Mass resolution for helium isotopes in AMS-02

AMS-02 determines the mass and the isotopic composition of the helium cosmic rays nuclei in the kinetic energy range 0.5-10 GeV/n by means of the measurements of the momentum and velocity of the particles. A precise knowledge of the detector response to helium nuclei is required to accomplish these measurements. In this work, we present a detailed study of the mass resolution for helium isotopes comparing the Monte Carlo simulation of AMS with the 5-year data sample taken on the International Space Station.