High-Precision Cosmic-Ray Boron Spectrum Revealed by DAMPE

The Dark Matter Particle Explorer (DAMPE), also known as 'Wukong,' has achieved a significant milestone by obtaining a high-precision cosmic-ray boron spectrum, marking a major advancement in astrophysical research. The collaboration of international scientists reported these findings, which span an energy range from 10 GeV/n to 8 TeV/n, with a notable spectral hardening phenomenon observed around 182 GeV/n for the first time. The results were published in the prestigious journal, Physical Review Letters, on July 3, 2025.

DAMPE, a satellite mission launched by the Chinese Academy of Sciences, is equipped with a state-of-the-art calorimeter made of bismuth germanium oxide. This instrument provides a measurement range that is more than double that of previous cosmic-ray detection experiments. The Plastic Scintillator Detector (PSD), developed by the Institute of Modern Physics (IMP) at the Chinese Academy of Sciences, plays a critical role in identifying cosmic-ray nuclei due to its superior charge measurement capabilities.

The researchers leveraged data from DAMPE to identify a significant hardening feature in the boron spectrum near 182 GeV/n, achieving an impressive confidence level of eight sigma. This phenomenon indicates that the secondary boron spectrum hardens approximately twice as much as that of primary cosmic rays, which include protons and helium nuclei. Furthermore, the data remain consistent with observed trends in boron-to-carbon and boron-to-oxygen flux ratios, supporting existing theoretical models of cosmic-ray interactions.

According to Dr. F. Alemanno, an astrophysicist from the Gran Sasso Science Institute in Italy and a co-author of the study, "These results not only enhance our understanding of cosmic-ray propagation processes but also refine the theoretical frameworks used to describe them." The findings align with the theory that cosmic-ray boron is primarily produced through fragmentation reactions involving primary cosmic rays, such as carbon and oxygen, interacting with interstellar matter.

The implications of this research extend beyond theoretical advancements. The new standard of precision established by DAMPE in measuring cosmic-ray energy spectra at TeV energies opens avenues for further exploration of high-energy astrophysical phenomena. As noted by Dr. Robert Egan, a senior astrophysics researcher at the University of Science and Technology of China, "The ability to measure cosmic-ray boron with such accuracy will lead to more precise models of cosmic-ray sources and their propagation in the galaxy."

In addition to contributing to the scientific community’s understanding of cosmic rays, the research has potential applications in developing advanced detection technologies for various scientific fields. The international collaboration involved institutions such as the Purple Mountain Observatory of the Chinese Academy of Sciences, the University of Science and Technology of China, the Gran Sasso Science Institute, and the University of Geneva, highlighting the global commitment to advancing astrophysical research.

As cosmic-ray research continues to evolve, the findings from the DAMPE mission will undoubtedly play a crucial role in shaping future studies and enhancing our knowledge of the universe. The ongoing exploration of cosmic rays will not only deepen our understanding of fundamental astrophysical processes but may also lead to breakthroughs in related fields such as particle physics and cosmology. As Dr. Alemanno concluded, "This is just the beginning; we expect many more discoveries as we analyze the wealth of data that DAMPE continues to collect."