Cougnet conducted research on cosmic radiation at the Nuclear Plates Laboratory of the National Atomic Energy Commission (CNEA) in Argentina, around 1950, laying the groundwork for the founding of the National Center for Cosmic Radiation (now called the Institute of Astronomy and Space Physics, IAFE) at the University of Buenos Aires in 1960. At the end of 1949, Cougnet went to Germany and visited the laboratory of Werner Heisenberg at the Max Planck Institute in Göttingen where she learned about the work with nuclear emulsions directed by Martin Teucher. In 1950–1951, Cougnet and Juan Roederer, still students, exposed nuclear plates with photographic emulsions at high altitudes in the Andes mountains of Argentina. In that way, they obtained the second reported detection of subatomic particles called pi mesons, or pions. In early 1953, Cougnet and Roederer undertook the last expedition to expose emulsions at higher geomagnetic latitudes, on the slopes of the Lanín volcano near Bariloche, Argentina.