The Elemental and Isotopic Composition of Galactic Cosmic Rays

Galactic cosmic rays represent a directly accessible sample of matter that originates outside the solar system. The element and isotope distribution of this high-energy material is a record that was molded in the fires of nucleosynthesis in other regions of the galaxy, and imprinted by subsequent nuclear and electromagnetic processes that have altered its composition. Recently, significant new advances have been achieved in reading this record, brought about in large part by the launch of new high-resolution instrumentation for measuring the charge, mass, and energy distribution of cosmic ray nuclides. In general, the data from these new experiments are telling us what is different about this extra-solar sample. This rapporteur paper reviews progress in this area that was reported at the 17th International Cosmic Ray Conference in Paris. In general, the sessions covered (OG H.2, H.3, 1.1, 1.2) addressed the following questions: