huang, Y., Huang, Z. C., Ji, X. L., Jia, H. Y., Jia, K., Jiang, K., Jiang, Z. J., Jin, M., Kang, M. M., Ke, T., Kuleshov, D., Li, B. B., Li, Cheng, Li, Cong, Li, F., Li, H. B., Li, H. C., Li, H. Y., Li, J., Li, Jian, Li, Jie, Li, K., Li, W. L., Li, X. R., Li, Xin, Li, Y. Z., Li, Zhe, Li, Zhuo, Liang, E. W., Liang, Y. F., Lin, S. J., Liu, B., Liu, C., Liu, D., Liu, H., Liu, H. D., Liu, J., Liu, J. L., Liu, J. S., Liu, J. Y., Liu, M. Y., Liu, R. Y., Liu, S. M., Liu, W., Liu, Y., Liu, Y. N., Long, W. J., Lu, R., Luo, Q., Lv, H. K., Ma, B. Q., Ma, L. L., Ma, X. H., Mao, J. R., Masood, A., Min, Z., Mitthumsiri, W., Nan, Y. C., Ou, Z. W., Pang, B. Y., Pattarakijwanich, P., Pei, Z. Y., Qi, M. Y., Qi, Y. Q., Qiao, B. Q., Qin, J. J., Ruffolo, D., Sáiz, A., Shao, C. Y., Shao, L., Shchegolev, O., Sheng, X. D., Shi, J. Y., Song, H. C., Stenkin, Yu. V., Stepanov, V., Su, Y., Sun, Q. N., Sun, X. N., Sun, Z. B., Tam, P. H. T., Tang, Z. B., Tian, W. W., Wang, B. D., Wang, C., Wang, H., Wang, H. G., Wang, J. C., Wang, J. S., Wang, L. P., Wang, L. Y., Wang, R., Wang, R. N., Wang, W., Wang, X. G., Wang, X. Y., Wang, Y., Wang, Y. D., Wang, Y. J., Wang, Y. P., Wang, Z. H. Wang. Z. X., Wang, Zhen, Wang, Zheng, Wei, D. M., Wei, J. J., Wei, Y. J., Wen, T., Wu, C. Y., Wu, H. R., Wu, S., Wu, X. F., W, Y. S., Xi, S. Q., Xia, J., Xia, J. J., Xiang, G. M., Xiao, D. X., Xiao, G., Xin, G. G., Xin, Y. L., Xing, Y., Xiong, Z., Xu, D. L., Xu, R. X., Xue, L., Yan, D. H., Yan, J. Z., Yang, C. W., Yang, F. F., Yang, H. W., Yang, J. Y., Yang, L. L., Yang, M. J., Yang, R. Z., Yang, S. B., Yao, Y. H., Yao, Z. G., Ye, Y. M., Yin, L. Q., Yin, N., You, X. H., You, Z. Y., Yu, Y. H., Yuan, Q., Yue, H., Zeng, H. D., Zeng, T. X., Zeng, W., Zeng, Z. K., Zha, M., Zhai, X. X., Zhang, B. B., Zhang, F., Zhang, H. M., Zhang, H. Y., Zhang, J. L., Zhang, L. X., Zhang, Li, Zhang, Lu, Zhang, P. F., Zhang, P. P., Zhang, R., Zhang, S. B., Zhang, S. R., Zhang, S. S., Zhang, X., Zhang, X. P., Zhang, Y. F., Zhang, Y. L., Zhang, Yi, Zhang, Yong, Zhao, B., Zhao, J., Zhao, L., Zhao, L. Z., Zhao, S. P., Zheng, F., Zheng, Y., Zhou, B., Zhou, H., Zhou, J. N., Zhou, P., Zhou, R., Zhou, X. X., Zhu, C. G., Zhu, F. R., Zhu, H., Zhu, K. J., and Zuo, X.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, High Energy Physics - Experiment
Abstract: The Large High Altitude Air Shower Observatory (LHAASO) has three sub-arrays, KM2A, WCDA and WFCTA. The flux variations of cosmic ray air showers were studied by analyzing the KM2A data during the thunderstorm on 10 June 2021. The number of shower events that meet the trigger conditions increases significantly in atmospheric electric fields, with maximum fractional increase of 20%. The variations of trigger rates (increases or decreases) are found to be strongly dependent on the primary zenith angle. The flux of secondary particles increases significantly, following a similar trend with that of the shower events. To better understand the observed behavior, Monte Carlo simulations are performed with CORSIKA and G4KM2A (a code based on GEANT4). We find that the experimental data (in saturated negative fields) are in good agreement with simulations, assuming the presence of a uniform upward electric field of 700 V/cm with a thickness of 1500 m in the atmosphere above the observation level. Due to the acceleration/deceleration and deflection by the atmospheric electric field, the number of secondary particles with energy above the detector threshold is modified, resulting in the changes in shower detection rate., Comment: 18 pages, 11 figures
Published: 2022
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12. Peta-electron volt gamma-ray emission from the Crab Nebula

Author: The LHAASO Collaboration, Cao, Zhen, Aharonian, F., An, Q., Axikegu, Bai, L. X., Bai, Y. X., Bao, Y. W., Bastieri, D., Bi, X. J., Bi, Y. J., Cai, H., Cai, J. T., Cao, Zhe, Chang, J., Chang, J. F., Chen, B. M., Chen, E. S., Chen, J., Chen, Liang, Chen, Long, Chen, M. J., Chen, M. L., Chen, Q. H., Chen, S. H., Chen, S. Z., Chen, T. L., Chen, X. L., Chen, Y., Cheng, N., Cheng, Y. D., Cui, S. W., Cui, X. H., Cui, Y. D., Piazzoli, B. D'Ettorre, Dai, B. Z., Dai, H. L., Dai, Z. G., Danzengluobu, della Volpe, D., Dong, X. J., Duan, K. K., Fan, J. H., Fan, Y. Z., Fan, Z. X., Fang, J., Fang, K., Feng, C. F., Feng, L., Feng, S. H., Feng, Y. L., Gao, B., Gao, C. D., Gao, L. Q., Gao, Q., Gao, W., Ge, M. M., Geng, L. S., Gong, G. H., Gou, Q. B., Gu, M. H., Guo, F. L., Guo, J. G., Guo, X. L., Guo, Y. Q., Guo, Y. Y., Han, Y. A., He, H. H., He, H. N., He, J. C., He, S. L., He, X. B., He, Y., Heller, M., Hor, Y. K., Hou, C., Hou, X., Hu, H. B., Hu, S., Hu, S. C., Hu, X. J., Huang, D. H., Huang, Q. L., Huang, W. H., Huang, X. T., Huang, X. Y., Huang, Z. C., Ji, F., Ji, X. L., Jia, H. Y., Jiang, K., Jiang, Z. J., Jin, C., Ke, T., Kuleshov, D., Levochkin, K., Li, B. B., Li, Cheng, Li, Cong, Li, F., Li, H. B., Li, H. C., Li, H. Y., Li, Jie, Li, Jian, Li, K., Li, W. L., Li, X. R., Li, Xin, Li, Y., Li, Y. Z., Li, Zhe, Li, Zhuo, Liang, E. W., Liang, Y. F., Lin, S. J., Liu, B., Liu, C., Liu, D., Liu, H., Liu, H. D., Liu, J., Liu, J. L., Liu, J. S., Liu, J. Y., Liu, M. Y., Liu, R. Y., Liu, S. M., Liu, W., Liu, Y., Liu, Y. N., Liu, Z. X., Long, W. J., Lu, R., Lv, H. K., Ma, B. Q., Ma, L. L., Ma, X. H., Mao, J. R., Masood, A., Min, Z., Mitthumsiri, W., Montaruli, T., Nan, Y. C., Pang, B. Y., Pattarakijwanich, P., Pei, Z. Y., Qi, M. Y., Qi, Y. Q., Qiao, B. Q., Qin, J. J., Ruffolo, D., Rulev, V., Sáiz, A., Shao, L., Shchegolev, O., Sheng, X. D., Shi, J. Y., Song, H. C., Stenkin, Yu. V., Stepanov, V., Su, Y., Sun, Q. N., Sun, X. N., Sun, Z. B., Tam, P. H. T., Tang, Z. B., Tian, W. W., Wang, B. D., Wang, C., Wang, H., Wang, H. G., Wang, J. C., Wang, J. S., Wang, L. P., Wang, L. Y., Wang, R. N., Wang, Wei, Wang, X. G., Wang, X. J., Wang, X. Y., Wang, Y., Wang, Y. D., Wang, Y. J., Wang, Y. P., Wang, Z. H., Wang, Z. X., Wang, Zhen, Wang, Zheng, Wei, D. M., Wei, J. J., Wei, Y. J., Wen, T., Wu, C. Y., Wu, H. R., Wu, S., Wu, W. X., Wu, X. F., Xi, S. Q., Xia, J., Xia, J. J., Xiang, G. M., Xiao, D. X., Xiao, G., Xiao, H. B., Xin, G. G., Xin, Y. L., Xing, Y., Xu, D. L., Xu, R. X., Xue, L., Yan, D. H., Yan, J. Z., Yang, C. W., Yang, F. F., Yang, J. Y., Yang, L. L., Yang, M. J., Yang, R. Z., Yang, S. B., Yao, Y. H., Yao, Z. G., Ye, Y. M., Yin, L. Q., Yin, N., You, X. H., You, Z. Y., Yu, Y. H., Yuan, Q., Zeng, H. D., Zeng, T. X., Zeng, W., Zeng, Z. K., Zha, M., Zhai, X. X., Zhang, B. B., Zhang, H. M., Zhang, H. Y., Zhang, J. L., Zhang, J. W., Zhang, L. X., Zhang, Li, Zhang, Lu, Zhang, P. F., Zhang, P. P., Zhang, R., Zhang, S. R., Zhang, S. S., Zhang, X., Zhang, X. P., Zhang, Y. F., Zhang, Y. L., Zhang, Yi, Zhang, Yong, Zhao, B., Zhao, J., Zhao, L., Zhao, L. Z., Zhao, S. P., Zheng, F., Zheng, Y., Zhou, B., Zhou, H., Zhou, J. N., Zhou, P., Zhou, R., Zhou, X. X., Zhu, C. G., Zhu, F. R., Zhu, H., Zhu, K. J., and Zuo, X.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The Crab pulsar and the surrounding nebula powered by the pulsar's rotational energy through the formation and termination of a relativistic electron-positron wind is a bright source of gamma-rays carrying crucial information about this complex conglomerate. We report the detection of $\gamma$-rays with a spectrum showing gradual steepening over three energy decades, from $5\times 10^{-4}$ to $1.1$ petaelectronvolt (PeV). The ultra-high-energy photons exhibit the presence of a PeV electron accelerator (a pevatron) with an acceleration rate exceeding 15% of the absolute theoretical limit. Assuming that unpulsed $\gamma$-rays are produced at the termination of the pulsar's wind, we constrain the pevatron's size, between $0.025$ and $0.1$ pc, and the magnetic field $\approx 110 \mu$G. The production rate of PeV electrons, $2.5 \times 10^{36}$ erg $\rm s^{-1}$, constitutes 0.5% of the pulsar's spin-down luminosity, although we do not exclude a non-negligible contribution of PeV protons to the production of the highest energy $\gamma$-rays., Comment: 43 pages, 13 figures, 2 tables; Published in Science
Published: 2021
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13. Calibration of the Air Shower Energy Scale of the Water and Air Cherenkov Techniques in the LHAASO experiment

Author: Aharonian, F., An, Q., Axikegu, Bai, L. X., Bai, Y. X., Bao, Y. W., Bastieri, D., Bi, X. J., Bi, Y. J., Cai, H., Cai, J. T., Cao, Z. Cao Z., Chang, J., Chang, J. F., Chang, X. C., Chen, B. M., Chen, J., Chen, L., Chen, M. J., Chen, M. L., Chen, Q. H., Chen, S. H., Chen, S. Z., Chen, T. L., Chen, X. L., Chen, Y., Cheng, N., Cheng, Y. D., Cui, S. W., Cui, X. H., Cui, Y. D., Dai, B. Z., Dai, H. L., Dai, Z. G., Danzengluobu, della Volpe, D., Piazzoli, B. DEttorre, Dong, X. J., Fan, J. H., Fan, Y. Z., Fan, Z. X., Fang, J., Fang, K., Feng, C. F., Feng, L., Feng, S. H., Feng, Y. L., Gao, B., Gao, C. D., Gao, Q., Gao, W., Ge, M. M., Geng, L. S., Gong, G. H., Gou, Q. B., Gu, M. H., Guo, J. G., Guo, X. L., Guo, Y. Q., Guo, Y. Y., Han, Y. A., He, H. H., He, H. N., He, J. C., He, S. L., He, X. B., He, Y., Heller, M., Hor, Y. K., Hou, C., Hou, X., Hu, H. B., Hu, S., Hu, S. C., Hu, X. J., Huang, D. H., Huang, Q. L., Huang, W. H., Huang, X. T., Huang, Z. C., Ji, F., Ji, X. L., Jia, H. Y., Jiang, K., Jiang, Z. J., Jin, C., Kuleshov, D., Levochkin, K., Li, B. B., Li, C., Li, F., Li, H. B., Li, H. C., Li, H. Y., Li, J., Li, K., Li, W. L., Li, X., Li, X. R., Li, Y., Li, Y. Z., Li, Z., Liang, E. W., Liang, Y. F., Lin, S. J., Liu, B., Liu, C., Liu, D., Liu, H., Liu, H. D., Liu, J., Liu, J. L., Liu, J. S., Liu, J. Y., Liu, M. Y., Liu, R. Y., Liu, S. M., Liu, W., Liu, Y. N., Liu, Z. X., Long, W. J., Lu, R., Lv, H. K., Ma, B. Q., Ma, L. L., Ma, X. H., Mao, J. R., Masood, A., Mitthumsiri, W., Montaruli, T., Nan, Y. C., Pang, B. Y., Pattarakijwanich, P., Pei, Z. Y., Qi, M. Y., Ruffolo, D., Rulev, V., Saiz, A., Shao, L., Shchegolev, O., Sheng, X. D., Shi, J. R., Song, H. C., Stenkin, Yu. V., Stepanov, V., Sun, Q. N., Sun, X. N., Sun, Z. B., Tam, P. H. T., Tang, Z. B., Tian, W. W., Wang, B. D., Wang, C., Wang, H., Wang, H. G., Wang, J. C., Wang, J. S., Wang, L. P., Wang, L. Y., Wang, R. N., Wang, W., Wang, X. G., Wang, X. J., Wang, X. Y., Wang, Y. D., Wang, Y. J., Wang, Y. P., Wang, Z., Wang, Z. H., Wang, Z. X., Wei, D. M., Wei, J. J., Wei, Y. J., Wen, T., Wu, C. Y., Wu, H. R., Wu, S., Wu, X., Wu, X. F., Xi, S. Q., Xia, J., Xia, J. J., Xiang, G. M., Xiao, G., Xiao, H. B., Xin, G. G., Xin, Y. L., Xing, Y., Xu, D. L., Xu, R. X., Xue, L., Yan, D. H., Yang, C. W., Yang, F. F., Yang, J. Y., Yang, L. L., Yang, M. J., Yang, R. Z., Yang, S. B., Yao, Y. H., Yao, Z. G., Ye, Y. M., Yin, L. Q., Yin, N., You, X. H., You, Z. Y., Yu, Y. H., Yuan, Q., Zeng, H. D., Zeng, T. X., Zeng, W., Zeng, Z. K., Zha, M., Zhai, X. X., Zhang, B. B., Zhang, H. M., Zhang, H. Y., Zhang, J. L., Zhang, J. W., Zhang, L., Zhang, L. X., Zhang, P. F., Zhang, P. P., Zhang, R., Zhang, S. R., Zhang, S. S., Zhang, X., Zhang, X. P., Zhang, Y., Zhang, Y. F., Zhang, Y. L., Zhao, B., Zhao, J., Zhao, L., Zhao, L. Z., Zhao, S. P., Zheng, F., Zheng, Y., Zhou, B., Zhou, H., Zhou, J. N., Zhou, P., Zhou, R., Zhou, X. X., Zhu, C. G., Zhu, F. R., Zhu, H., Zhu, K. J., and Zuo, X.
Subjects: Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract: The Wide Field-of-View Cherenkov Telescope Array (WFCTA) and the Water Cherenkov Detector Arrays (WCDA) of LHAASO are designed to work in combination for measuring the energy spectra of various cosmic ray species over a very wide energy range from a few TeV to 10 PeV. The energy calibration of WCDA can be achieved with a proven technique of measuring the westward shift of the Moon shadow of galactic cosmic rays due to the geomagnetic field. This deflection angle $\Delta$ is inversely proportional to the energy of the cosmic rays. The precise measurements of the shifts by WCDA allows us to calibrate its energy scale for energies as high as 35 TeV. The energy scale measured by WCDA can be used to cross calibrate the energy reconstructed by WFCTA, which spans the whole energy range up to 10 PeV. In this work, we will demonstrate the feasibility of the method using the data collected from April 2019 to January 2020 by the WFCTA array and WCDA-1 detector, the first of the three water Cherenkov ponds, already commissioned at LHAASO site.
Published: 2021
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14. The observation of the Crab Nebula with LHAASO-KM2A for the performance study

Author: Aharonian, F., An, Q., Axikegu, Bai, L. X., Bai, Y. X., Bao, Y. W., Bastieri, D., Bi, X. J., Bi, Y. J., Cai, H., Cai, J. T., Cao, Z., Chang, J., Chang, J. F., Chang, X. C., Chen, B. M., Chen, J., Chen, L., Chen, M. J., Chen, M. L., Chen, Q. H., Chen, S. H., Chen, S. Z., Chen, T. L., Chen, X. L., Chen, Y., Cheng, N., Cheng, Y. D., Cui, S. W., Cui, X. H., Cui, Y. D., Dai, B. Z., Dai, H. L., Dai, Z. G., Danzengluobu, della Volpe, D., Piazzoli, B. D'Ettorre, Dong, X. J., Fan, J. H., Fan, Y. Z., Fan, Z. X., Fang, J., Fang, K., Feng, C. F., Feng, L., Feng, S. H., Feng, Y. L., Gao, B., Gao, C. D., Gao, Q., Gao, W., Ge, M. M., Geng, L. S., Gong, G. H., Gou, Q. B., Gu, M. H., Guo, J. G., Guo, X. L., Guo, Y. Q., Guo, Y. Y., Han, Y. A., He, H. H., He, H. N., He, J. C., He, S. L., He, X. B., He, Y., Heller, M., Hor, Y. K., Hou, C., Hou, X., Hu, H. B., Hu, S., Hu, S. C., Hu, X. J., Huang, D. H., Huang, Q. L., Huang, W. H., Huang, X. T., Huang, Z. C., Ji, F., Ji, X. L., Jia, H. Y., Jiang, K., Jiang, Z. J., Jin, C., Kuleshov, D., Levochkin, K., Li, B. B., Li, C., Li, F., Li, H. B., Li, H. C., Li, H. Y., Li, J., Li, K., Li, W. L., Li, X., Li, X. R., Li, Y., Li, Y. Z., Li, Z., Liang, E. W., Liang, Y. F., Lin, S. J., Liu, B., Liu, C., Liu, D., Liu, H., Liu, H. D., Liu, J., Liu, J. L., Liu, J. S., Liu, J. Y., Liu, M. Y., Liu, R. Y., Liu, S. M., Liu, W., Liu, Y. N., Liu, Z. X., Long, W. J., Lu, R., Lv, H. K., Ma, B. Q., Ma, L. L., Ma, X. H., Mao, J. R., Masood, A., Mitthumsiri, W., Montaruli, T., Nan, Y. C., Pang, B. Y., Pattarakijwanich, P., Pei, Z. Y., Qi, M. Y., Ruffolo, D., Rulev, V., Sáiz, A., Shao, L., Shchegolev, O., Sheng, X. D., Shi, J. R., Song, H. C., Stenkin, Yu. V., Stepanov, V., Sun, Q. N., Sun, X. N., Sun, Z. B., Tam, P. H. T., Tang, Z. B., Tian, W. W., Wang, B. D., Wang, C., Wang, H., Wang, H. G., Wang, J. C., Wang, J. S., Wang, L. P., Wang, L. Y., Wang, R. N., Wang, W., Wang, X. G., Wang, X. J., Wang, X. Y., Wang, Y. D., Wang, Y. J., Wang, Y. P., Wang, Z., Wang, Z. H., Wang, Z. X., Wei, D. M., Wei, J. J., Wei, Y. J., Wen, T., Wu, C. Y., Wu, H. R., Wu, S., Wu, W. X., Wu, X. F., Xi, S. Q., Xia, J., Xia, J. J., Xiang, G. M., Xiao, G., Xiao, H. B., Xin, G. G., Xin, Y. L., Xing, Y., Xu, D. L., Xu, R. X., Xue, L., Yan, D. H., Yang, C. W., Yang, F. F., Yang, J. Y., Yang, L. L., Yang, M. J., Yang, R. Z., Yang, S. B., Yao, Y. H., Yao, Z. G., Ye, Y. M., Yin, L. Q., Yin, N., You, X. H., You, Z. Y., Yu, Y. H., Yuan, Q., Zeng, H. D., Zeng, T. X., Zeng, W., Zeng, Z. K., Zha, M., Zhai, X. X., Zhang, B. B., Zhang, H. M., Zhang, H. Y., Zhang, J. L., Zhang, J. W., Zhang, L., Zhang, L. X., Zhang, P. F., Zhang, P. P., Zhang, R., Zhang, S. R., Zhang, S. S., Zhang, X., Zhang, X. P., Zhang, Y., Zhang, Y. F., Zhang, Y. L., Zhao, B., Zhao, J., Zhao, L., Zhao, L. Z., Zhao, S. P., Zheng, F., Zheng, Y., Zhou, B., Zhou, H., Zhou, J. N., Zhou, P., Zhou, R., Zhou, X. X., Zhu, C. G., Zhu, F. R., Zhu, H., Zhu, K. J., and Zuo, X.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: As a sub-array of the Large High Altitude Air Shower Observatory (LHAASO), KM2A is mainly designed to cover a large fraction of the northern sky to hunt for gamma-ray sources at energies above 10 TeV. Even though the detector construction is still underway, a half of the KM2A array has been operating stably since the end of 2019. In this paper, we present the pipeline of KM2A data analysis and the first observation on the Crab Nebula, a standard candle in very high energy gamma-ray astronomy. We detect gamma-ray signals from the Crab Nebula in both energy ranges of 10$-$100 TeV and $>$100 TeV with high significance, by analyzing the KM2A data of 136 live days between December 2019 and May 2020. With the observations, we test the detector performance including angular resolution, pointing accuracy and cosmic ray background rejection power. The energy spectrum of the Crab Nebula in the energy range 10-250 TeV fits well with a single power-law function dN/dE =(1.13$\pm$0.05$_{stat}$$\pm$0.08$_{sys}$)$\times$10$^{-14}$$\cdot$(E/20TeV)$^{-3.09\pm0.06_{stat}\pm0.02_{sys}}$ cm$^{-2}$ s$^{-1}$ TeV$^{-1}$. It is consistent with previous measurements by other experiments. This opens a new window of gamma-ray astronomy above 0.1 PeV through which ultrahigh-energy gamma-ray new phenomena, such as cosmic PeVatrons, might be discovered., Comment: 13 pages, 15 figures,submitted to CPC
Published: 2020
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15. SN 2018hti: a nearby superluminous supernova discovered in a metal-poor galaxy

Author: Lin, W. L., Wang, X. F., Li, W. X., Zhang, J. J., Mo, J., Sai, H. N., Zhang, X. H., Filippenko, A. V., Zheng, W. K., Brink, T. G., Baron, E., DerKacy, J. M., Ehgamberdiev, S. A., Mirzaqulov, D., Li, X., Zhang, J. C., Yan, S. Y., Xi, G. B., Hsiao, Y., Zhang, T. M., Wang, L. J., Liu, L. D., Xiang, D. F., Wu, C. Y., Rui, L. M., and Chen, Z. H.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: SN 2018hti is a Type I superluminous supernova (SLSN~I) with an absolute $g$-band magnitude of $-22.2$ at maximum brightness, discovered in a metal-poor galaxy at a redshift of 0.0612. We present extensive photometric and spectroscopic observations of this supernova, covering the phases from $\sim -35$ days to more than +340 days from the $r$-band maximum. Combining our $BVgri$-band photometry with {\it Swift} UVOT optical/ultraviolet photometry, we calculated the peak luminosity as $\sim 3.5\times10^{44}$ erg s$^{-1}$. Modeling the observed light curve reveals that the luminosity evolution of SN 2018hti can be produced by an ejecta mass of 5.8 $M_\odot$ and a magnetar with a magnetic field of $B=1.8\times10^{13}$~G having an initial spin period of $P_0=1.8$ ms. Based on such a magnetar-powered scenario and a larger sample, a correlation between the spin of the magnetar and the kinetic energy of the ejecta can be inferred for most SLSNe~I, suggesting a self-consistent scenario. Like for other SLSNe~I, the host galaxy of SN 2018hti is found to be relatively faint ($M_{g} = -17.75$ mag) and of low metallicity ($Z=0.3~Z_\odot$), with a star-formation rate of 0.3 $M_\odot$ yr$^{-1}$. According to simulation results of single-star evolution, SN 2018hti could originate from a massive, metal-poor star with a zero-age main sequence (ZAMS) mass of 25--40 $M_\odot$, or from a less massive rotating star with $M_\mathrm{ZAMS} \approx 16$--25 $M_\odot$. For the case of a binary system, its progenitor could also be a star with $M_\mathrm{ZAMS} \gtrsim 25$ $M_\odot$., Comment: 26 pages, 12 figures, 7 tables, published in MNRAS
Published: 2020
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16. Search for gamma-ray emission from the Sun during solar minimum with the ARGO-YBJ experiment

Author: Bartoli, B., Bernardini, P., Bi, X. J., Cao, Z., Catalanotti, S., Chen, S. Z., Chen, T. L., Cui, S. W., Dai, B. Z., D'Amone, A., Danzengluobu, De Mitri, I., Piazzoli, B. D'Ettorre, Di Girolamo, T., Di Sciascio, G., Feng, C. F., Feng, Zhaoyang, Feng, Zhenyong, Gao, W., Gou, Q. B., Guo, Y. Q., He, H. H., Hu, Haibing, Hu, Hongbo, Iacovacci, M., Iuppa, R., Jia, H. Y., Labaciren, Li, H. J., Li, Z., Liu, C., Liu, J., Liu, M. Y., Lu, H., Ma, L. L., Ma, X. ., Mancarella, G., Mari, S. M., Marsella, G., Mastroianni, S., Montini, P., Ning, C. C., Perrone, L., Pistilli, P., Salvini, P., Santonico, R., Shen, P. R., Sheng, X. D., Shi, F., Surdo, A., Tan, Y. H., Vallania, P., Vernetto, S., Vigorito, C., Wang, H., Wu, C. Y., Wu, H. R., Xue, L., Yang, Q. Y., Yang, X. C., Yao, Z. G., Yuan, A. F., Zha, M., Zhang, H. M., Zhang, L., Zhang, X. Y., Zhang, Y., Zhao, J., Zhaxiciren, Zhaxisangzhu, Zhou, X. X., Zhu, F. R., and Zhu, Q. Q.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The hadronic interaction of cosmic rays with solar atmosphere can produce high energy gamma rays. The gamma-ray luminosity is correlated both with the flux of primary cosmic rays and the intensity of the solar magnetic field. The gamma rays below 200 GeV have been observed by $Fermi$ without any evident energy cutoff. The bright gamma-ray flux above 100 GeV has been detected only during solar minimum. The only available data in TeV range come from the HAWC observations, however outside the solar minimum. The ARGO-YBJ dataset has been used to search for sub-TeV/TeV gamma rays from the Sun during the solar minimum from 2008 to 2010, the same time period covered by the Fermi data. A suitable model containing the Sun shadow, solar disk emission and inverse-Compton emission has been developed, and the chi-square minimization method was used to quantitatively estimate the disk gamma-ray signal. The result shows that no significant gamma-ray signal is detected and upper limits to the gamma-ray flux at 0.3$-$7 TeV are set at 95\% confidence level. In the low energy range these limits are consistent with the extrapolation of the Fermi-LAT measurements taken during solar minimum and are compatible with a softening of the gamma-ray spectrum below 1 TeV. They provide also an experimental upper bound to any solar disk emission at TeV energies. Models of dark matter annihilation via long-lived mediators predicting gamma-ray fluxes > $10^{-7}$ GeV $cm^{-2}$ $s^{-1}$ below 1 TeV are ruled out by the ARGO-YBJ limits.
Published: 2019
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17. Galactic Cosmic-Ray Anisotropy in the Northern hemisphere from the ARGO-YBJ Experiment during 2008-2012

Author: Bartoli, B., Bernardini, P., Bi, X. J., Cao, Z., Catalanotti, S., Chen, S. Z., Chen, T. L., Cui, S. W., Dai, B. Z., D'Amone, A., Danzengluobu, De Mitri, I., Piazzoli, B. D'Ettorre, Di Girolamo, T., Di Sciascio, G., Feng, C. F., Feng, Z. Y., Gao, W., Gou, Q. B., Guo, Y. Q., He, H. H., Hu, Haibing, Hu, Hongbo, Iacovacci, M., Iuppa, R., Jia, H. Y., Labaciren, Li, H. J., Liu, C., Liu, J., Liu, M. Y., Lu, H., Ma, L. L., Ma, X. H., Mancarella, G., Mari, S. M., Marsella, G., Mastroianni, S., Montini, P., Ning, C. C., Perrone, L., Pistilli, P., Ruffolo, D., Salvini, P., Santonico, R., Shen, P. R., Sheng, X. D., Shi, F., Surdo, A., Tan, Y. H., Vallania, P., Vernetto, S., Vigorito, C., Wang, H., Wu, C. Y., Wu, H. R., Xue, L., Yang, Q. Y., Yang, X. C., Yao, Z. G., Yuan, A. F., Zha, M., Zhang, H. M., Zhang, L., Zhang, X. Y., Zhang, Y., Zhao, J., Zhaxiciren, Zhaxisangzhu, Zhou, X. X., Zhu, F. R., and Zhu, Q. Q.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: This paper reports on the observation of the sidereal large-scale anisotropy of cosmic rays using data collected by the ARGO-YBJ experiment over 5 years (2008$-$2012). This analysis extends previous work limited to the period from 2008 January to 2009 December,near the minimum of solar activity between cycles 23 and 24.With the new data sample the period of solar cycle 24 from near minimum to maximum is investigated. A new method is used to improve the energy reconstruction, allowing us to cover a much wider energy range, from 4 to 520 TeV. Below 100 TeV, the anisotropy is dominated by two wide regions, the so-called "tail-in" and "loss-cone" features. At higher energies, a dramatic change of the morphology is confirmed. The yearly time dependence of the anisotropy is investigated. Finally, no noticeable variation of cosmic-ray anisotropy with solar activity is observed for a median energy of 7 TeV.
Published: 2018
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18. Observation of the thunderstorm-related ground cosmic ray flux variations by ARGO-YBJ

Author: Bartoli, B., Bernardini, P., Bi, X. J., Cao, Z., Catalanotti, S., Chen, S. Z., Chen, T. L., Cui, S. W., Dai, B. Z., Amone, A. D, Luobu, Danzeng, De Mitri, I., Piazzoli, B. D Ettorre, Di Girolamo, T., Di Sciascio, G., Feng, C. F., Feng, Zhaoyang, Feng, Zhenyong, Gao, W., Gou, Q. B., Guo, Y. Q., He, H. H., Hu, Haibing, Hu, Hongbo, Iacovacci, M., Iuppa, R., Jia, H. Y., Ren, Labaci, Li, H. J., Liu, C., Liu, J., Liu, M. Y., Lu, H., Ma, L. L., Ma, X. H., Mancarella, G., Mari, S. M., Marsella, G., Mastroianni, S., Montini, P., Ning, C. C., Perrone, L., Pistilli, P., Salvini, P., Santonico, R., Shen, P. R., Sheng, X. D., Shi, F., Surdo, A., Tan, Y. H., Vallania, P., Vernetto, S., Vigorito, C., Wang, H., Wu, C. Y., Wu, H. R., Xue, L., Yang, Q. Y., Yang, X. C., Yao, Z. G., Yuan, A. F., Zha, M., Zhang, H. M., Zhang, L., Zhang, X. Y., Zhang, Y., Zhao, J., Ren, Zhaxici, Zhu, Zhaxisang, Zhou, X. X., Zhu, F. R., Zhu, Q. Q., and Alessandro, F. D.
Subjects: Astrophysics - Earth and Planetary Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract: A correlation between the secondary cosmic ray flux and the near-earth electric field intensity, measured during thunderstorms, has been found by analyzing the data of the ARGO-YBJ experiment, a full coverage air shower array located at the Yangbajing Cosmic Ray Laboratory (4300 m a. s. l., Tibet, China). The counting rates of showers with different particle multiplicities, have been found to be strongly dependent upon the intensity and polarity of the electric field measured during the course of 15 thunderstorms. In negative electric fields (i.e. accelerating negative charges downwards), the counting rates increase with increasing electric field strength. In positive fields, the rates decrease with field intensity until a certain value of the field EFmin (whose value depends on the event multiplicity), above which the rates begin increasing. By using Monte Carlo simulations, we found that this peculiar behavior can be well described by the presence of an electric field in a layer of thickness of a few hundred meters in the atmosphere above the detector, which accelerates/decelerates the secondary shower particles of opposite charge, modifying the number of particles with energy exceeding the detector threshold. These results, for the first time, give a consistent explanation for the origin of the variation of the electron/positron flux observed for decades by high altitude cosmic ray detectors during thunderstorms., Comment: 17 pages, 11 figures. The paper has been accepted by PRD
Published: 2017
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19. EAS age determination from the study of the lateral distribution of charged particles near the shower axis with the ARGO-YBJ experiment

Author: Collaboration, ARGO-YBJ, Bartoli, B., Bernardini, P., Bi, X. J., Cao, Z., Catalanotti, S., Chen, S. Z., Chen, T. L., Cui, S. W., Dai, B. Z., D'Amone, A., Danzengluobu, De Mitri, I., Piazzoli, B. D'Ettorre, Di Girolamo, T., Di Sciascio, G., Feng, C. F., Feng, Zhaoyang, Feng, Zhenyong, Gou, Q. B., Guo, Y. Q., He, H. H., Hu, Haibing, Hu, Hongbo, Iacovacci, M., Iuppa, R., Jia, H. Y., Labaciren, Li, H. J., Liu, C., Liu, J., Liu, M. Y., Lu, H., Ma, L. L., Ma, X. H., Mancarella, G., Mari, S. M., Marsella, G., Mastroianni, S., Montini, P., Ning, C. C., Perrone, L., Pistilli, P., Salvini, P., Santonico, R., Shen, P. R., Sheng, X. D., Shi, F., Surdo, A., Tan, Y. H., Vallania, P., Vernetto, S., Vigorito, C., Wang, H., Wu, C. Y., Wu, H. R., Xue, L., Yang, Q. Y., Yang, X. C., Yao, Z. G., Yuan, A. F., Zha, M., Zhang, H. M., Zhang, L., Zhang, X. Y., Zhang, Y., Zhao, J., Zhaxiciren, Zhaxisangzhu, Zhou, X. X., Zhu, F. R., and Zhu, Q. Q.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, High Energy Physics - Experiment
Abstract: The ARGO-YBJ experiment, a full coverage extensive air shower (EAS) detector located at high altitude (4300 m a.s.l.) in Tibet, China, has smoothly taken data, with very high stability, since November 2007 to the beginning of 2013. The array consisted of a carpet of about 7000 m$^2$ Resistive Plate Chambers (RPCs) operated in streamer mode and equipped with both digital and analog readout, providing the measurement of particle densities up to few particles per cm$^2$. The unique detector features (full coverage, readout granularity, wide dynamic range, etc) and location (very high altitude) allowed a detailed study of the lateral density profile of charged particles at ground very close to the shower axis and its description by a proper lateral distribution function (LDF). In particular, the information collected in the first 10 m from the shower axis have been shown to provide a very effective tool for the determination of the shower development stage ("age") in the energy range 50 TeV - 10 PeV. The sensitivity of the age parameter to the mass composition of primary Cosmic Rays is also discussed.
Published: 2017
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20. Search for Gamma Ray Bursts with the ARGO-YBJ Detector in Shower Mode

Author: Bartoli, B., Bernardini, P., Bi, X. J., Cao, Z., Catalanotti, S., Chen, S. Z., Chen, T. L., Cui, S. W., Dai, B. Z., Amone, A. D, Luobu, Danzeng, De Mitri, I., Piazzoli, B. D Ettorre, Di Girolamo, T., Di Sciascio, G., Feng, C. F., Feng, Zhaoyang, Feng, Zhenyong, Gao, W., Gou, Q. B., Guo, Y. Q., He, H. H., Hu, Haibing, Hu, Hongbo, Iacovacci, M., Iuppa, R., Jia, H. Y., Ren, Labaci, Li, H. J., Liu, C., Liu, J., Liu, M. Y., Lu, H., Ma, L. L., Ma, X. H., Mancarella, G., Mari, S. M., Marsella, G., Mastroianni, S., Montini, P., Ning, C. C., Perrone, L., Pistilli, P., Salvini, P., Santonico, R., Shen, P. R., Sheng, X. D., Shi, F., Surdo, A., Tan, Y. H., Vallania, P., Vernetto, S., Vigorito, C., Wang, H., Wu, C. Y., Wu, H. R., Xue, L., Yang, Q. Y., Yang, X. C., Yao, Z. G., Yuan, A. F., Zha, M., Zhang, H. M., Zhang, L., Zhang, X. Y., Zhang, Y., Zhao, J., Ren, Zhaxici, Zhu, Zhaxisang, Zhou, X. X., Zhu, F. R., and Zhu, Q. Q.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, High Energy Physics - Phenomenology
Abstract: The ARGO-YBJ detector, located at the Yangbajing Cosmic Ray Laboratory (4300 m a. s. l., Tibet, China), was a full coverage air shower array dedicated to gamma ray astronomy and cosmic ray studies. The wide field of view (~ 2 sr) and high duty cycle (> 86%), made ARGO-YBJ suitable to search for short and unexpected gamma ray emissions like gamma ray bursts (GRBs). Between 2007 November 6 and 2013 February 7, 156 satellite-triggered GRBs (24 of them with known redshift) occurred within the ARGO-YBJ field of view. A search for possible emission associated to these GRBs has been made in the two energy ranges 10-100 GeV and 10-1000 GeV. No significant excess has been found in time coincidence with the satellite detections nor in a time window of one hour after the bursts. Taking into account the EBL absorption, upper limits to the energy fluence at 99% of confidence level have been evaluated,with values ranging from ~ 10-5 erg cm-2 to ~10-1 erg cm-2., Comment: 24pages and 12 figures
Published: 2017
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21. Detection of thermal neutrons with the PRISMA-YBJ array in Extensive Air Showers selected by the ARGO-YBJ experiment

Author: Bartoli, B., Bernardini, P., Bi, X. J., Cao, Z., Catalanotti, S., Chen, S. Z., Chen, T. L., Cui, S. W., Dai, B. Z., D'Amone, A., Danzengluobu, De Mitri, I., Piazzoli, B. D'Ettorre, Di Girolamo, T., Di Sciascio, G., Feng, C. F., Feng, Zhaoyang, Feng, Zhenyong, Gou, Q. B., Guo, Y. Q., He, H. H., Hu, Haibing, Hu, Hongbo, Iacovacci, M., Iuppa, R., Jia, H. Y., Labaciren, Li, H. J., Liu, C., Liu, J., Liu, M. Y., Lu, H., Ma, L. L., Ma, X. H., Mancarella, G., Mari, S. M., Marsella, G., Mastroianni, S., Montini, P., Ning, C. C., Perrone, L., Pistilli, P., Salvini, P., Santonico, R., Shen, P. R., Sheng, X. D., Shi, F., Surdo, A., Tan, Y. H., Vallania, P., Vernetto, S., Vigorito, C., Wang, H., Wu, C. Y., Wu, H. R., Xue, L., Yang, Q. Y., Yang, X. C., Yao, Z. G., Yuan, A. F., Zha, M., Zhang, H. M., Zhang, L., Zhang, X. Y., Zhang, Y., Zhao, J., Zhaxiciren, Zhaxisangzhu, Zhou, X. X., Zhu, F. R., Zhu, Q. Q., Stenkin, . Yu. V., Alekseenko, V. V., Aynutdinov, V., Cai, Z. Y., Guo, X. W., Liu, Y., Rulev, V., Shchegolev, O. B., Stepanov, V., Volchenko, V., and Zhang, H.
Subjects: Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Physics - Instrumentation and Detectors
Abstract: We report on a measurement of thermal neutrons, generated by the hadronic component of extensive air showers (EAS), by means of a small array of EN-detectors developed for the PRISMA project (PRImary Spectrum Measurement Array), novel devices based on a compound alloy of ZnS(Ag) and $^{6}$LiF. This array has been operated within the ARGO-YBJ experiment at the high altitude Cosmic Ray Observatory in Yangbajing (Tibet, 4300 m a.s.l.). Due to the tight correlation between the air shower hadrons and thermal neutrons, this technique can be envisaged as a simple way to estimate the number of high energy hadrons in EAS. Coincident events generated by primary cosmic rays of energies greater than 100 TeV have been selected and analyzed. The EN-detectors have been used to record simultaneously thermal neutrons and the air shower electromagnetic component. The density distributions of both components and the total number of thermal neutrons have been measured. The correlation of these data with the measurements carried out by ARGO-YBJ confirms the excellent performance of the EN-detector., Comment: 35 pages, 16 figures
Published: 2015
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22. 4.5 years multi-wavelength observations of Mrk 421 during the ARGO-YBJ and Fermi common operation time

Author: Bartoli, B., Bernardini, P., Bi, X. J., Cao, Z., Catalanotti, S., Chen, S. Z., Chen, T. L., Cui, S. W., Dai, B. Z., Damone, A., Danzengluobu, De Mitri, I., Piazzoli, B. D Ettorre, Di Girolamo, T., Di Sciascio, G., Feng, C. F., Feng, Zhaoyang, Feng, Zhenyong, Gou, Q. B., Guo, Y. Q., He, H. H., Hu, Haibing, Hu, Hongbo, Iacovacci, M., Iuppa, R., Jia, H. Y., Labaciren, Li, H. J., Liu, C., Liu, J., Liu, M. Y., Lu, H., Ma, L. L., Ma, X. H., Mancarella, G., Mari, S. M., Marsella, G., Mastroianni, S., Montini, P., Ning, C. C., Perrone, L., Pistilli, P., Salvini, P., Santonico, R., Shen, P. R., Sheng, X. D., Shi, F., Surdo, A., Tan, Y. H., Vallania, P., Vernetto, S., Vigorito, C., Wang, H., Wu, C. Y., Wu, H. R., Xue, L., Yang, Q. Y., Yang, X. C., Yao, Z. G., Yuan, A. F., Zha, M., Zhang, H. M., Zhang, L., Zhang, X. Y., Zhang, Y., Zhao, J., Zhaxiciren, Zhaxisangzhu, Zhou, X. X., Zhu, F. R., and Zhu, Q. Q.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We report on the extensive multi-wavelength observations of the blazar Markarian 421 (Mrk 421) covering radio to gamma-rays, during the 4.5 year period of ARGO-YBJ and Fermi common operation time, from August 2008 to February 2013. In particular, thanks to the ARGO-YBJ and Fermi data, the whole energy range from 100 MeV to 10 TeV is covered without any gap. In the observation period, Mrk 421 showed both low and high activity states at all wavebands. The correlations among flux variations in different wavebands were analyzed. Seven large flares, including five X-ray flares and two GeV gamma-ray flares with variable durations (3-58 days), and one X-ray outburst phase were identified and used to investigate the variation of the spectral energy distribution with respect to a relative quiescent phase. During the outburst phase and the seven flaring episodes, the peak energy in X-rays is observed to increase from sub-keV to few keV. The TeV gamma-ray flux increases up to 0.9-7.2 times the flux of the Crab Nebula. The behavior of GeV gamma-rays is found to vary depending on the flare, a feature that leads us to classify flares into three groups according to the GeV flux variation. Finally, the one-zone synchrotron self-Compton model was adopted to describe the emission spectra. Two out of three groups can be satisfactorily described using injected electrons with a power-law spectral index around 2.2, as expected from relativistic diffuse shock acceleration, whereas the remaining group requires a harder injected spectrum. The underlying physical mechanisms responsible for different groups may be related to the acceleration process or to the environment properties., Comment: 17 pages, 9 figures, 5 tables, Accepted for publication in ApJS
Published: 2015
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23. Study of the diffuse gamma-ray emission from the Galactic plane with ARGO-YBJ

Author: Bartoli, B., Bernardini, P., Bi, X. J., Branchini, P., Budano, A., Camarri, P., Cao, Z., Cardarelli, R., Catalanotti, S., Chen, S. Z., Chen, T. L., Creti, P., Cui, S. W., Dai, B. Z., D'Amone, A., Danzengluobu, De Mitri, I., Piazzoli, B. D'Ettorre, Di Girolamo, T., Di Sciascio, G., Feng, C. F., Feng, Zhaoyang, Feng, Zhenyong, Gou, Q. B., Guo, Y. Q., He, H. H., Hu, Haibing, Hu, Hongbo, Iacovacci, M., Iuppa, R., Jia, H. Y., Labaciren, Li, H. J., Liguori, G., Liu, C., Liu, J., Liu, M. Y., Lu, H., Ma, L. L., Ma, X. H., Mancarella, G., Mari, S. M., Marsella, G., Martello, D., Mastroianni, S., Montini, P., Ning, C. C., Panareo, M., Perrone, L., Pistilli, P., Ruggieri, F., Salvini, P., Santonico, R., Shen, P. R., Sheng, X. D., Shi, F., Surdo, A., Tan, Y. H., Vallania, P., Vernetto, S., Vigorito, C., Wang, H., Wu, C. Y., Wu, H. R., Xue, L., Yang, Q. Y., Yang, X. C., Yao, Z. G., Yuan, A. F., Zha, M., Zhang, H. M., Zhang, L., Zhang, X. Y., Zhang, Y., Zhao, J., Zhaxiciren, Zhaxisangzhu, Zhou, X. X., Zhu, F. R., Zhu, Q. Q., and Zizzi, G.
Subjects: Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, High Energy Physics - Phenomenology
Abstract: The events recorded by ARGO-YBJ in more than five years of data collection have been analyzed to determine the diffuse gamma-ray emission in the Galactic plane at Galactic longitudes 25{\deg} < l < 100{\deg} and Galactic latitudes . The energy range covered by this analysis, from ~350 GeV to ~2 TeV, allows the connection of the region explored by Fermi with the multi-TeV measurements carried out by Milagro. Our analysis has been focused on two selected regions of the Galactic plane, i.e., 40{\deg} < l < 100{\deg} and 65{\deg} < l < 85{\deg} (the Cygnus region), where Milagro observed an excess with respect to the predictions of current models. Great care has been taken in order to mask the most intense gamma-ray sources, including the TeV counterpart of the Cygnus cocoon recently identified by ARGO-YBJ, and to remove residual contributions. The ARGO-YBJ results do not show any excess at sub-TeV energies corresponding to the excess found by Milagro, and are consistent with the predictions of the Fermi model for the diffuse Galactic emission. From the measured energy distribution we derive spectral indices and the differential flux at 1 TeV of the diffuse gamma-ray emission in the sky regions investigated., Comment: 11 pages, 6 figures, published in APJ
Published: 2015
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24. The cosmic ray proton plus helium energy spectrum measured by the ARGO-YBJ experiment in the energy range 3-300 TeV

Author: Collaboration, The ARGO-YBJ, Bartoli, B., Bernardini, P., Bi, X. J., Cao, Z., Catalanotti, S., Chen, S. Z., Chen, T. L., Cui, S. W., Dai, B. Z., D'Amone, A., Danzengluobu, De Mitri, I., Piazzoli, B. D'Ettorre, Di Girolamo, T., Di Sciascio, G., Feng, C. F., Feng, Zhaoyang, Feng, Zhenyong, Gou, Q. B., Guo, Y. Q., He, H. H., Hu, Haibing, Hu, Hongbo, Iacovacci, M., Iuppa, R., Jia, H. Y., Labaciren, Li, H. J., Liu, C., Liu, J., Liu, M. Y., Lu, H., Ma, L. L., Ma, X. H., Mancarella, G., Mari, S. M., Marsella, G., Mastroianni, S., Montini, P., Ning, C. C., Perrone, L., Pistilli, P., Salvini, P., Santonico, R., Settanta, G., Shen, P. R., Sheng, X. D., Shi, F., Surdo, A., Tan, Y. H., Vallania, P., Vernetto, S., Vigorito, C., Wang, H., Wu, C. Y., Wu, H. R., Xue, L., Yang, Q. Y., Yang, X. C., Yao, Z. G., Yuan, A. F., Zha, M., Zhang, H. M., Zhang, L., Zhang, X. Y., Zhang, Y., Zhao, J., Zhaxiciren, Zhaxisangzhu, Zhou, X. X., Zhu, F. R., and Zhu, Q. Q.
Subjects: High Energy Physics - Experiment, Astrophysics - High Energy Astrophysical Phenomena
Abstract: The ARGO-YBJ experiment is a full-coverage air shower detector located at the Yangbajing Cosmic Ray Observatory (Tibet, People's Republic of China, 4300 m a.s.l.). The high altitude, combined with the full-coverage technique, allows the detection of extensive air showers in a wide energy range and offer the possibility of measuring the cosmic ray proton plus helium spectrum down to the TeV region, where direct balloon/space-borne measurements are available. The detector has been in stable data taking in its full configuration from November 2007 to February 2013. In this paper the measurement of the cosmic ray proton plus helium energy spectrum is presented in the region 3-300 TeV by analyzing the full collected data sample. The resulting spectral index is $\gamma = -2.64 \pm 0.01$. These results demonstrate the possibility of performing an accurate measurement of the spectrum of light elements with a ground based air shower detector., Comment: 18 pages, 8 figures, preprint submitted to Phys. Rev. D
Published: 2015
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25. Search for GeV Gamma Ray Bursts with the ARGO-YBJ Detector: Summary of Eight Years of Observations

Author: Bartoli, B., Bernardini, P., Bi, X. J., Branchini, P., Budano, A., Camarri, P., Cao, Z., Cardarelli, R., Catalanotti, S., Chen, S. Z., Chen, T. L., Creti, P., Cui, S. W., Dai, B. Z., D'Amone, A., Danzengluobu, De Mitri, I., Piazzoli, B. D'Ettorre, Di Girolamo, T., Di Sciascio, G., Feng, C. F., Feng, Zhaoyang, Feng, Zhenyong, Gou, Q. B., Guo, Y. Q., He, H. H., Hu, Haibing, Hu, Hongbo, Iacovacci, M., Iuppa, R., Jia, H. Y., Labaciren, Li, H. J., Liguori, G., Liu, C., Liu, J., Liu, M. Y., Lu, H., Ma, L. L., Ma, X. H., Mancarella, G., Mari, S. M., Marsella, G., Martello, D., Mastroianni, S., Montini, P., Ning, C. C., Panareo, M., Perrone, L., Pistilli, P., Ruggieri, F., Salvini, P., Santonico, R., Shen, P. R., Sheng, X. D., Shi, F., Surdo, A., Tan, Y. H., Vallania, P., Vernetto, S., Vigorito, C., Wang, H., Wu, C. Y., Wu, H. R., Xue, L., Yang, Q. Y., Yang, X. C., Yao, Z. G., Yuan, A. F., Zha, M., Zhang, H. M., Zhang, L., Zhang, X. Y., Zhang, Y., Zhao, J., Zhaxiciren, Zhaxisangzhu, Zhou, X. X., Zhu, F. R., Zhu, Q. Q., and Zizzi, G.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The search for Gamma Ray Burst (GRB) emission in the energy range 1-100 GeV in coincidence with the satellite detection has been carried out using the Astrophysical Radiation with Ground-based Observatory at YangBaJing (ARGO-YBJ) experiment. The high altitude location (4300 m a.s.l.), the large active surface ($\sim$ 6700 m$^2$ of Resistive Plate Chambers), the wide field of view ($\sim 2~$sr, limited only by the atmospheric absorption) and the high duty cycle ($>$ 86 %) make the ARGO-YBJ experiment particularly suitable to detect short and unexpected events like GRBs. With the scaler mode technique, i.e., counting all the particles hitting the detector with no measurement of the primary energy and arrival direction, the minimum threshold of $\sim$ 1 GeV can be reached, overlapping the direct measurements carried out by satellites. During the experiment lifetime, from December 17, 2004 to February 7, 2013, a total of 206 GRBs occurring within the ARGO-YBJ field of view (zenith angle $\theta$ $\le$ 45$^{\circ}$) have been analyzed. This is the largest sample of GRBs investigated with a ground-based detector. Two lightcurve models have been assumed and since in both cases no significant excess has been found, the corresponding fluence upper limits in the 1-100 GeV energy region have been derived, with values as low as 10$^{-5}~$erg cm$^{-2}$. The analysis of a subset of 24 GRBs with known redshift has been used to constrain the fluence extrapolation to the GeV region together with possible cutoffs under different assumptions on the spectrum., Comment: 43 pages, 6 figures, published in APJ
Published: 2015
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26. The Knee of the Cosmic Hydrogen and Helium Spectrum below 1 PeV Measured by ARGO-YBJ and a Cherenkov Telescope of LHAASO

Author: Bartoli, B., Bernardini, P., Bi, X. J., Branchini, P., Budano, A., Camarri, P., Cao, Z., Cardarelli, R., Catalanotti, S., Chen, S. Z., Chen, T. L., Creti, P., Cui, S. W., Dai, B. Z., D'Amone, A., Danzengluobu, De Mitri, I., Piazzoli, B. D'Ettorre, Di Girolamo, T., Di Sciascio, G., Feng, C. F., Feng, Zhaoyang, Feng, Zhenyong, Gou, Q. B., Guo, Y. Q., He, H. H., Hu, Haibing, Hu, Hongbo, Iacovacci, M., Iuppa, R., Jia, H. Y., Labaciren, Li, H. J., Liguori, G., Liu, C., Liu, J., Liu, M. Y., Lu, H., Ma, L. L., Ma, X. H., Mancarella, G., Mari, S. M., Marsella, G., Martello, D., Mastroianni, S., Montini, P., Ning, C. C., Panareo, M., Perrone, L., Pistilli, P., Ruggieri, F., Salvini, P., Santonico, R., Shen, P. R., Sheng, X. D., Shi, F., Surdo, A., Tan, Y. H., Vallania, P., Vernetto, S., Vigorito, C., Wang, H., Wu, C. Y., Wu, H. R., Xue, L., Yang, Q. Y., Yang, X. C., Yao, Z. G., Yuan, A. F., Zha, M., Zhang, H. M., Zhang, L., Zhang, X. Y., Zhang, Y., Zhao, J., Zhaxiciren, Zhaxisangzhu, Zhou, X. X., Zhu, F. R., Zhu, Q. Q., Zizzi, G., Bai, Y. X., Chen, M. J., Chen, Y., Feng, S. H., Gao, B., Gu, M. H., Hou, C., Li, X. X., Liu, J. L., Wang, X., Xiao, G., Zhang, B. K., Zhang, S. S., Zhou, B., and Zuo, X.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, High Energy Physics - Experiment
Abstract: The measurement of cosmic ray energy spectra, in particular for individual species, is an essential approach in finding their origin. Locating the "knees" of the spectra is an important part of the approach and has yet to be achieved. Here we report a measurement of the mixed Hydrogen and Helium spectrum using the combination of the ARGO-YBJ experiment and of a prototype Cherenkov telescope for the LHAASO experiment. A knee feature at 640+/-87 TeV, with a clear steepening of the spectrum, is observed. This gives fundamental inputs to galactic cosmic ray acceleration models.
Published: 2015
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27. Identification of the TeV Gamma-ray Source ARGO J2031+4157 with the Cygnus Cocoon

Author: Collaboration, The ARGO-YBJ, Bartoli, B., Bernardini, P., Bi, X. J., Branchini, P., Budano, A., Camarri, P., Cao, Z., Cardarelli, R., Catalanotti, S., Chen, S. Z., Chen, T. L., Creti, P., Cui, S. W., Dai, B. Z., DAmone, A., Danzengluobu, De Mitri, I., Piazzoli, B. DEttorre, Di Girolamo, T., Di Sciascio, G., Feng, C. F., Feng, Zhaoyang, Feng, Zhenyong, Gou, Q. B., Guo, Y. Q., He, H. H., Hu, Haibing, Hu, Hongbo, Iacovacci, M., Iuppa, R., Jia, H. Y., Labaciren, Li, H. J., Liguori, G., Liu, C., Liu, J., Liu, M. Y., Lu, H., Ma, L. L., Ma, X. H., Mancarella, G., Mari, S. M., Marsella, G., Martello, D., Mastroianni, S., Montini, P., Ning, C. C., Panareo, M., Perrone, L., Pistilli, P., Ruggieri, F., Salvini, P., Santonico, R., Shen, P. R., Sheng, X. D., Shi, F., Surdo, A., Tan, Y. H., Vallania, P., Vernetto, S., Vigorito, C., Wang, H., Wu, C. Y., Wu, H. R., Xue, L., Yang, Q. Y., Yang, X. C., Yao, Z. G., Yuan, A. F., Zha, M., Zhang, H. M., Zhang, L., Zhang, P., Zhang, X. Y., Zhang, Y., Zhao, J., Zhaxiciren, Zhaxisangzhu, Zhou, X. X., Zhu, F. R., Zhu, Q. Q., and Zizzi, G.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The extended TeV gamma-ray source ARGO J2031+4157 (or MGRO J2031+41) is positionally consistent with the Cygnus Cocoon discovered by $Fermi$-LAT at GeV energies in the Cygnus superbubble. Reanalyzing the ARGO-YBJ data collected from November 2007 to January 2013, the angular extension and energy spectrum of ARGO J2031+4157 are evaluated. After subtracting the contribution of the overlapping TeV sources, the ARGO-YBJ excess map is fitted with a two-dimensional Gaussian function in a square region of $10^{\circ}\times 10^{\circ}$, finding a source extension $\sigma_{ext}$= 1$^{\circ}$.8$\pm$0$^{\circ}$.5. The observed differential energy spectrum is $dN/dE =(2.5\pm0.4) \times 10^{-11}(E/1 TeV)^{-2.6\pm0.3}$ photons cm$^{-2}$ s$^{-1}$ TeV$^{-1}$, in the energy range 0.2-10 TeV. The angular extension is consistent with that of the Cygnus Cocoon as measured by $Fermi$-LAT, and the spectrum also shows a good connection with the one measured in the 1-100 GeV energy range. These features suggest to identify ARGO J2031+4157 as the counterpart of the Cygnus Cocoon at TeV energies. The Cygnus Cocoon, located in the star-forming region of Cygnus X, is interpreted as a cocoon of freshly accelerated cosmic rays related to the Cygnus superbubble. The spectral similarity with Supernova Remnants indicates that the particle acceleration inside a superbubble is similar to that in a SNR. The spectral measurements from 1 GeV to 10 TeV allows for the first time to determine the possible spectrum slope of the underlying particle distribution. A hadronic model is adopted to explain the spectral energy distribution., Comment: 16 pages, 3 figures, has been accepted by ApJ for publication
Published: 2014
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28. Energy Spectrum of Cosmic Protons and Helium Nuclei by a Hybrid Measurement at 4300 m a.s.l

Author: Bartoli, B., Bernardini, P., Bi, X. J., Bolognino, I., Branchini, P., Budano, A., Melcarne, A. K. Calabrese, Camarri, P., Cao, Z., Cardarelli, R., Catalanotti, S., Chen, S. Z., Chen, T. L., Creti, P., Cui, S. W., Dai, B. Z., D'Amone, A., Danzengluobu, De Mitri, I., Piazzoli, B. D'Ettorre, Di Girolamo, T., Di Sciascio, G., Feng, C. F., Feng, Zhaoyang, Feng, Zhenyong, Gou, Q. B., Guo, Y. Q., He, H. H., Hu, Haibing, Hu, Hongbo, Iacovacci, M., Iuppa, R., Jia, H. Y., Labaciren, Li, H. J., Liguori, G., Liu, C., Liu, J., Liu, M. Y., Lu, H., Ma, L. L., Ma, X. H., Mancarella, G., Mari, S. M., Marsella, G., Martello, D., Mastroianni, S., Montini, P., Ning, C. C., Panareo, M., Panico, B., Perrone, L., Pistilli8, P., Ruggieri, F., Salvini, P., Santonico, R., Sbano, S. N., Shen, P. R., Sheng, X. D., Shi, F., Surdo, A., Tan, Y. H., Vallania, P., Vernetto, S., Vigorito, C., Wang, H., Wu, C. Y., Wu, H. R., Xue, L., Yang, Q. Y., Yang, X. C., Yao, Z. G., Yuan, A. F., Zha, M., Zhang, H. M., Zhang, L., Zhang, X. Y., Zhang, Y., Zhao, J., Zhaxiciren, Zhaxisangzhu, Zhou, X. X., Zhu, F. R., Zhu, Q. Q., Collaboration, G. Zizzi for ARGO-YBJ, Bai, Y. X., Chen, M. J., Chen, Y., Feng, S. H., Gao, B., Gu, M. H., Hou, C., Li, X. X., Liu, J. L., Wang, X., Xiao, G., Zhang, B. K., Zhang, S. S., Zhou, B., and Collaboration, X. Zuo for LHAASO
Subjects: Astrophysics - High Energy Astrophysical Phenomena, High Energy Physics - Experiment
Abstract: The energy spectrum of cosmic Hydrogen and Helium nuclei has been measured, below the so-called "knee", by using a hybrid experiment with a wide field-of-view Cherenkov telescope and the Resistive Plate Chamber (RPC) array of the ARGO-YBJ experiment at 4300 m above sea level. The Hydrogen and Helium nuclei have been well separated from other cosmic ray components by using a multi-parameter technique. A highly uniform energy resolution of about 25% is achieved throughout the whole energy range (100 TeV - 700 TeV). The observed energy spectrum is compatible with a single power law with index gamma=-2.63+/-0.06., Comment: To be published on Chinese Physics C
Published: 2014
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29. TeV gamma-ray survey of the Northern sky using the ARGO-YBJ detector

Author: Collaboration, The ARGO-YBJ, Bartoli, B., Bernardini, P., Bi, X. J., Bolognino, I., Branchini, P., Budano, A., Melcarne, A. K. Calabrese, Camarri, P., Cao, Z., Cardarelli, R., Catalanotti, S., Chen, S. Z., Chen, T. L., Chen, Y., Creti, P., Cui, S. W., Dai, B. Z., DAmone, A., Danzengluobu, De Mitri, I., Piazzoli, B. DEttorre, Di Girolamo, T., Ding, X. H., Di Sciascio, G., Feng, C. F., Feng, Zhaoyang, Feng, Zhenyong, Gou, Q. B., Guo, Y. Q., He, H. H., Hu, Haibing, Hu, Hongbo, Huang, Q., Iacovacci, M., Iuppa, R., Jia, H. Y., Labaciren, Li, H. J., Li, J. Y., Li, X. X., Liguori, G., Liu, C., Liu, C. Q., Liu, J., Liu, M. Y., Lu, H., Ma, L. L., Ma, X. H., Mancarella, G., Mari, S. M., Marsella, G., Martello, D., Mastroianni, S., Montini, P., Ning, C. C., Panareo, M., Panico, B., Perrone, L., Pistilli, P., Ruggieri, F., Salvini, P., Santonico, R., Sbano, S. N., Shen, P. R., Sheng, X. D., Shi, F., Surdo, A., Tan, Y. H., Vallania, P., Vernetto, S., Vigorito, C., Wang, B., Wang, H., Wu, C. Y., Wu, H. R., Xu, B., Xue, L., Yang, Q. Y., Yang, X. C., Yao, Z. G., Yuan, A. F., Zha, M., Zhang, H. M., Zhang, Jilong, Zhang, Jianli, Zhang, L., Zhang, P., Zhang, X. Y., Zhang, Y., Zhao, J., Zhaxiciren, Zhaxisangzhu, Zhou, X. X., Zhu, F. R., Zhu, Q. Q., and Zizzi, G.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The ARGO-YBJ detector is an extensive air shower array that has been used to monitor the northern $\gamma$-ray sky at energies above 0.3 TeV from 2007 November to 2013 January. In this paper, we present the results of a sky survey in the declination band from $-10^{\circ}$ to $70^{\circ}$, using data recorded over the past five years. With an integrated sensitivity ranging from 0.24 to $\sim$1 Crab units depending on the declination, six sources have been detected with a statistical significance greater than 5 standard deviations. Several excesses are also reported as potential $\gamma$-ray emitters. The features of each source are presented and discussed. Additionally, $95\%$ confidence level upper limits of the flux from the investigated sky region are shown. Specific upper limits for 663 GeV $\gamma$-ray AGNs inside the ARGO-YBJ field of view are reported. The effect of the absorption of $\gamma$-rays due to the interaction with extragalactic background light is estimated., Comment: 30 pages, 13 figures, Accepted for publication by ApJ
Published: 2013
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30. Observation of TeV gamma-rays from the unidentified source HESS J1841-055 with the ARGO-YBJ experiment

Author: Collaboration, The ARGO-YBJ, Bartoli, B., Bernardini, P., Bi, X. J., Bolognino, I., Branchini, P., Budano, A., Melcarne, A. K. Calabrese, Camarri, P., Cao, Z., Cardarelli, R., Catalanotti, S., Cattaneo, C., Chen, S. Z., Chen, T. L., Chen, Y., Creti, P., Cui, S. W., Dai, B. Z., Staiti, G. DAli, DAmone, A., Danzengluobu, De Mitri, I., Piazzoli, B. DEttorre, Di Girolamo, T., Ding, X. H., Di Sciascio, G., Feng, C. F., Feng, Zhaoyang, Feng, Zhenyong, Galeazzi, F., Giroletti, E., Gou, Q. B., Guo, Y. Q., He, H. H., Hu, Haibing, Hu, Hongbo, Huang, Q., Iacovacci, M., Iuppa, R., James, I., Jia, H. Y., Labaciren, Li, H. J., Li, J. Y., Li, X. X., Liguori, G., Liu, C., Liu, C. Q., Liu, J., Liu, M. Y., Lu, H., Ma, L. L., Ma, X. H., Mancarella, G., Mari, S. M., Marsella, G., Martello, D., Mastroianni, S., Montini, P., Ning, C. C., Pagliaro, A., Panareo, M., Panico, B., Perrone, L., Pistilli, P., Ruggieri, F., Salvini, P., Santonico, R., Sbano, S. N., Shen, P. R., Sheng, X. D., Shi, F., Surdo, A., Tan, Y. H., Vallania, P., Vernetto, S., Vigorito, C., Wang, B., Wang, H., Wu, C. Y., Wu, H. R., Xu, B., Xue, L., Yang, Q. Y., Yang, X. C., Yao, Z. G., Yuan, A. F., Zha, M., Zhang, H. M., Zhang, Jilong, Zhang, Jianli, Zhang, L., Zhang, P., Zhang, X. Y., Zhang, Y., Zhao, J., Zhaxiciren, Zhaxisangzhu, Zhou, X. X., Zhu, F. R., Zhu, Q. Q., and Zizzi, G.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We report the observation of a very high energy \gamma-ray source, whose position is coincident with HESS J1841-055. This source has been observed for 4.5 years by the ARGO-YBJ experiment from November 2007 to July 2012. Its emission is detected with a statistical significance of 5.3 standard deviations. Parameterizing the source shape with a two-dimensional Gaussian function we estimate an extension \sigma=(0.40(+0.32,-0.22}) degree, consistent with the HESS measurement. The observed energy spectrum is dN/dE =(9.0-+1.6) x 10^{-13}(E/5 TeV)^{-2.32-+0.23} photons cm^{-2} s^{-1} TeV^{-1}, in the energy range 0.9-50 TeV. The integral \gamma-ray flux above 1 TeV is 1.3-+0.4 Crab units, which is 3.2-+1.0 times the flux derived by HESS. The differences in the flux determination between HESS and ARGO-YBJ, and possible counterparts at other wavelengths are discussed., Comment: 17 pages, 4 figures, have been accepted for publication in ApJ
Published: 2013
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31. Long-term Monitoring on Mrk 501 for Its VHE gamma Emission and a Flare in October 2011

Author: Collaboration, The ARGO-YBJ, Bartoli, B., Bernardini, P., Bi, X. J., Bleve, C., Bolognino, I., Branchini, P., Budano, A., Melcarne, A. K. Calabrese, Camarri, P., Cao, Z., Cardarelli, R., Catalanotti, S., Cattaneo, C., Chen, S. Z., Chen, T. L., Chen, Y., Creti, P., Cui, S. W., Dai, B. Z., Staiti, G. DAl, Danzengluobu, Dattoli, M., De Mitri, I., Piazzoli, B. D Ettorre, Di Girolamo, T., Ding, X. H., Di Sciascio, G., Feng, C. F., Feng, Zhaoyang, Feng, Zhenyong, Galeazzi, F., Giroletti, E., Gou, Q. B., Guo, Y. Q., He, H. H., Hu, Haibing, Hu, Hongbo, Huang, Q., Iacovacci, M., Iuppa, R., James, I., Jia, H. Y., Labaciren, Li, H. J., Li, J. Y., Li, X. X., Liguori, G., Liu, C., Liu, C. Q., Liu, J., Liu, M. Y., Lu, H., Ma, L. L., Ma, X. H., Mancarella, G., Mari, S. M., Marsella, G., Martello, D., Mastroianni, S., Montini, P., Ning, C. C., Pagliaro, A., Panareo, M., Panico, B., Perrone, L., Pistilli, P., Ruggieri, F., Salvini, P., Santonico, R., Shen, P. R., Sheng, X. D., Shi, F., Stanescu, C., Surdo, A., Tan, Y. H., Vallania, P., Vernetto, S., Vigorito, C., Wang, B., Wang, H., Wu, C. Y., Wu, H. R., Xu, B., Xue, L., Yang, Q. Y., Yang, X. C., Yao, Z. G., Yuan, A. F., Zha, M., Zhang, H. M., Zhang, Jilong, Zhang, Jianli, Zhang, L., Zhang, P., Zhang, X. Y., Zhang, Y., Zhao, J., Zhaxiciren, Zhaxisangzhu, Zhou, X. X., Zhu, F. R., Zhu, Q. Q., and Zizzi, G.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: As one of the brightest active blazars in both X-ray and very high energy $\gamma$-ray bands, Mrk 501 is very useful for physics associated with jets from AGNs. The ARGO-YBJ experiment is monitoring it for $\gamma$-rays above 0.3 TeV since November 2007. Starting from October 2011 the largest flare since 2005 is observed, which lasts to about April 2012. In this paper, a detailed analysis is reported. During the brightest $\gamma$-rays flaring episodes from October 17 to November 22, 2011, an excess of the event rate over 6 $\sigma$ is detected by ARGO-YBJ in the direction of Mrk 501, corresponding to an increase of the $\gamma$-ray flux above 1 TeV by a factor of 6.6$\pm$2.2 from its steady emission. In particular, the $\gamma$-ray flux above 8 TeV is detected with a significance better than 4 $\sigma$. Based on time-dependent synchrotron self-Compton (SSC) processes, the broad-band energy spectrum is interpreted as the emission from an electron energy distribution parameterized with a single power-law function with an exponential cutoff at its high energy end. The average spectral energy distribution for the steady emission is well described by this simple one-zone SSC model. However, the detection of $\gamma$-rays above 8 TeV during the flare challenges this model due to the hardness of the spectra. Correlations between X-rays and $\gamma$-rays are also investigated., Comment: have been accepted for publication at ApJ
Published: 2012
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32. Observation of TeV gamma rays from the Cygnus region with the ARGO-YBJ experiment

Author: Bartoli, B., Bernardini, P., Bi, X. J., Bleve, C., Bolognino, I., Branchini, P., Budano, A., Melcarne, A. K. Calabrese, Camarri, P., Cao, Z., Cardarelli, R., Catalanotti, S., Cattaneo, C., Chen, S. Z., Chen, T. L., Chen, Y., Creti, P., Cui, S. W., Dai, B. Z., Staiti, G. D'Alí, Danzengluobu, Dattoli, M., De Mitri, I., Piazzoli, B. D'Ettorre, Di Girolamo, T., Ding, X. H., Di Sciascio, G., Feng, C. F., Feng, Zhaoyang, Feng, Zhenyong, Galeazzi, F., Giroletti, E., Gou, Q. B., Guo, Y. Q., He, H. H., Hu, Haibing, Hu, Hongbo, Huang, Q., Iacovacci, M., Iuppa, R., James, I., Jia, H. Y., Labaciren, Li, H. J., Li, J. Y., Li, X. X., Liguori, G., Liu, C., Liu, C. Q., Liu, J., Liu, M. Y., Lu, H., Ma, L. L., Ma, X. H., Mancarella, G., Mari, S. M., Marsella, G., Martello, D., Mastroianni, S., Montini, P., Ning, C. C., Pagliaro, A., Panareo, M., Panico, B., Perrone, L., Pistilli, P., Ruggieri, F., Salvini, P., Santonico, R., Shen, P. R., Sheng, X. D., Shi, F., Stanescu, C., Surdo, A., Tan, Y. H., Vallania, P., Vernetto, S., Vigorito, C., Wang, B., Wang, H., Wu, C. Y., Wu, H. R., Xu, B., Xue, L., Yang, Q. Y., Yang, X. C., Yao, Z. G., Yuan, A. F., Zha, M., Zhang, H. M., Zhang, Jilong, Zhang, Jianli, Zhang, L., Zhang, P., Zhang, X. Y., Zhang, Y., Zhao, J., Zhaxiciren, Zhaxisangzhu, Zhou, X. X., Zhu, F. R., Zhu, Q. Q., and Zizzi, G.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We report the observation of TeV gamma-rays from the Cygnus region using the ARGO-YBJ data collected from 2007 November to 2011 August. Several TeV sources are located in this region including the two bright extended MGRO J2019+37 and MGRO J2031+41. According to the Milagro data set, at 20 TeV MGRO J2019+37 is the most significant source apart from the Crab Nebula. No signal from MGRO J2019+37 is detected by the ARGO-YBJ experiment, and the derived flux upper limits at 90% confidence level for all the events above 600 GeV with medium energy of 3 TeV are lower than the Milagro flux, implying that the source might be variable and hard to be identified as a pulsar wind nebula. The only statistically significant (6.4 standard deviations) gamma-ray signal is found from MGRO J2031+41, with a flux consistent with the measurement by Milagro., Comment: 14 pages, 4 figures
Published: 2012
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33. Long-term monitoring of the TeV emission from Mrk 421 with the ARGO-YBJ experiment

Author: Collaboration, The ARGO-YBJ, Bartoli, B., Bernardini, P., Bi, X. J., Bleve, C., Bolognino, I., Branchini, P., Budano, A., Melcarne, A. K. Calabrese, Camarri, P., Cao, Z., Cappa, A., Cardarelli, R., Catalanotti, S., Cattaneo, C., Celio, P., Chen, S. Z., Chen, T. L., Chen, Y., Creti, P., Cui, S. W., Dai, B. Z., Staiti, G. D'Alí, Danzengluobu, Dattoli, M., De Mitri, I., Piazzoli, B. D'Ettorre, Di Girolamo, T., Ding, X. H., Di Sciascio, G., Feng, C. F., Feng, Zhaoyang, Feng, Zhenyong, Galeazzi, F., Galeotti, P., Giroletti, E., Gou, Q. B., Guo, Y. Q., He, H. H., Hu, Haibing, Hu, Hongbo, Huang, Q., Iacovacci, M., Iuppa, R., James, I., Jia, H. Y., Labaciren, Li, H. J., Li, J. Y., Li, X. X., Liguori, G., Liu, C., Liu, C. Q., Liu, J., Liu, M. Y., Lu, H., Ma, X. H., Mancarella, G., Mari, S. M., Marsella, G., Martello, D., Mastroianni, S., Montini, P., Ning, C. C., Pagliaro, A., Panareo, M., Panico, B., Perrone, L., Pistilli, P., Qu, X. B., Rossi, E., Ruggieri, F., Salvini, P., Santonico, R., Shen, P. R., Sheng, X. D., Shi, F., Stanescu, C., Surdo, A., Tan, Y. H., Vallania, P., Vernetto, S., Vigorito, C., Wang, B., Wang, H., Wu, C. Y., Wu, H. R., Xu, B., Xue, L., Yan, Y. X., Yang, Q. Y., Yang, X. C., Yao, Z. G., Yuan, A. F., Zha, M., Zhang, H. M., Zhang, Jilong, Zhang, Jianli, Zhang, L., Zhang, P., Zhang, X. Y., Zhang, Y., Zhaxiciren, Zhaxisangzhu, Zhou, X. X., Zhu, F. R., Zhu, Q. Q., and Zizzi, G.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: ARGO-YBJ is an air shower detector array with a fully covered layer of resistive plate chambers. It is operated with a high duty cycle and a large field of view. It continuously monitors the northern sky at energies above 0.3 TeV. In this paper, we report a long-term monitoring of Mrk 421 over the period from 2007 November to 2010 February. This source was observed by the satellite-borne experiments Rossi X-ray Timing Explorer and Swift in the X-ray band. Mrk 421 was especially active in the first half of 2008. Many flares are observed in both X-ray and gamma-ray bands simultaneously. The gamma-ray flux observed by ARGO-YBJ has a clear correlation with the X-ray flux. No lag between the X-ray and gamma-ray photons longer than 1 day is found. The evolution of the spectral energy distribution is investigated by measuring spectral indices at four different flux levels. Hardening of the spectra is observed in both X-ray and gamma-ray bands. The gamma-ray flux increases quadratically with the simultaneously measured X-ray flux. All these observational results strongly favor the synchrotron self-Compton process as the underlying radiative mechanism., Comment: 30 pages, 8 figures
Published: 2011
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34. Mean Interplanetary Magnetic Field Measurement Using the ARGO-YBJ Experiment

Author: Aielli, G., Bacci, C., Bartoli, B., Bernardini, P., Bi, X. J., Bleve, C., Branchini, P., Budano, A., Bussino, S., Melcarne, A. K. Calabrese, Camarri, P., Cao, Z., Cappa, A., Cardarelli, R., Catalanotti, S., Cattaneo, C., Celio, P., Chen, S. Z., Chen, T. L., Chen, Y., Creti, P., Cui, S. W., Dai, B. Z., Staiti, G. D'Alí, Danzengluobu, Dattoli, M., De Mitri, I., Piazzoli, B. D'Ettorre, De Vincenzi, M., Di Girolamo, T., Ding, X. H., Di Sciascio, G., Feng, C. F., Feng, Z. Y., Feng, Zhenyong, Galeazzi, F., Galeotti, P., Gargana, R., Gou, Q. B., Guo, Y. Q., He, H. H., Hu, Haibing, Hu, Hongbo, Huang, Q., Iacovacci, M., Iuppa, R., James, I., Jia, H. Y., Labaciren, Li, H. J., Li, J. Y., Li, X. X., Liberti, B., Liguori, G., Liu, C., Liu, C. Q., Liu, M. Y., Liu, J., Lu, H., Ma, X. H., Mancarella, G., Mari, S. M., Marsella, G., Martello, D., Mastroianni, S., Meng, X. R., Montini, P., Ning, C. C., Pagliaro, A., Panareo, M., Perrone, L., Pistilli, P., Qu, X. B., Rossi, E., Ruggieri, F., Saggese, L., Salvini, P., Santonico, R., Shen, P. R., Sheng, X. D., Shi, F., Stanescu, C., Surdo, A., Tan, Y. H., Vallania, P., Vernetto, S., Vigorito, C., Wang, B., Wang, H., Wu, C. Y., Wu, H. R., Yao, Z. G., Xu, B., Xue, L., Yan, Y. X., Yang, Q. Y., Yang, X. C., Yuan, A. F., Zha, M., Zhang, H. M., Zhang, JiLong, Zhang, JianLi, Zhang, L., Zhang, P., Zhang, X. Y., Zhang, Y., Zhaxisangzhu, Zhaxiciren, Zhou, X. X., Zhu, F. R., Zhu, Q. Q., and Zizzi, G.
Subjects: Astrophysics - Solar and Stellar Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, High Energy Physics - Experiment
Abstract: The sun blocks cosmic ray particles from outside the solar system, forming a detectable shadow in the sky map of cosmic rays detected by the ARGO-YBJ experiment in Tibet. Because the cosmic ray particles are positive charged, the magnetic field between the sun and the earth deflects them from straight trajectories and results in a shift of the shadow from the true location of the sun. Here we show that the shift measures the intensity of the field which is transported by the solar wind from the sun to the earth., Comment: 6 papges,3 figures
Published: 2011
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35. EAS age determination from the study of the lateral distribution of charged particles near the shower axis with the ARGO-YBJ experiment

Author: YBJ Collaboration, Bartoli, B., Bernardini, P., Bi, X. J., Cao, Z., Catalanotti, S., Chen, S. Z., Chen, T. L., Cui, S. W., Dai, B. Z., D'Amone, A., Danzengluobu, De Mitri, I., Piazzoli, B. D'Ettorre, Di Girolamo, T., Di Sciascio, G., Feng, C. F., Feng, Zhaoyang, Feng, Zhenyong, Gou, Q. B., Guo, Y. Q., He, H. H., Hu, Haibing, Hu, Hongbo, Iacovacci, M., Iuppa, R., Jia, H. Y., Labaciren, Li, H. J., Liu, C., Liu, J., Liu, M. Y., Lu, H., Ma, L. L., Ma, X. H., Mancarella, G., Mari, S. M., Marsella, G., Mastroianni, S., Montini, P., Ning, C. C., Perrone, L., Pistilli, P., Salvini, P., Santonico, R., Shen, P. R., Sheng, X. D., Shi, F., Surdo, A., Tan, Y. H., Vallania, P., Vernetto, S., Vigorito, C., Wang, H., Wu, C. Y., Wu, H. R., Xue, L., Yang, Q. Y., Yang, X. C., Yao, Z. G., Yuan, A. F., Zha, M., Zhang, H. M., Zhang, L., Zhang, X. Y., Zhang, Y., Zhao, J., Zhaxiciren, Zhaxisangzhu, Zhou, X. X., Zhu, F. R., Zhu, Q. Q., Bartoli, B., Bernardini, P., Bi, X. J., Cao, Z., Catalanotti, S., Chen, S. Z., Chen, T. L., Cui, S. W., Dai, B. Z., D'Amone, A., Danzengluobu, Null, De Mitri, I., D'Ettorre Piazzoli, B., Di Girolamo, T., Di Sciascio, G., Feng, C. F., Feng, Zhaoyang, Feng, Zhenyong, Gou, Q. B., Guo, Y. Q., He, H. H., Hu, Haibing, Hu, Hongbo, Iacovacci, M., Iuppa, R., Jia, H. Y., Labaciren, Null, Li, H. J., Liu, C., Liu, J., Liu, M. Y., Lu, H., Ma, L. L., Ma, X. H., Mancarella, G., Mari, S. M., Marsella, G., Mastroianni, S., Montini, P., Ning, C. C., Perrone, L., Pistilli, P., Salvini, P., Santonico, R., Shen, P. R., Sheng, X. D., Shi, F., Surdo, A., Tan, Y. H., Vallania, P., Vernetto, S., Vigorito, C., Wang, H., Wu, C. Y., Wu, H. R., Xue, L., Yang, Q. Y., Yang, X. C., Yao, Z. G., Yuan, A. F., Zha, M., Zhang, H. M., Zhang, L., Zhang, X. Y., Zhang, Y., Zhao, J., Zhaxiciren, Null, Zhaxisangzhu, Null, Zhou, X. X., Zhu, F. R., and Zhu, Q. Q.
Subjects: Shower age, Physics::Instrumentation and Detectors, Astrophysics::High Energy Astrophysical Phenomena, Extensive air shower, FOS: Physical sciences, Cosmic ray, 01 natural sciences, High Energy Physics - Experiment, Nuclear physics, High Energy Physics - Experiment (hep-ex), 0103 physical sciences, Wide dynamic range, Extensive air showers, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, Cosmic rays, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Range (particle radiation), 010308 nuclear & particles physics, Detector, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, Charged particle, Computational physics, Distribution function, Air shower, Particle, Composition, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: The ARGO-YBJ experiment, a full coverage extensive air shower (EAS) detector located at high altitude (4300 m a.s.l.) in Tibet, China, has smoothly taken data, with very high stability, since November 2007 to the beginning of 2013. The array consisted of a carpet of about 7000 m2 Resistive Plate Chambers (RPCs) operated in streamer mode and equipped with both digital and analog readout, providing the measurement of particle densities up to few particles per cm2. The unique detector features (full coverage, readout granularity, wide dynamic range, ..) and location (very high altitude) allowed a detailed study of the lateral density profile of charged particles at ground very close to the shower axis and its description by a proper lateral distribution function (LDF). In particular, the information collected in the first 10 m from the shower axis have been shown to provide a very effective tool for the determination of the shower development stage ("age") in the energy range 50 TeV - 10 PeV. The sensitivity of the age parameter to the mass composition of primary Cosmic Rays is also discussed.
Published: 2017

36. Knee of the cosmic hydrogen and helium spectrum below 1 PeV measured by ARGO-YBJ and a Cherenkov telescope of LHAASO

Author: Bartoli, B., Bernardini, P., Bi, X. J., Branchini, P., Budano, A., Camarri, P., Cao, Z., Cardarelli, R., Catalanotti, S., Chen, S. Z., Chen, T. L., Creti, P., Cui, S. W., Dai, B. Z., D Amone, A., Danzengluobu, Mitri, I., D Ettorre Piazzoli, B., Di Girolamo, T., Di Sciascio, G., Feng, C. F., Feng, Zhaoyang, Feng, Zhenyong, Gou, Q. B., Guo, Y. Q., He, H. H., Hu, Haibing, Hu, Hongbo, Iacovacci, M., Iuppa, R., Jia, H. Y., Labaciren, Li, H. J., Liguori, G., Liu, C., Liu, J., Liu, M. Y., Lu, H., Ma, L. L., Ma, X. H., Mancarella, G., Mari, S. M., Marsella, G., Martello, D., Mastroianni, S., Montini, P., Ning, C. C., Panareo, M., Perrone, L., Pistilli, P., Ruggieri, F., Salvini, P., Santonico, R., Shen, P. R., Sheng, X. D., Shi, F., Surdo, A., Tan, Y. H., Piero Vallania, Vernetto, S., Vigorito, C., Wang, H., Wu, C. Y., Wu, H. R., Xue, L., Yang, Q. Y., Yang, X. C., Yao, Z. G., Yuan, A. F., Zha, M., Zhang, H. M., Zhang, L., Zhang, X. Y., Zhang, Y., Zhao, J., Zhaxiciren, Zhaxisangzhu, Zhou, X. X., Zhu, F. R., Zhu, Q. Q., Zizzi, G., Bai, Y. X., Chen, M. J., Chen, Y., Feng, S. H., Gao, B., Gu, M. H., Hou, C., Li, X. X., Liu, J. L., Wang, X., Xiao, G., Zhang, B. K., Zhang, S. S., Zhou, B., Zuo, X., Bartoli, B., Bernardini, P., Bi, X. J., Cao, Z., Catalanotti, S., Chen, S. Z., Chen, T. L., Cui, S. W., Dai, B. Z., D'Amone, A., Danzengluobu, Null, De Mitri, I., D'Ettorre Piazzoli, B., Di Girolamo, T., Di Sciascio, G., Feng, C. F., Feng, Zhaoyang, Feng, Zhenyong, Guo, Q. B., Guo, Y. Q., He, H. H., Hu, Haibing, Hu, Hongbo, Iacovacci, M., Iuppa, R., Jia, H. Y., Labaciren, Null, Li, H. J., Liu, C., Liu, J., Liu, M. Y., Lu, H., Ma, L. L., Ma, X. H., Mancarella, G., Mari, S. M., Marsella, G., Mastroianni, S., Montini, P., Ning, C. C., Perrone, L., Pistilli, P., Salvini, P., Santonico, R., Shen, P. R., Sheng, X. D., Shi, F., Surdo, A., Tan, Y. H., Vallania, P., Vernetto, S., Vigorito, C., Wang, H., Wu, C. Y., Wu, H. R., Xue, L., Yang, Q. Y., Yang, X. C., Yao, Z. G., Yuan, A. F., Zha, M., Zhang, H. M., Zhang, L., Zhang, X. Y., Zhang, Y., Zhao, J., Zhaxiciren, Null, Zhaxisangzhu, Null, Zhou, X. X., Zhu, F. R., Zhu, Q. Q., Bai, Y. X., Chen, M. J., Feng, S. H., Gao, B., Gu, M. H., Hou, C., Liu, J. L., Wang, X., Xiao, G., Zhang, B. K., Zhang, S. S., Zhou, B., Zuo, X., ITA, Bartoli, Bruno, Bi, X. . j., Catalanotti, Sergio, Chen, S. . z., Chen, T. . l., Cui, S. . w., Dai, B. z, D’Amone, A., D'ETTORRE PIAZZOLI, Benedetto, DI GIROLAMO, Tristano, Feng, C. . f., Guo, Q. . b., Guo, Y. . q., He, H. . h., Iacovacci, Michele, Jia, H. . y., Li, H. . j., Liu, M. . y., Ma, L. . l., Ma, X. . h., Mari, S. . m., Ning, C. . c., Shen, P. . r., Sheng, X. . d., Tan, Y. . h., Wu, C. . y., Wu, H. . r., Yang, Q. . y., Yang, X. . c., Yao, Z. . g., Yuan, A. . f., Zhang, H. . m., Zhang, X. . y., Zhou, X. . x., Zhu, F. . r., Zhu, Q. . q., Bai, Y. . x., Chen, M. . j., Feng, S. . h., Gu, M. . h., Liu, J. . l., Zhang, B. . k., Zhang, S. . s., B., Bartoli, P., Bernardini, X. J., Bi, Z., Cao, S., Catalanotti, S. Z., Chen, T. L., Chen, S. W., Cui, B. Z., Dai, D, A., ’, Amone, Danzengluobu, I. De, Mitri, D, B., Ettorre, Piazzoli, T. Di, Girolamo, G. Di, Sciascio, C. F., Feng, Zhaoyang, Feng, Zhenyong, Feng, Q. B., Guo, Y. Q., Guo, H. H., He, Haibing, Hu, Hongbo, Hu, M., Iacovacci, R., Iuppa, H. Y., Jia, Labaciren, H. J., Li, C., Liu, J., Liu, M. Y., Liu, H., Lu, L. L., Ma, X. H., Ma, G., Mancarella, Mari, Stefano Maria, G., Marsella, S., Mastroianni, Montini, Paolo, C. C., Ning, L., Perrone, P., Pistilli, P., Salvini, R., Santonico, P. R., Shen, X. D., Sheng, F., Shi, A., Surdo, Y. H., Tan, P., Vallania, S., Vernetto, C., Vigorito, H., Wang, C. Y., Wu, H. R., Wu, L., Xue, Q. Y., Yang, X. C., Yang, Z. G., Yao, A. F., Yuan, M., Zha, H. M., Zhang, L., Zhang, X. Y., Zhang, Y., Zhang, J., Zhao, Zhaxiciren, Zhaxisangzhu, X. X., Zhou, F. R., Zhu, Q. Q., Zhu, Y. X., Bai, M. J., Chen, S. H., Feng, B., Gao, M. H., Gu, C., Hou, J. L., Liu, X., Wang, G., Xiao, B. K., Zhang, S. S., Zhang, B., Zhou, and Collaboratio, (LHAASO
Subjects: Nuclear and High Energy Physics, Proton, Astrophysics::High Energy Astrophysical Phenomena, Cosmic microwave background, FOS: Physical sciences, Cosmic ray, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Cosmic Ray, Helium, Spectral line, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), 0103 physical sciences, 010303 astronomy & astrophysics, Cherenkov radiation, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Spectral index, 010308 nuclear & particles physics, Astrophysics::Instrumentation and Methods for Astrophysics, 13. Climate action, Production (computer science), Astrophysics - High Energy Astrophysical Phenomena, Energy (signal processing), proton
Abstract: The measurement of the cosmic ray energy spectrum, in particular for individual species of nuclei, is an important tool to investigate cosmic ray production and propagation mechanisms. The determination of the ``knees'' in the spectra of different species remains one of the main challenges in cosmic ray physics. In fact, experimental results are still conflicting. In this paper we report a measurement of the mixed proton and helium energy spectrum, obtained with the combined data of the ARGO-YBJ experiment and a wide field of view Cherenkov telescope, a prototype of the future LHAASO experiment. By means of a multiparameter technique, we have selected a high-purity proton plus helium sample. The reconstructed energy resolution is found to be about 25% throughout the investigated energy range from 100 TeV to 3 PeV, with a systematic uncertainty in the absolute energy scale of 9.7%. The found energy spectrum can be fitted with a broken power-law function, with a break at the energy ${\mathrm{E}}_{k}=700\ifmmode\pm\else\textpm\fi{}230(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}70(\mathrm{sys})\text{ }\text{ }\mathrm{TeV}$, where the spectral index changes from $\ensuremath{-}2.56\ifmmode\pm\else\textpm\fi{}0.05$ to $\ensuremath{-}3.24\ifmmode\pm\else\textpm\fi{}0.36$. The statistical significance of the observed spectral break is 4.2 standard deviations.
Published: 2015

37. The cosmic ray proton plus helium energy spectrum measured by the ARGO-YBJ experiment in the energy range 3-300 TeV

Author: Argo-Ybj, The Collaboration, Bartoli, B., Bernardini, P., Bi, X. J., Cao, Z., Catalanotti, S., Chen, S. Z., Chen, T. L., Cui, S. W., Dai, B. Z., D Amone, A., Danzengluobu, Mitri, I., D Ettorre Piazzoli, B., Di Girolamo, T., Di Sciascio, G., Feng, C. F., Feng, Zhaoyang, Feng, Zhenyong, Gou, Q. B., Guo, Y. Q., He, H. H., Hu, Haibing, Hu, Hongbo, Iacovacci, M., Iuppa, R., Jia, H. Y., Labaciren, Li, H. J., Liu, C., Liu, J., Liu, M. Y., Lu, H., Ma, L. L., Ma, X. H., Mancarella, G., Mari, S. M., Marsella, G., Mastroianni, S., Montini, P., Ning, C. C., Perrone, L., Pistilli, P., Salvini, P., Santonico, R., Settanta, G., Shen, P. R., Sheng, X. D., Shi, F., Surdo, A., Tan, Y. H., Piero Vallania, Vernetto, S., Vigorito, C., Wang, H., Wu, C. Y., Wu, H. R., Xue, L., Yang, Q. Y., Yang, X. C., Yao, Z. G., Yuan, A. F., Zha, M., Zhang, H. M., Zhang, L., Zhang, X. Y., Zhang, Y., Zhao, J., Zhaxiciren, Zhaxisangzhu, Zhou, X. X., Zhu, F. R., Zhu, Q. Q., Bartoli, B., Bernardini, P., Bi, X. J., Cao, Z., Catalanotti, S., Chen, S. Z., Chen, T. L., Cui, S. W., Dai, B. Z., D'Amone, A., Danzengluobu, De Mitri, I., D'Ettorre Piazzoli, B., Di Girolamo, T., Di Sciascio, G., Feng, C. F., Feng, Z., Gou, Q. B., Guo, Y. Q., He, H. H., Hu, H., Iacovacci, M., Iuppa, R., Jia, H. Y., Labaciren, Li, H. J., Liu, C., Liu, J., Liu, M. Y., Lu, H., Ma, L. L., Ma, X. H., Mancarella, G., Mari, S. M., Marsella, G., Mastroianni, S., Montini, P., Ning, C. C., Perrone, L., Pistilli, P., Salvini, P., Santonico, R., Settanta, G., Shen, P. R., Sheng, X. D., Shi, F., Surdo, A., Tan, Y. H., Vallania, P., Vernetto, S., Vigorito, C., Wang, H., Wu, C. Y., Wu, H. R., Xue, L., Yang, Q. Y., Yang, X. C., Yao, Z. G., Yuan, A. F., Zha, M., Zhang, H. M., Zhang, L., Zhang, X. Y., Zhang, Y., Zhao, J., Zhaxiciren, Zhaxisangzhu, Zhou, X. X., Zhu, F. R., Zhu, Q. Q., B., Bartoli, Bernardini, Paolo, X. . J., Bi, Z., Cao, S., Catalanotti, Chen, S. . Z., Chen, T. . L., Cui, S. . W., Dai, B. . Z., A., D’Amone, DE MITRI, Ivan, B., D’Ettorre Piazzoli, T., Di Girolamo, G., Di Sciascio, Feng, C. . F., Zhaoyang, Feng, Zhenyong, Feng, Gou, Q. . B., Guo, Y. . Q., H. . H., He, Haibing, Hu, Hongbo, Hu, M., Iacovacci, R., Iuppa, Jia, H. . Y., H. . J., Li, C., Liu, J., Liu, Liu, M. . Y., H., Lu, L. . L., Ma, X. . H., Ma, Mancarella, Giovanni, Mari, S. . M., Marsella, Giovanni, S., Mastroianni, P., Montini, Ning, C. . C., Perrone, Lorenzo, P., Pistilli, P., Salvini, R., Santonico, G., Settanta, Shen, P. . R., Sheng, X. . D., F., Shi, A., Surdo, Tan, Y. . H., P., Vallania, S., Vernetto, C., Vigorito, H., Wang, C. . Y., Wu, H. . R., Wu, L., Xue, Yang, Q. . Y., Yang, X. . C., Yao, Z. . G., Yuan, A. . F., M., Zha, Zhang, H. . M., L., Zhang, Zhang, X. . Y., Y., Zhang, J., Zhao, Zhou, X. . X., Zhu, F. . R., Zhu, Q. . Q., B. Bartoli, BERNARDINI, Paolo, X. .J. Bi, Z. Cao, S. Catalanotti, S. .Z. Chen, T. .L. Chen, S. .W. Cui, B. .Z. Dai, A. D’Amone, B. D’Ettorre Piazzoli, T. Di Girolamo, G. Di Sciascio, C. .F. Feng, Zhaoyang Feng, Zhenyong Feng, Q. .B. Gou, Y. .Q. Guo, H. .H. He, Haibing Hu, Hongbo Hu, M. Iacovacci, R. Iuppa, H. .Y. Jia, H. .J. Li, C. Liu, J. Liu, M. .Y. Liu, H. Lu, L. .L. Ma, X. .H. Ma, MANCARELLA, Giovanni, S. .M. Mari, MARSELLA, GIOVANNI, S. Mastroianni, P. Montini, C. .C. Ning, PERRONE, Lorenzo, P. Pistilli, P. Salvini, R. Santonico, G. Settanta, P. .R. Shen, X. .D. Sheng, F. Shi, A. Surdo, Y. .H. Tan, P. Vallania, S. Vernetto, C. Vigorito, H. Wang, C. .Y. Wu, H. .R. Wu, L. Xue, Q. .Y. Yang, X. .C. Yang, Z. .G. Yao, A. .F. Yuan, M. Zha, H. .M. Zhang, L. Zhang, X. .Y. Zhang, Y. Zhang, J. Zhao, X. .X. Zhou, F. .R. Zhu, Q. .Q. Zhu, Bartoli, Bruno, Bi, X. . j., Catalanotti, Sergio, Chen, S. . z., Chen, T. . l., Cui, S. . w., Dai, B. . z., D’Amone, A., Danzengluobu, Null, D'ETTORRE PIAZZOLI, Benedetto, DI GIROLAMO, Tristano, Feng, C. . f., Feng, Zhaoyang, Feng, Zhenyong, Gou, Q. . b., Guo, Y. . q., He, H. . h., Hu, Haibing, Hu, Hongbo, Iacovacci, Michele, Jia, H. . y., Labaciren, Null, Li, H. . j., Liu, M. . y., Ma, L. . l., Ma, X. . h., Mari, S. . m., Ning, C. . c., Shen, P. . r., Sheng, X. . d., Tan, Y. . h., Wu, C. . y., Wu, H. . r., Yang, Q. . y., Yang, X. . c., Yao, Z. . g., Yuan, A. . f., Zhang, H. . m., Zhang, X. . y., Zhaxiciren, Null, Zhaxisangzhu, Null, Zhou, X. . x., Zhu, F. . r., Zhu, Q. . q., Mari, Stefano Maria, The ARGO YBJ, Collaboration, and ITA
Subjects: Nuclear and High Energy Physics, PARTICLE-ACCELERATION, Physics and Astronomy (miscellaneous), Proton, Astrophysics::High Energy Astrophysical Phenomena, SHELL, FOS: Physical sciences, Cosmic ray, Astrophysics, 01 natural sciences, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), Observatory, 0103 physical sciences, Ultra-high-energy cosmic ray, 010306 general physics, Cosmic-ray observatory, DETECTOR, Nuclear and High Energy Physic, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), AIR-SHOWERS, Spectral index, 010308 nuclear & particles physics, Astrophysics::Instrumentation and Methods for Astrophysics, Spectral density, Air shower, 13. Climate action, SUPERNOVA REMNANT, High Energy Physics::Experiment, Astrophysics - High Energy Astrophysical Phenomena
Abstract: The ARGO-YBJ experiment is a full-coverage air shower detector located at the Yangbajing Cosmic Ray Observatory (Tibet, People's Republic of China, 4300 m a.s.l.). The high altitude, combined with the full-coverage technique, allows the detection of extensive air showers in a wide energy range and offer the possibility of measuring the cosmic ray proton plus helium spectrum down to the TeV region, where direct balloon/space-borne measurements are available. The detector has been in stable data taking in its full configuration from November 2007 to February 2013. In this paper the measurement of the cosmic ray proton plus helium energy spectrum is presented in the region 3-300 TeV by analyzing the full collected data sample. The resulting spectral index is $\gamma = -2.64 \pm 0.01$. These results demonstrate the possibility of performing an accurate measurement of the spectrum of light elements with a ground based air shower detector., Comment: 18 pages, 8 figures, preprint submitted to Phys. Rev. D

38. TeV gamma-ray survey of the Northern sky using the ARGO-YBJ detector

Author: Argo-Ybj, The Collaboration, Bartoli, B., Bernardini, P., Bi, X. J., Bolognino, I., Branchini, P., Budano, A., Calabrese Melcarne, A. K., Camarri, P., Cao, Z., Cardarelli, R., Catalanotti, S., Chen, S. Z., Chen, T. L., Chen, Y., Creti, P., Cui, S. W., Dai, B. Z., Damone, A., Danzengluobu, Mitri, I., Dettorre Piazzoli, B., Di Girolamo, T., Ding, X. H., Di Sciascio, G., Feng, C. F., Feng, Zhaoyang, Feng, Zhenyong, Gou, Q. B., Guo, Y. Q., He, H. H., Hu, Haibing, Hu, Hongbo, Huang, Q., Iacovacci, M., Iuppa, R., Jia, H. Y., Labaciren, Li, H. J., Li, J. Y., Li, X. X., Liguori, G., Liu, C., Liu, C. Q., Liu, J., Liu, M. Y., Lu, H., Ma, L. L., Ma, X. H., Mancarella, G., Mari, S. M., Marsella, G., Martello, D., Mastroianni, S., Montini, P., Ning, C. C., Panareo, M., Panico, B., Perrone, L., Pistilli, P., Ruggieri, F., Salvini, P., Santonico, R., Sbano, S. N., Shen, P. R., Sheng, X. D., Shi, F., Surdo, A., Tan, Y. H., Piero Vallania, Vernetto, S., Vigorito, C., Wang, B., Wang, H., Wu, C. Y., Wu, H. R., Xu, B., Xue, L., Yang, Q. Y., Yang, X. C., Yao, Z. G., Yuan, A. F., Zha, M., Zhang, H. M., Zhang, Jilong, Zhang, Jianli, Zhang, L., Zhang, P., Zhang, X. Y., Zhang, Y., Zhao, J., Zhaxiciren, Zhaxisangzhu, Zhou, X. X., Zhu, F. R., Zhu, Q. Q., Zizzi, G., Bartoli, Bruno, Bernardini, P., X. J., Bi, Bolognino, I., Branchini, P., Budano, A., Calabrese Melcarne, A. K., Camarri, P., Cao, Z., Cardarelli, R., Catalanotti, Sergio, Chen, S. Z., Chen, T. L., Chen, Y., Creti, P., Cui, S. W., Dai, B. Z., D'Amone, A., Danzengluobu, De Mitri, I., D'ETTORRE PIAZZOLI, Benedetto, DI GIROLAMO, Tristano, Ding, X. H., Di Sciascio, G., Feng, C. F., Zhaoyang, Feng, Zhenyong, Feng, Gou, Q. B., Guo, Y. Q., H. H., He, Haibing, Hu, Hongbo, Hu, Huang, Q., Iacovacci, Michele, Iuppa, R., Jia, H. Y., Labaciren, H. J., Li, J. Y., Li, X. X., Li, Liguori, G., Liu, C., Liu, C. Q., Liu, J., Liu, M. Y., Lu, H., L. L., Ma, X. H., Ma, Mancarella, G., Mari, S. M., Marsella, G., Martello, D., Mastroianni, S., Montini, P., Ning, C. C., Panareo, M., Panico, B., Perrone, L., Pistilli, P., Ruggieri, F., Salvini, P., Santonico, R., Sbano, S. N., Shen, P. R., Sheng, X. D., Shi, F., Surdo, A., Tan, Y. H., Vallania, P., Vernetto, S., Vigorito, C., Wang, B., Wang, H., C. Y., Wu, H. R., Wu, Xu, B., Xue, L., Yang, Q. Y., Yang, X. C., Yao, Z. G., Yuan, A. F., Zha, M., Zhang, H. M., Jilong, Zhang, Jianli, Zhang, Zhang, L., Zhang, P., Zhang, X. Y., Zhang, Y., Zhao, J., Zhaxiciren, Zhaxisangzhu, Zhou, X. X., Zhu, F. R., Zhu, Q. Q., Zizzi, and G., B. Bartoli, BERNARDINI, Paolo, X. J. Bi, I. Bolognino, P. Branchini, A. Budano, A. K. Calabrese Melcarne, P. Camarri, Z. Cao, R. Cardarelli, S. Catalanotti, S. Z. Chen, T. L. Chen, Y. Chen, P. Creti, S. W. Cui, B. Z. Dai, D'AMONE, ANTONIO, DE MITRI, Ivan, B. D'Ettorre Piazzoli, T. Di Girolamo, X. H. Ding, G. Di Sciascio, C. F. Feng, Zhaoyang Feng, Zhenyong Feng, Q. B. Gou, Y. Q. Guo, H. H. He, Haibing Hu, Hongbo Hu, Q. Huang, M. Iacovacci, R. Iuppa, H. Y. Jia, H. J. Li, J. Y. Li, X. X. Li, G. Liguori, C. Liu, C. Q. Liu, J. Liu, M. Y. Liu, H. Lu, L. L. Ma, X. H. Ma, MANCARELLA, Giovanni, S. M. Mari, MARSELLA, GIOVANNI, MARTELLO, Daniele, S. Mastroianni, P. Montini, C. C. Ning, PANAREO, Marco, B. Panico, PERRONE, Lorenzo, P. Pistilli, F. Ruggieri, P. Salvini, R. Santonico, S. N. Sbano, P. R. Shen, X. D. Sheng, F. Shi, A. Surdo, Y. H. Tan, P. Vallania, S. Vernetto, C. Vigorito, B. Wang, H. Wang, C. Y. Wu, H. R. Wu, B. Xu, L. Xue, Q. Y. Yang, X. C. Yang, Z. G. Yao, A. F. Yuan, M. Zha, H. M. Zhang, Jilong Zhang, Jianli Zhang, L. Zhang, P. Zhang, X. Y. Zhang, Y. Zhang, J. Zhao, X. X. Zhou, F. R. Zhu, Q. Q. Zhu, G. Zizzi, B., Bartoli, Bernardini, Paolo, I., Bolognino, P., Branchini, A., Budano, A. K., Calabrese Melcarne, P., Camarri, Z., Cao, R., Cardarelli, S., Catalanotti, S. Z., Chen, T. L., Chen, Y., Chen, P., Creti, S. W., Cui, B. Z., Dai, D'Amone, Antonio, B., D'Ettorre Piazzoli, T., Di Girolamo, X. H., Ding, G., Di Sciascio, C. F., Feng, Q. B., Gou, Y. Q., Guo, Q., Huang, M., Iacovacci, R., Iuppa, H. Y., Jia, G., Liguori, C., Liu, C. Q., Liu, J., Liu, M. Y., Liu, H., Lu, Mancarella, Giovanni, S. M., Mari, Marsella, Giovanni, Martello, Daniele, S., Mastroianni, P., Montini, C. C., Ning, Panareo, Marco, B., Panico, Perrone, Lorenzo, P., Pistilli, F., Ruggieri, P., Salvini, R., Santonico, S. N., Sbano, P. R., Shen, X. D., Sheng, F., Shi, A., Surdo, Y. H., Tan, P., Vallania, S., Vernetto, C., Vigorito, B., Wang, H., Wang, B., Xu, L., Xue, Q. Y., Yang, X. C., Yang, Z. G., Yao, A. F., Yuan, M., Zha, H. M., Zhang, L., Zhang, P., Zhang, X. Y., Zhang, Y., Zhang, J., Zhao, X. X., Zhou, F. R., Zhu, Q. Q., Zhu, G., Zizzi, Mari, Stefano Maria, and The ARGO YBJ, Collaboration
Subjects: Astrophysics::High Energy Astrophysical Phenomena, media_common.quotation_subject, FOS: Physical sciences, Flux, Field of view, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Gamma rays: general – surveys, 01 natural sciences, Declination, 0103 physical sciences, Absorption (logic), 010303 astronomy & astrophysics, media_common, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, 010308 nuclear & particles physics, Settore FIS/01 - Fisica Sperimentale, Astrophysics::Instrumentation and Methods for Astrophysics, Gamma ray, Astronomy and Astrophysics, general – su [gamma rays], Air shower, Extragalactic background light, 13. Climate action, Space and Planetary Science, Sky, general – surveys [Gamma rays], Astrophysics - High Energy Astrophysical Phenomena
Abstract: The ARGO-YBJ detector is an extensive air shower array that has been used to monitor the northern $\gamma$-ray sky at energies above 0.3 TeV from 2007 November to 2013 January. In this paper, we present the results of a sky survey in the declination band from $-10^{\circ}$ to $70^{\circ}$, using data recorded over the past five years. With an integrated sensitivity ranging from 0.24 to $\sim$1 Crab units depending on the declination, six sources have been detected with a statistical significance greater than 5 standard deviations. Several excesses are also reported as potential $\gamma$-ray emitters. The features of each source are presented and discussed. Additionally, $95\%$ confidence level upper limits of the flux from the investigated sky region are shown. Specific upper limits for 663 GeV $\gamma$-ray AGNs inside the ARGO-YBJ field of view are reported. The effect of the absorption of $\gamma$-rays due to the interaction with extragalactic background light is estimated., Comment: 30 pages, 13 figures, Accepted for publication by ApJ

39. Search for Gamma-Ray Emission from the Sun during Solar Minimum with the ARGO-YBJ Experiment

Author: C. Y. Wu, Labaciren, Q. Y. Yang, P. Montini, X. H. Ma, C. C. Ning, Haifeng Li, C. Q. Liu, Q. B. Gou, Q. Q. Zhu, L. Zhang, T. L. Chen, Danzengluobu, C. Vigorito, P. Bernardini, R. Santonico, Zhaxisangzhu, Hongbo Hu, Yicheng Guo, A. Surdo, Y. H. Tan, P. R. Shen, X. C. Yang, H. Y. Jia, H. R. Wu, S. Catalanotti, B. Z. Dai, J. Zhao, Huihai He, Zhaoyang Feng, F. R. Zhu, P. Pistilli, H. M. Zhang, H. Lu, Minghui Liu, G. Di Sciascio, X. Y. Zhang, Zihou Li, G. Mancarella, I. De Mitri, T. Di Girolamo, Zhaxiciren, Xiangdong Sheng, R. Iuppa, S. W. Cui, A. F. Yuan, S. Vernetto, S. Z. Chen, A. D'Amone, Cunfeng Feng, H. Wang, S. Mastroianni, Y. J. Zhang, Haibing Hu, B. Bartoli, X. J. Bi, L. Perrone, J. K. K. Liu, L. L. Ma, W. Gao, M. Zha, Zhenyong Feng, X. X. Zhou, P. Vallania, B. D'Ettorre Piazzoli, L. Xue, Z. G. Yao, M. Iacovacci, Zhengguo Cao, F. Shi, P. Salvini, G. Marsella, S. M. Mari, Bartoli B., Bernardini P., Bi X. J., Cao Z., Catalanotti S., Chen S. Z., Chen T. L., Cui S. W., Dai B. Z., D'Amone A., Danzengluobu, Mitri I. D., Piazzoli B. D., Girolamo T. D., Sciascio G. D., Feng C. F., Feng Z., Gao W., Gou Q. B., Guo Y. Q., He H. H., Hu H., Iacovacci M., Iuppa R., Jia H. Y., Labaciren, Li H. J., Li Z., Liu C., Liu J., Liu M. Y., Lu H., Ma L. L., Ma X. H., Mancarella G., Mari S. M., Marsella G., Mastroianni S., Montini P., Ning C. C., Perrone L., Pistilli P., Salvini P., Santonico R., Shen P. R., Sheng X. D., Shi F., Surdo A., Tan Y. H., Vallania P., Vernetto S., Vigorito C., Wang H., Wu C. Y., Wu H. R., Xue L., Yang Q. Y., Yang X. C., Yao Z. G., Yuan A. F., Zha M., Zhang H. M., Zhang L., Zhang X. Y., Zhang Y., Zhao J., Zhaxiciren Zhaxisangzhu, Zhou X. X., Zhu F. R., Zhu Q. Q., Bartoli, B., Bernardini, P., Bi, X. J., Cao, Z., Catalanotti, S., Chen, S. Z., Chen, T. L., Cui, S. W., Dai, B. Z., D'Amone, A., Mitri, I. D., Piazzoli, B. D., Girolamo, T. D., Sciascio, G. D., Feng, C. F., Feng, Z., Gao, W., Gou, Q. B., Guo, Y. Q., He, H. H., Hu, H., Iacovacci, M., Iuppa, R., Jia, H. Y., Li, H. J., Li, Z., Liu, C., Liu, J., Liu, M. Y., Lu, H., Ma, L. L., Ma, X. H., Mancarella, G., Mari, S. M., Marsella, G., Mastroianni, S., Montini, P., Ning, C. C., Perrone, L., Pistilli, P., Salvini, P., Santonico, R., Shen, P. R., Sheng, X. D., Shi, F., Surdo, A., Tan, Y. H., Vallania, P., Vernetto, S., Vigorito, C., Wang, H., Wu, C. Y., Wu, H. R., Xue, L., Yang, Q. Y., Yang, X. C., Yao, Z. G., Yuan, A. F., Zha, M., Zhang, H. M., Zhang, L., Zhang, X. Y., Zhang, Y., Zhao, J., Zhaxiciren, Zhaxisangzhu, Zhou, X. X., Zhu, F. R., Zhu, Q. Q., D’Amone, A., Danzengluobu, Null, Mitri, I. De, Piazzoli, B. D’Ettorre, Di Girolamo, T., Sciascio, G. Di, Feng, Zhaoyang, Feng, Zhenyong, Hu, Haibing, Hu, Hongbo, Labaciren, Null, Zhaxiciren, Null, and Zhaxisangzhu, Null
Subjects: Solar minimum, Sun: general, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Cosmic ray, astroparticle physics, cosmic rays, gamma rays: general, 7. Clean energy, 01 natural sciences, Atmosphere, 0103 physical sciences, general [Sun], 010303 astronomy & astrophysics, Argo, cosmic ray, High Energy Astrophysical Phenomena (astro-ph.HE), Astroparticle physics, Physics, 010308 nuclear & particles physics, Settore FIS/01 - Fisica Sperimentale, Gamma ray, Astronomy, astroparticle physic, Astronomy and Astrophysics, 13. Climate action, Space and Planetary Science, High Energy Physics::Experiment, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, general [gamma rays]
Abstract: The hadronic interaction of cosmic rays with solar atmosphere can produce high energy gamma-rays. The gamma-ray luminosity is correlated both with the flux of primary cosmic rays and the intensity of the solar magnetic field. The gamma-rays below 200 GeV have been observed by Fermi without any evident energy cutoff. The bright gamma-ray flux above 100 GeV has been detected only during solar minimum. The only available data in the TeV range come from the HAWC observations, however, outside the solar minimum. The ARGO-YBJ data set has been used to search for sub-TeV/TeV gamma-rays from the Sun during the solar minimum from 2008 to 2010, the same time period covered by the Fermi data. A suitable model containing the Sun shadow, solar disk emission, and inverse-Compton emission has been developed, and the chi-square minimization method was used to quantitatively estimate the disk gamma-ray signal. The result shows that no significant gamma-ray signal is detected and upper limits to the gamma-ray flux at 0.3-7 TeV are set at the 95% confidence level. In the low energy range these limits are consistent with the extrapolation of the Fermi-LAT measurements taken during solar minimum and are compatible with a softening of the gamma-ray spectrum below 1 TeV. They also provide an experimental upper bound to any solar disk emission at TeV energies. Models of dark matter annihilation via long-lived mediators predicting gamma-ray fluxes >10-7 GeV cm-2 s-1 below 1 TeV are ruled out by the ARGO-YBJ limits.
Published: 2019

40. Galactic Cosmic-Ray Anisotropy in the Northern hemisphere from the ARGO-YBJ Experiment during 2008-2012

Author: J. Zhao, Hongbo Hu, P. R. Shen, X. C. Yang, A. Surdo, Yicheng Guo, Y. H. Tan, Zhaoyang Feng, F. R. Zhu, X. J. Bi, T. Di Girolamo, J. K. K. Liu, S. Vernetto, Zhaxisangzhu, Zhengguo Cao, S. Z. Chen, Q. Q. Zhu, L. Zhang, T. L. Chen, R. Santonico, S. Mastroianni, C. Vigorito, C. Y. Wu, S. W. Cui, C. Q. Liu, Q. B. Gou, C. C. Ning, P. Vallania, F. Shi, S. M. Mari, B. D'Ettorre Piazzoli, A. D'Amone, H. J. Li, H. R. Wu, Zhaxiciren, R. Iuppa, L. Xue, P. Salvini, G. Marsella, W. Gao, P. Bernardini, H. Wang, H. Lu, Danzengluobu, S. Catalanotti, David Ruffolo, A. F. Yuan, B. Z. Dai, Y. J. Zhang, Huihai He, M. Zha, G. Di Sciascio, X. Y. Zhang, Labaciren, Xiangdong Sheng, P. Pistilli, H. M. Zhang, Minghui Liu, I. De Mitri, Q. Y. Yang, P. Montini, X. H. Ma, X. X. Zhou, L. Perrone, Haibing Hu, L. L. Ma, H. Y. Jia, G. Mancarella, B. Bartoli, Cunfeng Feng, M. Iacovacci, Z. G. Yao, Bartoli, B., Bernardini, P., Bi, X. J., Cao, Z., Catalanotti, S., Chen, S. Z., Chen, T. L., Cui, S. W., Dai, B. Z., D’Amone, A., Danzengluobu, Null, De Mitri, I., Piazzoli, B. D’Ettorre, Di Girolamo, T., Di Sciascio, G., Feng, C. F., Feng, Z. Y., Gao, W., Gou, Q. B., Guo, Y. Q., He, H. H., Hu, Haibing, Hu, Hongbo, Iacovacci, M., Iuppa, R., Jia, H. Y., Labaciren, Null, Li, H. J., Liu, C., Liu, J., Liu, M. Y., Lu, H., Ma, L. L., Ma, X. H., Mancarella, G., Mari, S. M., Marsella, G., Mastroianni, S., Montini, P., Ning, C. C., Perrone, L., Pistilli, P., Ruffolo, D., Salvini, P., Santonico, R., Shen, P. R., Sheng, X. D., Shi, F., Surdo, A., Tan, Y. H., Vallania, P., Vernetto, S., Vigorito, C., Wang, H., Wu, C. Y., Wu, H. R., Xue, L., Yang, Q. Y., Yang, X. C., Yao, Z. G., Yuan, A. F., Zha, M., Zhang, H. M., Zhang, L., Zhang, X. Y., Zhang, Y., Zhao, J., Zhaxiciren, Null, Zhaxisangzhu, Null, Zhou, X. X., Zhu, F. R., Zhu, Q. Q., D'Amone, A., Piazzoli, B. D'Ettorre, Mastroianni, Stefano, Danzengluobu, null, Labaciren, null, Zhaxiciren, null, and Zhaxisangzhu, null
Subjects: Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Cosmic ray, 01 natural sciences, cosmic rays, 0103 physical sciences, Anisotropy, 010303 astronomy & astrophysics, Argo, cosmic ray, Astroparticle physics, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), 010308 nuclear & particles physics, Settore FIS/01 - Fisica Sperimentale, Northern Hemisphere, Astronomy, astroparticle physic, Astronomy and Astrophysics, astroparticle physics, cosmic ray anysotropy, argo-ybj, Astronomy and Astrophysic, astroparticle physics, Space and Planetary Science, 13. Climate action, Astrophysics - High Energy Astrophysical Phenomena
Abstract: This paper reports on the observation of the sidereal large-scale anisotropy of cosmic rays using data collected by the ARGO-YBJ experiment over 5 years (2008-2012). This analysis extends previous work limited to the period from 2008 January to 2009 December, near the minimum of solar activity between cycles 23 and 24. With the new data sample, the period of solar cycle 24 from near minimum to maximum is investigated. A new method is used to improve the energy reconstruction, allowing us to cover a much wider energy range, from 4 to 520 TeV. Below 100 TeV, the anisotropy is dominated by two wide regions, the so-called “tail-in” and “loss-cone” features. At higher energies, a dramatic change of the morphology is confirmed. The yearly time dependence of the anisotropy is investigated. Finally, no noticeable variation of cosmic-ray anisotropy with solar activity is observed for a median energy of 7 TeV.
Published: 2018
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41. Detection of thermal neutrons with the PRISMA-YBJ array in extensive air showers selected by the ARGO-YBJ experiment

Author: M. Zha, Labaciren, C. C. Ning, O. B. Shchegolev, L. Zhang, T. L. Chen, C. Vigorito, Z. Y. Cai, Zhenyong Feng, P. Bernardini, P. Salvini, Hm Zhang, C. Y. Wu, G. Marsella, C. Q. Liu, Q. B. Gou, V. Volchenko, L. L. Ma, P. Vallania, Zhengguo Cao, R. Santonico, H. H. He, H. Lu, G. Mancarella, H. Wang, Danzengluobu, J. K. K. Liu, B. D'Ettorre Piazzoli, A. D'Amone, Q. Q. Zhu, A. F. Yuan, F. Shi, X. W. Guo, S. M. Mari, P. R. Shen, X. C. Yang, X. X. Zhou, T. Di Girolamo, L. Xue, V. V. Alekseenko, Yu. V. Stenkin, Zhaxiciren, Y. H. Tan, Zhaxisangzhu, Hongbo Hu, V. Aynutdinov, Cunfeng Feng, S. W. Cui, V.I. Stepanov, Yicheng Guo, X. J. Bi, Ye Liu, S. Vernetto, Q. Y. Yang, S. Z. Chen, F. R. Zhu, S. Mastroianni, H. Y. Jia, H. J. Li, H. R. Wu, P. Montini, X. H. Ma, V. Rulev, Minghui Liu, A. Surdo, G. Di Sciascio, Zhaoyang Feng, X. Y. Zhang, Xiangdong Sheng, J. Zhao, S. Catalanotti, B. Z. Dai, Y. J. Zhang, R. Iuppa, B. Bartoli, I. De Mitri, Haibing Hu, Z. G. Yao, L. Perrone, P. Pistilli, H. M. Zhang, M. Iacovacci, Bartoli, B., Bernardini, P., Bi, X. J., Cao, Z., Catalanotti, S., Chen, S. Z., Chen, T. L., Cui, S. W., Dai, B. Z., D’Amone, A., Danzengluobu, Null, De Mitri, I., D’Ettorre Piazzoli, B., Di Girolamo, T., Di Sciascio, G., Feng, C. F., Feng, Zhaoyang, Feng, Zhenyong, Gou, Q. B., Guo, Y. Q., He, H. H., Hu, Haibing, Hu, Hongbo, Iacovacci, M., Iuppa, R., Jia, H. Y., Labaciren, Null, Li, H. J., Liu, C., Liu, J., Liu, M. Y., Lu, H., Ma, L. L., Ma, X. H., Mancarella, G., Mari, Stefano Maria, Marsella, G., Mastroianni, S., Montini, Paolo, Ning, C. C., Perrone, L., Pistilli, Pio, Salvini, P., Santonico, R., Shen, P. R., Sheng, X. D., Shi, F., Surdo, A., Tan, Y. H., Vallania, P., Vernetto, S., Vigorito, C., Wang, H., Wu, C. Y., Wu, H. R., Xue, L., Yang, Q. Y., Yang, X. C., Yao, Z. G., Yuan, A. F., Zha, M., Zhang, H. M., Zhang, L., Zhang, X. Y., Zhang, Y., Zhao, J., Zhaxiciren, Null, Zhaxisangzhu, Null, Zhou, X. X., Zhu, F. R., Zhu, Q. Q., Stenkin, Y. u. V., Alekseenko, V. V., Aynutdinov, V., Cai, Z. Y., Guo, X. W., Liu, Y., Rulev, V., Shchegolev, O. B., Stepanov, V., Volchenko, V., Zhang, H., Bartoli, B, Bernardini, Paolo, Bi, Xj, Cao, Z, Catalanotti, S, Chen, Sz, Chen, Tl, Cui, Sw, Dai, Bz, D'Amone, Antonio, Danzengluobu, DE MITRI, Ivan, Piazzoli, Bd, Di Girolamo, T, Di Sciascio, G, Feng, Cf, Feng, Zy, Gou, Qb, Guo, Yq, He, Hh, Hu, H, Iacovacci, M, Iuppa, R, Jia, Hy, Labaciren, Li, Hj, Liu, C, Liu, J, Liu, My, Lu, H, Ma, Ll, Ma, Xh, Mancarella, Giovanni, Mari, Sm, Marsella, Giovanni, Mastroianni, S, Montini, P, Ning, Cc, Perrone, Lorenzo, Pistilli, P, Salvini, P, Santonico, R, Shen, Pr, Sheng, Xd, Shi, F, Surdo, A, Tan, Yh, Vallania, P, Vernetto, S, Vigorito, C, Wang, H, Wu, Cy, Wu, Hr, Xue, L, Yang, Qy, Yang, Xc, Yao, Zg, Yuan, Af, Zha, M, Zhang, Hm, Zhang, L, Zhang, Xy, Zhang, Y, Zhao, J, Zhaxiciren, Zhaxisangzhu, Zhou, Xx, Zhu, Fr, Zhu, Qq, Stenkin, Yv, Alekseenko, Vv, Aynutdinov, V, Cai, Zy, Guo, Xw, Liu, Y, Rulev, V, Shchegolev, Ob, Stepanov, V, Volchenko, V, Zhang, H[ 7 ] . . . Less, Bartoli, Bruno, Catalanotti, Sergio, D'ETTORRE PIAZZOLI, Benedetto, DI GIROLAMO, Tristano, Iacovacci, Michele, Mari, S. M., Montini, P., and Pistilli, P.
Subjects: Physics - Instrumentation and Detectors, Astrophysics::High Energy Astrophysical Phenomena, Hadron, Extensive air shower, FOS: Physical sciences, Cosmic ray, 01 natural sciences, Nuclear physics, EN-detector, Hadronic component, RPC, Thermal neutron, Astronomy and Astrophysics, Observatory, Coincident, 0103 physical sciences, 010306 general physics, Cosmic-ray observatory, Instrumentation and Methods for Astrophysics (astro-ph.IM), High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Calorimeter (particle physics), 010308 nuclear & particles physics, Astrophysics::Instrumentation and Methods for Astrophysics, Instrumentation and Detectors (physics.ins-det), Neutron temperature, Air shower, High Energy Physics::Experiment, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract: We report on a measurement of thermal neutrons, generated by the hadronic component of extensive air showers (EAS), by means of a small array of EN-detectors developed for the PRISMA project (PRImary Spectrum Measurement Array), novel devices based on a compound alloy of ZnS(Ag) and $^{6}$LiF. This array has been operated within the ARGO-YBJ experiment at the high altitude Cosmic Ray Observatory in Yangbajing (Tibet, 4300 m a.s.l.). Due to the tight correlation between the air shower hadrons and thermal neutrons, this technique can be envisaged as a simple way to estimate the number of high energy hadrons in EAS. Coincident events generated by primary cosmic rays of energies greater than 100 TeV have been selected and analyzed. The EN-detectors have been used to record simultaneously thermal neutrons and the air shower electromagnetic component. The density distributions of both components and the total number of thermal neutrons have been measured. The correlation of these data with the measurements carried out by ARGO-YBJ confirms the excellent performance of the EN-detector., 35 pages, 16 figures
Published: 2016

42. STUDY OF THE DIFFUSE GAMMA-RAY EMISSION FROM THE GALACTIC PLANE WITH ARGO-YBJ

Author: Q. Q. Zhu, Labaciren, Zhengguo Cao, P. Bernardini, J. K. K. Liu, X. X. Zhou, C. Y. Wu, J. Zhao, Y. J. Zhang, R. Santonico, H. H. He, Zhenyong Feng, P. R. Shen, F. Shi, C. Q. Liu, Q. B. Gou, F. R. Zhu, P. Creti, C. C. Ning, X. C. Yang, Haifeng Li, H. Lu, I. De Mitri, A. D'Amone, P. Vallania, S. M. Mari, T. Di Girolamo, Danzengluobu, R. Cardarelli, A. F. Yuan, M. Panareo, Minghui Liu, B. D'Ettorre Piazzoli, Y. H. Tan, M. Zha, Lanqing Ma, X. J. Bi, L. Xue, L. Zhang, T. L. Chen, S. Vernetto, Zhaxiciren, A. Surdo, R. Iuppa, G. Zizzi, C. Vigorito, Zhaxisangzhu, P. Salvini, Q. Y. Yang, S. Z. Chen, G. Marsella, B. Bartoli, G. Liguori, M. Iacovacci, S. Catalanotti, B. Z. Dai, Zhaoyang Feng, Paolo Camarri, P. Montini, X. H. Ma, L. Perrone, G. Di Sciascio, X. Y. Zhang, A. Budano, Z. G. Yao, Haibing Hu, Xiangdong Sheng, S. Mastroianni, D. Martello, P. Pistilli, H. M. Zhang, H. R. Wu, Hongbo Hu, Yicheng Guo, H. Wang, Cunfeng Feng, F. Ruggieri, H. Y. Jia, S. W. Cui, G. Mancarella, P. Branchini, Mari, Stefano Maria, The ARGO YBJ, Collaboration, ITA, Bartoli, Bruno, Bernardini, P., Bi, X. J., Branchini, P., Budano, A., Camarri, P., Cao, Z., Cardarelli, R., Catalanotti, Sergio, Chen, S. Z., Chen, T. L., Creti, P., Cui, S. W., Dai, B. Z., D’Amone, A., Danzengluobu, Null, De Mitri, I., D'ETTORRE PIAZZOLI, Benedetto, DI GIROLAMO, Tristano, Sciascio, G. Di, Feng, C. F., Feng, Zhaoyang, Feng, Zhenyong, Gou, Q. B., Guo, Y. Q., He, H. H., Hu, Haibing, Hu, Hongbo, Iacovacci, Michele, Iuppa, R., Jia, H. Y., Labaciren, Null, Li, H. J., Liguori, G., Liu, C., Liu, J., Liu, M. Y., Lu, H., Ma, L. L., Ma, X. H., Mancarella, G., Mari, S. M., Marsella, G., Martello, D., Mastroianni, S., Montini, P., Ning, C. C., Panareo, M., Perrone, L., Pistilli, P., Ruggieri, F., Salvini, P., Santonico, R., Shen, P. R., Sheng, X. D., Shi, F., Surdo, A., Tan, Y. H., Vallania, P., Vernetto, S., Vigorito, C., Wang, H., Wu, C. Y., Wu, H. R., Xue, L., Yang, Q. Y., Yang, X. C., Yao, Z. G., Yuan, A. F., Zha, M., Zhang, H. M., Zhang, L., Zhang, X. Y., Zhang, Y., Zhao, J., Zhaxiciren, Null, Zhaxisangzhu, Null, Zhou, X. X., Zhu, F. R., Zhu, Q. Q., Zizzi, G., B., Bartoli, Bernardini, Paolo, X. J., Bi, P., Branchini, A., Budano, P., Camarri, Z., Cao, R., Cardarelli, S., Catalanotti, S. Z., Chen, T. L., Chen, P., Creti, S. W., Cui, B. Z., Dai, D'Amone, Antonio, Danzengluobu, DE MITRI, Ivan, B., D’Ettorre Piazzoli, T., Di Girolamo, G., Di Sciascio, C. F., Feng, Zhaoyang, Feng, Zhenyong, Feng, Q. B., Gou, Y. Q., Guo, H. H., He, Haibing, Hu, Hongbo, Hu, M., Iacovacci, R., Iuppa, H. Y., Jia, Labaciren, H. J., Li, G., Liguori, C., Liu, J., Liu, M. Y., Liu, H., Lu, L. L., Ma, X. H., Ma, Mancarella, Giovanni, S. M., Mari, Marsella, Giovanni, Martello, Daniele, S., Mastroianni, P., Montini, C. C., Ning, Panareo, Marco, Perrone, Lorenzo, P., Pistilli, F., Ruggieri, P., Salvini, R., Santonico, P. R., Shen, X. D., Sheng, F., Shi, A., Surdo, Y. H., Tan, P., Vallania, S., Vernetto, C., Vigorito, H., Wang, C. Y., Wu, H. R., Wu, L., Xue, Q. Y., Yang, X. C., Yang, Z. G., Yao, A. F., Yuan, M., Zha, H. M., Zhang, L., Zhang, X. Y., Zhang, Y., Zhang, J., Zhao, Zhaxiciren, Zhaxisangzhu, X. X., Zhou, F. R., Zhu, Q. Q., Zhu, and G., Zizzi
Subjects: Astrophysics::High Energy Astrophysical Phenomena, observational [methods], Flux, FOS: Physical sciences, Cosmic ray, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, disk, methods: observational [cosmic rays, diffuse radiation, Galaxy], Galaxy: disk, High Energy Physics - Phenomenology (hep-ph), cosmic rays, Disc, Instrumentation and Methods for Astrophysics (astro-ph.IM), cosmic ray, Astrophysics::Galaxy Astrophysics, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Settore FIS/01 - Fisica Sperimentale, Gamma ray, Astronomy and Astrophysics, Galactic plane, Galaxy, diffuse radiation, High Energy Physics - Phenomenology, Space and Planetary Science, Milagro, methods: observational, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, disk [Galaxy], Fermi Gamma-ray Space Telescope
Abstract: The events recorded by ARGO-YBJ in more than five years of data collection have been analyzed to determine the diffuse gamma-ray emission in the Galactic plane at Galactic longitudes 25{\deg} < l < 100{\deg} and Galactic latitudes . The energy range covered by this analysis, from ~350 GeV to ~2 TeV, allows the connection of the region explored by Fermi with the multi-TeV measurements carried out by Milagro. Our analysis has been focused on two selected regions of the Galactic plane, i.e., 40{\deg} < l < 100{\deg} and 65{\deg} < l < 85{\deg} (the Cygnus region), where Milagro observed an excess with respect to the predictions of current models. Great care has been taken in order to mask the most intense gamma-ray sources, including the TeV counterpart of the Cygnus cocoon recently identified by ARGO-YBJ, and to remove residual contributions. The ARGO-YBJ results do not show any excess at sub-TeV energies corresponding to the excess found by Milagro, and are consistent with the predictions of the Fermi model for the diffuse Galactic emission. From the measured energy distribution we derive spectral indices and the differential flux at 1 TeV of the diffuse gamma-ray emission in the sky regions investigated., Comment: 11 pages, 6 figures, published in APJ
Published: 2015

43. Observation of TeV gamma rays from the Cygnus region with the ARGO-YBJ experiment

Author: Carla Bleve, Q. Q. Zhu, B. S. Wang, Zhaxisangzhu, Hongbo Hu, C. F. Feng, B. Bartoli, Carlo Vigorito, S. M. Mari, A. F. Yuan, X. D. Sheng, Zhengguo Cao, Paolo Montini, T. Di Girolamo, G. Liguori, B. D'Ettorre Piazzoli, R. Iuppa, L. L. Ma, Haibing Hu, Jilong Zhang, Y. Q. Guo, E. Giroletti, Y. B. Chen, H. J. Li, Chang-Chun Ning, Zhaoyang Feng, H. R. Wu, F. Ruggieri, Y. Zhang, P. Bernardini, S. W. Cui, D. Martello, B. Panico, Labaciren, Jianli Zhang, L. Xue, M. Iacovacci, M. Zha, M. Y. Liu, P. R. Shen, X. Y. Zhang, B. Z. Dai, J. K. K. Liu, Antonio Budano, P. Pistilli, H. M. Zhang, X. X. Zhou, C. Cattaneo, H. Y. Jia, X. H. Ding, Hong-peng Lu, Q. Y. Yang, Zhaxiciren, P. Creti, A. K. Calabrese Melcarne, P. F. Zhang, Cristian Stanescu, P. Branchini, A. Surdo, Roberto Cardarelli, Danzengluobu, G. Zizzi, Q. Huang, X. J. Bi, G. Marsella, Zhenyong Feng, F. R. Zhu, S. Vernetto, C. Liu, Bingwei Xu, X. X. Li, S. Catalanotti, Paolo Camarri, Z. G. Yao, H.H. He, M. Dattoli, M. Panareo, Huaguang Wang, Y. H. Tan, X. H. Ma, Q. B. Gou, I. De Mitri, J. B. Zhao, P. Salvini, Fudong Shi, A. Pagliaro, S. Mastroianni, J. Y. Li, T. L. Chen, I. Bolognino, S. Z. Chen, Giovanni Mancarella, G. Di Sciascio, X. C. Yang, R. Santonico, Irina James, L. Perrone, F. Galeazzi, Longzhou Zhang, C. Y. Wu, C. Q. Liu, G. D'Alí Staiti, P. Vallania, B., Bartoli, Bernardini, Paolo, X. J., Bi, C., Bleve, I., Bolognino, P., Branchini, A., Budano, A. K., Calabrese Melcarne, P., Camarri, Z., Cao, R., Cardarelli, S., Catalanotti, C., Cattaneo, S. Z., Chen, T. L., Chen, Y., Chen, P., Creti, S. W., Cui, B. Z., Dai, G., D'Alí Staiti, Danzengluobu, M., Dattoli, DE MITRI, Ivan, B., D'Ettorre Piazzoli, T., Di Girolamo, X. H., Ding, G., Di Sciascio, C. F., Feng, Zhaoyang, Feng, Zhenyong, Feng, F., Galeazzi, E., Giroletti, Q. B., Gou, Y. Q., Guo, H. H., He, Haibing, Hu, Hongbo, Hu, Q., Huang, M., Iacovacci, R., Iuppa, I., Jame, H. Y., Jia, Labaciren, H. J., Li, J. Y., Li, X. X., Li, G., Liguori, C., Liu, C. Q., Liu, J., Liu, M. Y., Liu, H., Lu, L. L., Ma, X. H., Ma, Mancarella, Giovanni, S. M., Mari, Marsella, Giovanni, Martello, Daniele, S., Mastroianni, P., Montini, C. C., Ning, A., Pagliaro, Panareo, Marco, B., Panico, Perrone, Lorenzo, P., Pistilli, F., Ruggieri, P., Salvini, R., Santonico, P. R., Shen, X. D., Sheng, F., Shi, C., Stanescu, A., Surdo, Y. H., Tan, P., Vallania, S., Vernetto, C., Vigorito, B., Wang, H., Wang, C. Y., Wu, H. R., Wu, B., Xu, L., Xue, Q. Y., Yang, X. C., Yang, Z. G., Yao, A. F., Yuan, M., Zha, H. M., Zhang, Jilong, Zhang, Jianli, Zhang, L., Zhang, P., Zhang, X. Y., Zhang, Y., Zhang, J., Zhao, Zhaxiciren, Zhaxisangzhu, X. X., Zhou, F. R., Zhu, Q. Q., Zhu, G., Zizzi, Bartoli, Bruno, Bernardini, P., Bleve, C., Bolognino, I., Branchini, P., Budano, A., A. K. C., Camarri, P., Cao, Z., Cardarelli, R., Catalanotti, Sergio, Cattaneo, C., Chen, S. Z., Chen, T. L., Chen, Y., Creti, P., Cui, S. W., Dai, B. Z., Staiti, G. D., Dattoli, M., Mitri, I. D., D'ETTORRE PIAZZOLI, Benedetto, DI GIROLAMO, Tristano, Ding, X. H., Sciascio, G. D., Feng, C. F., Feng, Z. Y., Galeazzi, F., Giroletti, E., Gou, Q. B., Guo, Y. Q., H. B., Hu, Huang, Q., Iacovacci, Michele, Iuppa, R., James, I., Jia, H. Y., Liguori, G., Liu, C., Liu, C. Q., Liu, J., Liu, M. Y., Lu, H., Mancarella, G., Mari, S. M., Marsella, G., Martello, D., Mastroianni, S., Montini, P., Ning, C. C., Pagliaro, A., Panareo, M., Panico, B., Perrone, L., Pistilli, P., Ruggieri, F., Salvini, P., Santonico, R., Shen, P. R., Sheng, X. D., Shi, F., Stanescu, C., Surdo, A., Tan, Y. H., Vallania, P., Vernetto, S., Vigorito, C., Wang, B., Wang, H., Xu, B., Xue, L., Yang, Q. Y., Yang, X. C., Yao, Z. G., Yuan, A. F., Zha, M., Zhang, H. M., Zhang, J. L., Zhang, L., Zhang, P., Zhang, X. Y., Zhang, Y., Zhao, J., Zhou, X. X., Zhu, F. R., Zhu, Q. Q., Zizzi, G., Bartoli, B, Bernardini, P, Bi, XJ, Bleve, C, Bolognino, I, Branchini, P, Budano, A, Calabrese Melcarne, AK, Camarri, P, Cao, Z, Cardarelli, R, Catalanotti, S, Cattaneo, C, Chen, SZ, Chen, TL, Chen, Y, Creti, P, Cui, SW, Dai, BZ, D’Ali Staiti, G, Dattoli, M, De Mitri, I, D’Ettorre Piazzoli, B, Di Girolamo, T, Ding, XH, Di Sciascio, G, Feng, CF, Feng, ZYa, Feng, ZYo, Galeazzi, F, Giroletti, E, Gou, QB, Guo, YQ, He, HH, Hu, HBi, Hu, HBo, Huang, Q, Iacovacci, M, Iuppa, R, James, I, Jia, HY, Li, HJ, Li, JY, Li, XX, Liguori, G, Liu, C, Liu, CQ, Liu, J, Liu, MY, Lu, H, Ma, LL, Ma, XH, Mancarella, G, Mari, SM, Marsella, G, Martello, D, Mastroianni, S, Montini, P, Ning, CC, Pagliaro, A, Panareo, M, Panico, B, Perrone, L, Pistilli, P, Ruggieri, F, Salvini, P, Santonico, R, Shen, PR, Sheng, XD, Shi, F, Stanescu, C, Surdo, A, Tan, YH, Vallania, P, Vernetto, S, Vigorito, C, Wang, B, Wang, H, Wu, CY, Wu, HR, Xu, B, Xue, L, Yang, QY, Yang, XC, Yao, ZG, Yuan, AF, M. Zha, M, Zhang, HM, Zhang, JLi, Zhang, JLo, Zhang, L, Zhang, P, Zhang, XY, Zhang, Y, Zhao, J, Zhaxiciren, Zhaxisangzhu, Zhou, XX, Zhu, FR, Zhu, QQ, Zizzi, G, Bartoli, B., Bi, X. J., Melcarne A. K., Calabrese, Catalanotti, S., Staiti G., D'Ali, De Mitri, I., Piazzoli B., D'Ettorre, Di Girolamo, T., Di Sciascio, G., Feng, Zhaoyang, Feng, Zhenyong, He, H. H., Hu, Haibing, Hu, Hongbo, Iacovacci, M., Li, H. J., Li, J. Y., Li, X. X., Ma, L. L., Ma, X. H., Mari, Stefano Maria, Wu, C. Y., Wu, H. R., Zhang, Jilong, and Zhang, Jianli
Subjects: Astrophysics::High Energy Astrophysical Phenomena, general – pulsars: individual (MGRO J2019+37 [Gamma rays], Flux, FOS: Physical sciences, Astrophysics, 01 natural sciences, Pulsar wind nebula, general – pulsar, 0103 physical sciences, MILAGRO, 010303 astronomy & astrophysics, DETECTOR, Argo, Physics, CALIBRATION, High Energy Astrophysical Phenomena (astro-ph.HE), 010308 nuclear & particles physics, MGRO J2031+41), Settore FIS/01 - Fisica Sperimentale, Gamma ray, Astronomy and Astrophysics, individual (MGRO J2019+37, MGRO J2031+41), PLANE, 3. Good health, Medium energy, Crab Nebula, gamma ray, 13. Climate action, Space and Planetary Science, GALACTIC SOURCES, J2032+4130, Milagro, gamma rays, general – pulsars, EMISSION, Astrophysics - High Energy Astrophysical Phenomena
Abstract: We report the observation of TeV gamma-rays from the Cygnus region using the ARGO-YBJ data collected from 2007 November to 2011 August. Several TeV sources are located in this region including the two bright extended MGRO J2019+37 and MGRO J2031+41. According to the Milagro data set, at 20 TeV MGRO J2019+37 is the most significant source apart from the Crab Nebula. No signal from MGRO J2019+37 is detected by the ARGO-YBJ experiment, and the derived flux upper limits at 90% confidence level for all the events above 600 GeV with medium energy of 3 TeV are lower than the Milagro flux, implying that the source might be variable and hard to be identified as a pulsar wind nebula. The only statistically significant (6.4 standard deviations) gamma-ray signal is found from MGRO J2031+41, with a flux consistent with the measurement by Milagro., 14 pages, 4 figures
Published: 2012

44. Measurement of the cosmic ray antiproton/proton flux ratio at TeV energies with the ARGO-YBJ detector

Author: X. X. Li, I. De Mitri, M. Iacovacci, M. Zha, G. D'Alí Staiti, Zhenyong Feng, P. Vallania, S. Vernetto, C. Cattaneo, F. R. Zhu, C. Liu, T. L. Chen, X. H. Ma, H.H. He, S. W. Cui, Jilong Zhang, F. Ruggieri, Q. Q. Zhu, P. Bernardini, S. Catalanotti, M. Panareo, Giovanni Mancarella, T. Di Girolamo, B. D'Ettorre Piazzoli, Y. Q. Guo, Carla Bleve, C. Y. Wu, E. Giroletti, B. Panico, P. Salvini, Zhaxiciren, R. Santonico, Zihuang Cao, Y. B. Chen, H. J. Li, Paolo Camarri, C. Q. Liu, H. R. Wu, Hongbo Hu, L. Xue, C. F. Feng, A. K. Calabrese Melcarne, A. F. Yuan, Carlo Vigorito, B. Z. Dai, Paolo Montini, R. Iuppa, B. Bartoli, Hong-peng Lu, X. Y. Zhang, X. C. Yang, G. Marsella, Haibing Hu, Cristian Stanescu, P. Branchini, Y. X. Yan, Antonio Budano, B. S. Wang, J. K. K. Liu, Zhaxisangzhu, Labaciren, Irina James, Y. Zhang, Chang-Chun Ning, Zhaoyang Feng, D. Martello, Longzhou Zhang, L. Perrone, Jianli Zhang, P. Creti, P. Pistilli, H. M. Zhang, X. X. Zhou, Z. G. Yao, Bingwei Xu, A. Surdo, Q. Huang, Huaguang Wang, G. Liguori, Fudong Shi, S. Mastroianni, Q. B. Gou, X. D. Sheng, P. R. Shen, P. F. Zhang, X. J. Bi, S. Z. Chen, S. M. Mari, X. B. Qu, X. H. Ding, Roberto Cardarelli, G. Di Sciascio, Y. H. Tan, J. Y. Li, M. Y. Liu, Q. Y. Yang, H. Y. Jia, Danzengluobu, G. Zizzi, I. Bolognino, A. Pagliaro, Bartoli, B., Bernardini, P., Bi, X. J., Bleve, C., Bolognino, I., Branchini, P., Budano, A., Melcarne A. K., Calabrese, Camarri, P., Cao, Z., Cardarelli, R., Catalanotti, S., Cattaneo, C., Chen, S. Z., Chen, T. L., Chen, Y., Creti, P., Cui, S. W., Dai, B. Z., Staiti G., D'Ali, Danzengluobu, De Mitri, I., Piazzoli B., D'Ettorre, Di Girolamo, T., Ding, X. H., Di Sciascio, G., Feng, C. F., Feng, Zhaoyang, Feng, Zhenyong, Giroletti, E., Gou, Q. B., Guo, Y. Q., He, H. H., Hu, Haibing, Hu, Hongbo, Huang, Q., Iacovacci, M., Iuppa, R., James, I., Jia, H. Y., Labaciren, Li, H. J., Li, J. Y., Li, X. X., Liguori, G., Liu, C., Liu, C. Q., Liu, J., Liu, M. Y., Lu, H., Ma, X. H., Mancarella, G., Mari, Stefano Maria, Marsella, G., Martello, D., Mastroianni, S., Montini, P., Ning, C. C., Pagliaro, A., Panareo, M., Panico, B., Perrone, L., Pistilli, P., Qu, X. B., Ruggieri, F., Salvini, P., Santonico, R., Shen, P. R., Sheng, X. D., Shi, F., Stanescu, C., Surdo, A., Tan, Y. H., Vallania, P., Vernetto, S., Vigorito, C., Wang, B., Wang, H., Wu, C. Y., Wu, H. R., Xu, B., Xue, L., Yan, Y. X., Yang, Q. Y., Yang, X. C., Yao, Z. G., Yuan, A. F., Zha, M., Zhang, H. M., Zhang, Jilong, Zhang, Jianli, Zhang, L., Zhang, P., Zhang, X. Y., Zhang, Y., Zhaxiciren, Zhaxisangzhu, Zhou, X. X., Zhu, F. R., Zhu, Q. Q., Zizzi, G., Bartoli, Bruno, Bi, X., Calabrese Melcarne, A., Catalanotti, Sergio, Chen, S., Chen, T., Cui, S., Dai, B., D’Alí Staiti, G., D'ETTORRE PIAZZOLI, Benedetto, DI GIROLAMO, Tristano, Ding, X., Feng, C., Zhaoyang, Feng, Zhenyong, Feng, Gou, Q., Guo, Y., He, H., Haibing, Hu, Hongbo, Hu, Iacovacci, Michele, Jia, H., Li, H., Li, J., Li, X., Liu, M., Ma, X., Mari, S., Ning, C., Qu, X., Shen, P., Sheng, X., Tan, Y., Wu, C., Wu, H., Yan, Y., Yang, Q., Yang, X., Yao, Z., Yuan, A., Zhang, H., Jilong, Zhang, Jianli, Zhang, Zhang, X., Zhou, X., Zhu, F., Zhu, Q., Bartoli, B, Bernardini, P, Bi, XJ, Bleve, C, Bolognino, I, Branchini, P, Budano, A, Calabrese Melcarne, AK, Camarri, P, Cao, Z, Cardarelli, R, Catalanotti, S, Cattaneo, C, Chen, SZ, Chen, TL, Chen, Y, Creti, P, Cui, SW, Dai, BZ, D’Ali' Staiti, G, De Mitri, I, D’Ettorre Piazzoli, B, Di Girolamo, T, Ding, XH, Di Sciascio, G, Feng, CF, Feng, ZYa, Feng, ZYo, Giroletti, E, Gou, QB, Guo, YQ, He, HH, Hu, HBa, Hu, HBo, Huang, Q, Iacovacci, M, Iuppa, R, James, I, Jia, HY, Li, HJ, Li, JY, Li, XX, Liguori, G, Liu, C, Liu, CQ, Liu, J, Liu, MY, Lu, H, Ma, XH, Mancarella, G, Mari, SM, Marsella, G, Martello, D, Mastroianni, S, Montini, P, Ning, CC, Pagliaro, A, Panareo, M, Panico, B, Perrone, L, Pistilli, P, Qu, XB, Ruggieri, F, Salvini, P, Santonico, R, Shen, PR, Sheng, XD, Shi, F, Stanescu, C, Surdo, A, Tan, YH, Vallania, P, Vernetto, S, Vigorito, C, Wang, B, Wang, H, Wu, CY, Wu, HR, Xu B, Xue, L, Yan, YX, Yang, QY, Yang, XC, Yao, ZG, Yuan, AF, Zha, M, Zhang, HM, Zhang, JLo, Zhang, JLi, Zhang, L, Zhang, P, Zhang, XY, Zhang, Y, Zhaxiciren, Zhaxisangzhu, Zhou, XX, Zhu, FR, Zhu, QQ, Zizzi, G, B., Bartoli, Bernardini, Paolo, X. J., Bi, C., Bleve, I., Bolognino, P., Branchini, A., Budano, A. K., Calabrese Melcarne, P., Camarri, Z., Cao, R., Cardarelli, S., Catalanotti, C., Cattaneo, S. Z., Chen, T. L., Chen, Y., Chen, P., Creti, S. W., Cui, B. Z., Dai, G., D’Alí Staiti, DE MITRI, Ivan, B., D’Ettorre Piazzoli, T., Di Girolamo, X. H., Ding, G., Di Sciascio, C. F., Feng, E., Giroletti, Q. B., Gou, Y. Q., Guo, H. H., He, Q., Huang, M., Iacovacci, R., Iuppa, I., Jame, H. Y., Jia, H. J., Li, J. Y., Li, X. X., Li, G., Liguori, C., Liu, C. Q., Liu, J., Liu, M. Y., Liu, H., Lu, X. H., Ma, Mancarella, Giovanni, S. M., Mari, Marsella, Giovanni, Martello, Daniele, S., Mastroianni, P., Montini, C. C., Ning, A., Pagliaro, Panareo, Marco, B., Panico, Perrone, Lorenzo, P., Pistilli, X. B., Qu, F., Ruggieri, P., Salvini, R., Santonico, P. R., Shen, X. D., Sheng, F., Shi, C., Stanescu, A., Surdo, Y. H., Tan, P., Vallania, S., Vernetto, C., Vigorito, B., Wang, H., Wang, C. Y., Wu, H. R., Wu, B., Xu, L., Xue, Y. X., Yan, Q. Y., Yang, X. C., Yang, Z. G., Yao, A. F., Yuan, M., Zha, H. M., Zhang, L., Zhang, P., Zhang, X. Y., Zhang, Y., Zhang, X. X., Zhou, F. R., Zhu, Q. Q., Zhu, and G., Zizzi
Subjects: Physics, Nuclear and High Energy Physics, Antiparticle, Astrophysics::High Energy Astrophysical Phenomena, Dark matter, Settore FIS/01 - Fisica Sperimentale, Earth-Moon, Cosmic ray, magnetic spectrometer, High Energy Physics - Experiment, Nuclear physics, Earth's magnetic field, Antiproton, Antimatter, antiproton, Content (measure theory), Antiproton-Proton ratio, Cosmic rays, Extended Air Showers, Astrophysics - High Energy Astrophysical Phenomena, Energy (signal processing)
Abstract: Cosmic ray antiprotons provide an important probe to study the cosmic ray propagation in the interstellar space and to investigate the existence of dark matter. Acting the Earth-Moon system as a magnetic spectrometer, paths of primary antiprotons are deflected in the opposite sense with respect to those of the protons in their way to the Earth. This effect allows, in principle, the search for antiparticles in the direction opposite to the observed deficit of cosmic rays due to the Moon (the so-called `Moon shadow'). The ARGO-YBJ experiment, located at the Yangbajing Cosmic Ray Laboratory (Tibet, P.R. China, 4300 m a.s.l., 606 g/cm$^2$), is particularly effective in measuring the cosmic ray antimatter content via the observation of the cosmic rays shadowing effect due to: (1) good angular resolution, pointing accuracy and long-term stability; (2) low energy threshold; (3) real sensitivity to the geomagnetic field. Based on all the data recorded during the period from July 2006 through November 2009 and on a full Monte Carlo simulation, we searched for the existence of the shadow cast by antiprotons in the TeV energy region. No evidence of the existence of antiprotons is found in this energy region. Upper limits to the $\bar{p}/p$ flux ratio are set to 5 % at a median energy of 1.4 TeV and 6 % at 5 TeV with a confidence level of 90%. In the TeV energy range these limits are the lowest available., Comment: Contact authors: G. Di Sciascio (disciascio@roma2.infn.it) and R. Iuppa (iuppa@roma2.infn.it), INFN Sezione di Roma Tor Vergata, Roma, Italy
Published: 2012

45. ARGO-YBJ OBSERVATION OF THE LARGE-SCALE COSMIC RAY ANISOTROPY DURING THE SOLAR MINIMUM BETWEEN CYCLES 23 AND 24

Author: Lanqing Ma, M. Iacovacci, M. Zha, S. W. Cui, H. W. Wang, X. D. Sheng, G. Mancarella, Q. Y. Yang, B. D'Ettorre Piazzoli, Paolo Bernardini, Zhaxisangzhu, X. J. Bi, B. Bartoli, X. C. Yang, R. Santonico, L. Zhang, S. Z. Chen, C. Y. Wu, A. F. Yuan, Zhaxiciren, J. W. Zhao, Haibing Hu, F. R. Zhu, P. Salvini, W. Gao, A. D'Amone, L. Xue, Labaciren, G. Marsella, L. Perrone, Fudong Shi, Q. Q. Zhu, Danzengluobu, S. Mastroianni, Hong-peng Lu, Y. Zhang, I. De Mitri, C. X. Liu, J. K. K. Liu, Z. G. Yao, T. L. Chen, Zihuang Cao, Zhenyong Feng, S. M. Mari, Y. H. Tan, H. H. He, Carlo Vigorito, P. Pistilli, H. M. Zhang, X. X. Zhou, H. Y. Jia, G. Di Sciascio, X. Y. Zhang, Minghui Liu, B. Z. Dai, P. Montini, X. H. Ma, Y. Q. Guo, Piero Vallania, H. J. Li, H. R. Wu, Hongbo Hu, A. Surdo, C. F. Feng, Q. B. Gou, T. Di Girolamo, R. Iuppa, S. Vernetto, Pengnian Shen, S. Catalanotti, Chang-Chun Ning, Zhaoyang Feng, Bartoli, Bruno, Bernardini, P., Bi, X. J., Cao, Z., Catalanotti, Sergio, Chen, S. Z., Chen, T. L., Cui, S. W., Dai, B. Z., D’Amone, A., Danzengluobu, Null, D’Ettorre Piazzoli, B., DI GIROLAMO, Tristano, Sciascio, G. Di, Feng, C. F., Feng, Zhaoyang, Feng, Zhenyong, Gao, W., Gou, Q. B., Guo, Y. Q., He, H. H., Hu, Haibing, Hu, Hongbo, Iacovacci, Michele, Iuppa, R., Jia, H. Y., Labaciren, Null, Li, H. J., Liu, C., Liu, J., Liu, M. Y., Lu, H., Ma, L. L., Ma, X. H., Mancarella, G., Mari, S. M., Marsella, G., Mastroianni, S., Montini, P., Ning, C. C., Perrone, L., Pistilli, P., Salvini, P., Santonico, R., Shen, P. R., Sheng, X. D., Shi, F., Surdo, A., Tan, Y. H., Vallania, P., Vernetto, S., Vigorito, C., Wang, H., Wu, C. Y., Wu, H. R., Xue, L., Yang, Q. Y., Yang, X. C., Yao, Z. G., Yuan, A. F., Zha, M., Zhang, H. M., Zhang, L., Zhang, X. Y., Zhang, Y., Zhao, J., Zhaxiciren, Null, Zhaxisangzhu, Null, Zhou, X. X., Zhu, F. R., Zhu, Q. Q., Bartoli, B., Catalanotti, S., D'Amone, A., Danzengluobu, Mitri, I. D., Piazzoli, B. D., Girolamo, T. D., Sciascio, G. D., Feng, Z., Hu, H., Iacovacci, M., Labaciren, Zhaxiciren, Zhaxisangzhu, ITA, Mitri, I. De, Piazzoli, B. D'Ettorre, and Girolamo, T. Di
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Solar minimum, Physics, cosmic rays, methods: data analysis, methods: observational, Astronomy and Astrophysics, Space and Planetary Science, Astrophysics::High Energy Astrophysical Phenomena, observational [methods], Phase (waves), FOS: Physical sciences, Flux, Cosmic ray, Astrophysics, Astronomy and Astrophysic, Amplitude, Air shower, data analysi [methods], Astrophysics - High Energy Astrophysical Phenomena, Anisotropy, Event (particle physics), cosmic ray
Abstract: This paper reports on the measurement of the large-scale anisotropy in the distribution of cosmic-ray arrival directions using the data collected by the air shower detector ARGO-YBJ from 2008 January to 2009 December,during the minimum of solar activity between cycles 23 and 24. In this period, more than 200 billion showers were recorded with energies between 1 and 30 TeV. The observed two-dimensional distribution of cosmic rays is characterized by two wide regions of excess and deficit, respectively, both of relative intensity 0.001 with respect to a uniform flux, superimposed on smaller size structures. The harmonic analysis shows that the large-scale cosmic-ray relative intensity as a function of R.A. can be described by the first and second terms of a Fouries series. The high event statistics allow the study of the energy dependence of the anistropy, showing that the amplitude increases with energy, with a maximum intensity at 10 TeV, and then decreases while the phase slowly shifts toward lower values of R.A. with increasing energy. The ARGO-YBJ data provide accurate observations over more than a decade of energy around this feature of the anisotropy spectrum., Comment: 9pages, 6figures
Published: 2015
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46. CRAB NEBULA: FIVE-YEAR OBSERVATION WITH ARGO-YBJ

Author: X. C. Yang, B. Bartoli, R. Cardarelli, X. Y. Zhang, G. Marsella, B. D'Ettorre Piazzoli, Minghui Liu, Zhenyong Feng, H. H. He, C. Y. Wu, L. Xue, Q. B. Gou, Q. Y. Yang, M. Iacovacci, M. Zha, G. Zizzi, P. Salvini, L. Perrone, X. D. Sheng, Paolo Bernardini, J. W. Zhao, H. R. Wu, Piero Vallania, P. Creti, H. Y. Jia, Paolo Camarri, I. De Mitri, Zihuang Cao, L. Zhang, T. L. Chen, Haifeng Li, Cunfeng Feng, M. Panareo, S. M. Mari, B. Z. Dai, Pengnian Shen, Lanqing Ma, Z. G. Yao, F. Ruggieri, Danzengluobu, S. Catalanotti, Hongbo Hu, A. Surdo, Yicheng Guo, A. Budano, Y. H. Tan, S. W. Cui, R. Santonico, X. J. Bi, Fudong Shi, Chang-Chun Ning, X. H. Ma, H. Lu, P. Branchini, Zhaoyang Feng, G. Liguori, S. Z. Chen, S. Mastroianni, G. Mancarella, Paolo Montini, F. R. Zhu, R. Iuppa, C. X. Liu, S. Vernetto, G. Di Sciascio, E. Striani, Q. Q. Zhu, H. W. Wang, A. D'Amone, J. K. K. Liu, Zhaxiciren, Labaciren, A. F. Yuan, P. Pistilli, H. M. Zhang, X. X. Zhou, Haibing Hu, Y. Zhang, D. Martello, Carlo Vigorito, T. Di Girolamo, Zhaxisangzhu, ITA, Bartoli, B., Bernardini, P., Bi, X. J., Branchini, P., Budano, A., Camarri, P., Cao, Z., Cardarelli, R., Catalanotti, S., Chen, S. Z., Chen, T. L., Creti, P., Cui, S. W., Dai, B. Z., D'Amone, A., Danzengluobu, De Mitri, I., D'Ettorre Piazzoli, B., Di Girolamo, T., Di Sciascio, G., Feng, C. F., Feng, Zhaoyang, Feng, Zhenyong, Gou, Q. B., Guo, Y. Q., He, H. H., Hu, Haibing, Hu, Hongbo, Iacovacci, M., Iuppa, R., Jia, H. Y., Labaciren, Li, H. J., Liguori, G., Liu, C., Liu, J., Liu, M. Y., Lu, H., Ma, L. L., Ma, X. H., Mancarella, G., Mari, S. M., Marsella, G., Martello, D., Mastroianni, S., Montini, P., Ning, C. C., Panareo, M., Perrone, L., Pistilli, P., Ruggieri, F., Salvini, P., Santonico, R., Shen, P. R., Sheng, X. D., Shi, F., Surdo, A., Tan, Y. H., Vallania, P., Vernetto, S., Vigorito, C., Wang, H., Wu, C. Y., Wu, H. R., Xue, L., Yang, Q. Y., Yang, X. C., Yao, Z. G., Yuan, A. F., Zha, M., Zhang, H. M., Zhang, L., Zhang, X. Y., Zhang, Y., Zhao, J., Zhaxisangzhu, Zhaxiciren, Zhou, X. X., Zhu, F. R., Zhu, Q. Q., Zizzi, G., Striani, E., B., Bartoli, Bernardini, Paolo, X. J., Bi, P., Branchini, A., Budano, P., Camarri, Z., Cao, R., Cardarelli, S., Catalanotti, S. Z., Chen, T. L., Chen, P., Creti, S. W., Cui, B. Z., Dai, D'Amone, Antonio, DE MITRI, Ivan, B., D'Ettorre Piazzoli, T., Di Girolamo, G., Di Sciascio, C. F., Feng, Zhaoyang, Feng, Zhenyong, Feng, Q. B., Gou, Y. Q., Guo, H. H., He, Haibing, Hu, Hongbo, Hu, M., Iacovacci, R., Iuppa, H. Y., Jia, H. J., Li, G., Liguori, C., Liu, J., Liu, M. Y., Liu, H., Lu, L. L., Ma, X. H., Ma, Mancarella, Giovanni, S. M., Mari, Marsella, Giovanni, Martello, Daniele, S., Mastroianni, P., Montini, C. C., Ning, Panareo, Marco, Perrone, Lorenzo, P., Pistilli, F., Ruggieri, P., Salvini, R., Santonico, P. R., Shen, X. D., Sheng, F., Shi, A., Surdo, Y. H., Tan, P., Vallania, S., Vernetto, C., Vigorito, H., Wang, C. Y., Wu, H. R., Wu, L., Xue, Q. Y., Yang, X. C., Yang, Z. G., Yao, A. F., Yuan, M., Zha, H. M., Zhang, L., Zhang, X. Y., Zhang, Y., Zhang, J., Zhao, Zhaxiciren, Zhaxisangzhu, X. X., Zhou, F. R., Zhu, Q. Q., Zhu, G., Zizzi, E., Striani, Bartoli, Bruno, Catalanotti, Sergio, Danzengluobu, Null, D'ETTORRE PIAZZOLI, Benedetto, DI GIROLAMO, Tristano, Iacovacci, Michele, Labaciren, Null, Zhaxiciren, Null, and Zhaxisangzhu, Null
Subjects: Physics, Spectral index, Astrophysics::High Energy Astrophysical Phenomena, Settore FIS/01 - Fisica Sperimentale, individual (Crab Nebula) [pulsars], Flux, Astronomy and Astrophysics, Astrophysics, Light curve, Power law, star [gamma rays], Air shower, Crab Nebula, Pulsar, Space and Planetary Science, Cutoff, High Energy Physics::Experiment, Astrophysics - High Energy Astrophysical Phenomena
Abstract: The ARGO-YBJ air shower detector monitored the Crab Nebula gamma ray emission from 2007 November to 2013 February. The integrated signal, consisting of $\sim$3.3 $\times$ 10$^5$ events,reached the statistical significance of 21.1 standard deviations. The obtained energy spectrum in the energy range 0.3-20 TeV can be described by a power law function dN/dE = I$_0$ (E / 2 TeV)$^{-\alpha}$, with a flux normalization I$_0$ = (5.2 $\pm$ 0.2) $\times$ 10$^{-12}$ photons cm$^{-2}$ s$^{-1}$ TeV$^{-1}$ and $\alpha$ = 2.63 $\pm$ 0.05, corresponding to an integrated flux above 1 TeV of 1.97 $\times$ 10$^{-11}$ photons cm$^{-2}$ s$^{-1}$. The systematic error is estimated to be less than 30$\%$ for the flux normalization and 0.06 for the spectral index. Assuming a power law spectrum with an exponential cutoff dN/dE = I$_0$ (E / 2 TeV)$^{-\alpha}$ $\exp$ (-E / E$_{cut}$), the lower limit of the cutoff energy E$_{cut}$ is 12 TeV, at 90$\%$ confidence level. Our extended dataset allows the study of the TeV emission over long timescales. Over five years, the light curve of the Crab Nebula in 200-day bins is compatible with a steady emission with a probability of 7.3 $\times$ 10$^{-2}$. A correlated analysis with Fermi-LAT data over $\sim$4.5 years using the light curves of the two experiments gives a Pearson correlation coefficient $r$ = 0.56 $\pm$ 0.22. Concerning flux variations on timescales of days, a "blind" search for flares with a duration of 1-15 days gives no excess with a significance higher than four standard deviations. The average rate measured by ARGO-YBJ during the three most powerful flares detected by Fermi-LAT is 205 $\pm$ 91 photons day$^{-1}$, consistent with the average value of 137 $\pm$ 10 day$^{-1}$., Comment: 12 pages, 10 figures
Published: 2015
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