Measurements of Cosmic-Ray Hydrogen and Helium Isotopes with the PAMELA Experiment

The cosmic-ray hydrogen and helium (<SUP>1</SUP>H, <SUP>2</SUP>H, <SUP>3</SUP>He, <SUP>4</SUP>He) isotopic composition has been measured with the satellite-borne experiment PAMELA, which was launched into low-Earth orbit on board the Resurs-DK1 satellite on 2006 June 15. The rare isotopes <SUP>2</SUP>H and <SUP>3</SUP>He in cosmic rays are believed to originate mainly from the interaction of high-energy protons and helium with the galactic interstellar medium. The isotopic composition was measured between 100 and 1100 MeV/n for hydrogen and between 100 and 1400 MeV/n for helium isotopes using two different detector systems over the 23rd solar minimum from 2006 July to 2007 December.