Measurements of He isotopic ratio in cosmic rays in the 100 MeV – 1 GeV range with the PAMELA experiment

The PAMELA satellite-borne experiment was launched on 15 June 2006 from the Baikonur cosmodrome and it has been collecting data since then. The apparatus comprises a time-of-flight system, a silicon-microstrip magnetic spectrometer, a silicon-tungsten electromagnetic calorimeter, an anticoincidence system, a shower tail counter scintillator and a neutron detector. The combination of these devices allows precision studies of the charged cosmic radiation to be conducted over a wide energy range (100 MeV – 1 TeV) with high statistics, with particular focus on the antiparticle component. In this work we present 3He/4He isotopic ratio in the energy range from 100 MeV nucleon 1 to ~1 GeV nucleon 1. The measured abundances are compared with different interstellar/heliospheric propagation calculations which are tuned on previous proton and helium measurements.