State Key Laboratory of Particle Detection and Electronics, University of Science and Technology of China, Hefei 230026, China.
Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China.
Sci Adv. 2019 Sep 27;5(9):eaax3793. doi: 10.1126/sciadv.aax3793. eCollection 2019 Sep.
The precise measurement of the spectrum of protons, the most abundant component of the cosmic radiation, is necessary to understand the source and acceleration of cosmic rays in the Milky Way. This work reports the measurement of the cosmic ray proton fluxes with kinetic energies from 40 GeV to 100 TeV, with 2 / years of data recorded by the DArk Matter Particle Explorer (DAMPE). This is the first time that an experiment directly measures the cosmic ray protons up to ~100 TeV with high statistics. The measured spectrum confirms the spectral hardening at ~300 GeV found by previous experiments and reveals a softening at ~13.6 TeV, with the spectral index changing from ~2.60 to ~2.85. Our result suggests the existence of a new spectral feature of cosmic rays at energies lower than the so-called knee and sheds new light on the origin of Galactic cosmic rays.
精确测量宇宙辐射中最丰富的质子的能谱对于理解银河系中宇宙射线的起源和加速至关重要。本工作报告了利用暗物质粒子探测卫星（DAMPE）记录的 2 年数据，对能量在 40GeV 到 100TeV 之间的宇宙射线质子通量的测量。这是首次用高统计量直接测量到 ~100 TeV 的宇宙射线质子。测量得到的能谱证实了之前实验发现的在 ~300GeV 处的谱硬化现象，并揭示了在 ~13.6TeV 处的软化现象，谱指数从 ~2.60 变化到 ~2.85。我们的结果表明，在所谓的膝部以下能量存在宇宙射线的新谱特征，这为银河系宇宙射线的起源提供了新的线索。
