Observation of a Spectral Hardening in Cosmic Ray Boron Spectrum with the DAMPE Space Mission
F. Alemanno, C. Altomare, Qi An, P. Azzarello, F. C. T. Barbato, P. Bernardini, X. J. Bi, Henri Boutin, I. Cagnoli, M. S. Cai, E. Casilli, E. Catanzani, Jin Chang, D. Y. Chen, Ji‐Long Chen, Z. F. Chen, Z. X. Chen, Paul Coppin, Maxwell Cui, T. S. Cui, Y. X. Cui, I. De Mitri, Francesco Palma, A. Di Giovanni, T. K. Dong, Z. X. Dong, Giacinto Donvito, David Droz, J. L. Duan, K. K. Duan, R. R. Fan, Y. Z. Fan, F. Fang, K. Fang, C. Q. Feng, Lei Feng, J. M. Frieden, P. Fusco, M. Gao, F. Gargano, Essna Ghose, Ke Gong, Y. Z. Gong, D. Y. Guo, J. H. Guo, Shuo Han, Yi-Ming Hu, G. S. Huang, X. Y. Huang, Y. Y. Huang, M. Ionica, Leijie Jiang, Yue Jiang, Wei Jiang, Jie Kong, Andrii Kotenko, Dimitrios Kyratzis, S. J. Lei, W. H. Li, W. L. Li, Xiangnan Li, Xuanle Li, Y. M. Liang, C. M. Liu, H. Liu, J. Liu, S. B. Liu, Yang Liu, F. Loparco, M. Ma, Peng-Xiong Ma, T. Ma, X. Y., G. Marsella, M. N. Mazziotta, D. Mo, X. Y. Niu, A. Parenti, Weiyu Peng, Peng Xu, C. Perrina, Enzo Putti-Garcia, Rui Qiao, J. N. Rao, R. Sarkar, P. Savina, Andrea Serpolla, Z. Shangguan, W. H. Shen, Z. Q. Shen, Ziyue Shen, Leandro Silveri, J. X. Song, M. Stolpovskiy, Hong Su, Meng Su, Haoliang Sun, Z. Y. Sun, A. Surdo, X. J. Teng
Abstract
Secondary cosmic ray fluxes are important probes of the propagation and interaction of high-energy particles in the Galaxy. Recent measurements of primary and secondary cosmic ray nuclei have revealed unexpected spectral features that demand a deeper understanding. In this work we report the direct measurement of the cosmic ray boron spectrum from $10\text{ }\text{ }\mathrm{GeV}/\mathrm{n}$ to $8\text{ }\text{ }\mathrm{TeV}/\mathrm{n}$ with eight years of data collected by the Dark Matter Particle Explorer (DAMPE) mission. The measured spectrum shows a hardening at $182\ifmmode\pm\else\textpm\fi{}24\text{ }\text{ }\mathrm{GeV}/\mathrm{n}$ with a spectral index of ${\ensuremath{\gamma}}_{1}=3.02\ifmmode\pm\else\textpm\fi{}0.01$ before the break and an index change of $\mathrm{\ensuremath{\Delta}}\ensuremath{\gamma}=0.31\ifmmode\pm\else\textpm\fi{}0.05$ after the break. A simple power law model is disfavored at a confidence level of $8\ensuremath{\sigma}$. Compared with the hardenings measured in the DAMPE proton and helium spectra, the secondary boron spectrum hardens roughly twice as much as these primaries, which is consistent with a propagation related mechanism to interpret the spectral hardenings of cosmic rays observed at hundreds of $\mathrm{GeV}/\mathrm{n}$.