Precise measurements of the cosmic ray proton energy spectrum in the "knee'' region

Abstract

We report the high-purity identification of cosmic-ray (CR) protons and a precise measurement of their energy spectrum from 0.15 to 12 PeV using the Large High Altitude Air Shower Observatory (LHAASO). Abundant event statistics, combined with the simultaneous detection of electrons/photons, muons, and Cherenkov light in air showers, enable spectroscopic measurements with statistical and systematic precision comparable to satellite data at lower energies. The proton spectrum shows significant hardening relative to low-energy extrapolations, culminating at 3 PeV, followed by sharp softening. This distinct spectral structure closely aligned with the knee in the all-particle spectrum points to the emergence of a new CR component at PeV energies that might be linked to the dozens of PeVatrons recently discovered by LHAASO, and offers crucial clues to the origin of Galactic cosmic rays.

References in corpus (9)

• Global cosmic-ray related luminosity and energy budget of the Milky Way
• The First LHAASO Catalog of Gamma-Ray Sources
• Observation of Spectral Structures in the Flux of Cosmic-Ray Protons from 50 GeV to 60 TeV with the Calorimetric Electron Telescope on the International Space Station
• Measurements of All-Particle Energy Spectrum and Mean Logarithmic Mass of Cosmic Rays from 0.3 to 30 PeV with LHAASO-KM2A
• Ultra-High-Energy Gamma-Ray Bubble around Microquasar V4641 Sgr
• DAMPE proton spectrum indicates a slow-diffusion zone in the nearby ISM
• A Three-component Model for Cosmic-ray Spectrum and Dipole Anisotropy
• Understanding the phase reversals of Galactic cosmic ray anisotropies
• Large-scale anisotropy of Galactic cosmic rays as a probe of local cosmic-ray propagation

Cited by in corpus (7)

• Microquasar jet-cocoon systems as PeVatrons
• Precise Measurement of the Cosmic Ray Helium Spectrum above 0.1 PeV
• LHAASO Galactic Plane $\gamma$-rays Strongly Constrain Heavy Dark Matter
• TeV-PeV Gamma-ray and Neutrino Emission in the Galactic Plane
• Joint constraint on the propagation origin of the cosmic-ray spectral knee from energy spectrum and anisotropy observations
• Suppressed diffusion and gamma-ray emission from the Cygnus bubble
• The Cosmic-ray Knee as a Local Signature of Nearby PeVatrons