Measurement of the p+He energy spectrum with the DAMPE space mission

Abstract

It is currently well established that proton and helium constitute the main component of cosmic radiation in the energy range from tens of GeV to hundreds of TeV. Their direct detection and separation have been carried out in the past years using several space-based instruments and long-flying balloons, while ground-based experiments provided results at high energies but with large systematics due to the limited mass resolution. Surprisingly, two structures were found in the direct measurements of individual proton and helium spectra which deviates from the single power law model, proposed by standard acceleration and propagation mechanisms. Moreover, results from ground-based experiments opened the scenario of a light component (i.e. p+He) knee in the cosmic ray spectrum, even with large uncertainties. The p+He direct measurement, using looser selection cuts compared to individual p and He analyses, besides giving a valuable cross-check, can enlarge the event statistics and then extend the energy range to larger values, covering an overlap region between direct and indirect measurements, and exploring it for the first time with high precision. Among the space-based cosmic ray detectors in operation at present, the DArk Matter Particle Explorer (DAMPE) has the capability of providing results on p+He up to the highest energies, thanks to its large acceptance and deep calorimeter. In this work, the p+He spectrum measured up to 300 TeV, using 6 years of data collected with the DAMPE satellite, will be presented.

DArk Matter Particle Explorer: 7 years in Space

“…While agreeing well with the previously reported individual proton and helium spectra, this analysis extends to a much higher kinetic energy of 316 TeV, thanks to significantly larger combined statistics. Intriguingly, the new results suggest a hint of a new spectral hardening at ∼150 TeV [36], establishing at the same time a strong link between space-and ground-based experiments.…”