Measurement of the Cosmic Ray Helium Energy Spectrum from 70 GeV to 80 TeV with the DAMPE Space Mission
Francesco Alemanno, Q. An, P. Azzarello, Felicia Barbato, P. Bernardini, Xiao-Jun Bi, Mingsheng Cai, E. Catanzani, Jin Chang, D. Y. Chen, J. L. Chen, Z. F. Chen, Maxwell Cui, T. S. Cui, Yuxin Cui, Haoting Dai, A. D׳Amone, A. De Benedittis, I. De Mitri, F. de Palma, M. Deliyergiyev, Margherita Di Santo, Ting Dong, Z. X. Dong, Giacinto Donvito, David Droz, Jinglai Duan, K. K. Duan, D. D’Urso, Ruirui Fan, Y. Z. Fan, Ke Fang, F. Fang, C. Q. Feng, Lei Feng, P. Fusco, M. Gao, F. Gargano, Ke Gong, Yuanlin Gong, D. Y. Guo, Jian‐Hua Guo, Xudong Guo, Shuo Han, Yi-Ming Hu, G. S. Huang, Xiaoyuan Huang, Y. Huang, M. Ionica, Wei Jiang, Jie Kong, Andrii Kotenko, Dimitrios Kyratzis, S. J. Lei, Shangrong Li, W. L. Li, X Li, Xuanle Li, Yan Liang, C. M. Liu, H. Liu, Jiangying Liu, S. B. Liu, Wei Liu, Ye Liu, F. Loparco, C. N. Luo, M. Ma, Peng-Xiong Ma, T. Ma, X. Y., G. Marsella, M. N. Mazziotta, D. Mo, X. Y. Niu, X. Pan, A. Parenti, Wen-Xi Peng, X. Y. Peng, C. Perrina, Rui Qiao, J. N. Rao, Arshia Ruina, M. M. Salinas, Guojin Shang, W. H. Shen, Zhao-Qiang Shen, Z. T. Shen, Leandro Silveri, J. X. Song, M. Stolpovskiy, H. Su, Meng Su, Ze-Tong Sun, A. Surdo, Xueyi Teng, A. Tykhonov, H. Wang, Junfeng Wang, L. G. Wang
Abstract
The measurement of the energy spectrum of cosmic ray helium nuclei from 70 GeV to 80 TeV using 4.5 years of data recorded by the Dark Matter Particle Explorer (DAMPE) is reported in this work. A hardening of the spectrum is observed at an energy of about 1.3 TeV, similar to previous observations. In addition, a spectral softening at about 34 TeV is revealed for the first time with large statistics and well controlled systematic uncertainties, with an overall significance of 4.3σ. The DAMPE spectral measurements of both cosmic protons and helium nuclei suggest a particle charge dependent softening energy, although with current uncertainties a dependence on the number of nucleons cannot be ruled out.