Measurement of the cosmic-ray proton spectrum from 40 GeV to 100 TeV with the DAMPE satellite

TL;DR

This paper presents the first high-statistics measurement of cosmic-ray protons from 40 GeV to 100 TeV using DAMPE, revealing spectral features that inform the understanding of cosmic ray origins and acceleration.

Contribution

It provides the first direct measurement of cosmic-ray protons up to ~100 TeV with high statistics, confirming spectral hardening and discovering a softening at ~13.6 TeV.

Findings

Confirmed spectral hardening of cosmic-ray protons.

Discovered a spectral softening at ~13.6 TeV.

Suggests a new spectral feature below the knee energy.

Abstract

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 two and a half years of data recorded by the DArk Matter Particle Explorer (DAMPE). This is the first time an experiment directly measures the cosmic ray protons up to ~100 TeV with a high statistics. The measured spectrum confirms the spectral hardening 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.