Helium spectrum in the Cosmic Rays measured by the DAMPE detector

Abstract

DAMPE (DArk Matter Particle Explorer) is a space mission promoted by the Chinese Academy of Sciences (CAS), in collaboration with Universities and Institutes from China, Italy and Switzerland. The satellite was launched on December 17th, 2015, and since then DAMPE has been stably collecting data. The DAMPE detector is composed by four sub-detectors: a Plastic Scintillator Detector (PSD), a Silicon Tungsten tracKer-converter (STK), a BGO calorimeter (BGO) and a NeUtron Detector (NUD). Two layers of PSD guarantee full detection efficiency and allow the measurement of the Cosmic Ray charge, up to Iron. Thanks to the STK, the trajectory of the incoming particles is reconstructed with a spatial resolution better than 70 μm within 60° of incidence angle. Furthermore, the BGO calorimeter has a depth of 32 radiation lengths (∼ 1.6 nuclear interaction lengths) and allows the estimation of Cosmic Ray energy with a resolution better than 40% at 800 GeV. Exploiting these features, DAMPE studies the Cosmic Ray flux with unprecedented resolution in an energy range from few tens of GeV up to hundreds of TeV and establishes a bridge between direct and indirect measurements. This work is focused on the Helium analysis and preliminary results on the flux measured up to ∼ 5 TeV/n will be presented and discussed.