  Cosmic rays were discovered by Victor Hess in 1912 through their effect on
the conductivity of the atmosphere. It took several decades of research to
understand their nature and composition. The photographic method of particle
detection, developed and refined by Marietta Blau, played an important part in
making visible cosmic-ray reactions in nuclear emulsions as disintegration
stars in 1937. In the high atmosphere, cosmic-ray reactions produce not only
charged particles, but also neutrons which lead to the formation of
radiocarbon. The dating technique based on 14C was developed in 1946 by Willard
Libby. The present work describes how members of the Institute for Radium
Research in Vienna contributed to the discovery of cosmic rays, disintegration
stars as well as the application of radiocarbon dating.
