1. Nuclear Physics to Fission

2. Ernest Rutherford 1911-1912: Rutherford proposed nuclear model of atom
1919: Succeeded J. J. Thomson as director of Cavendish Laboratory at Cambridge
1920s and 1930s: Made Cavendish a “Mecca” of nuclear physics

3. James Chadwick and Neutron
Irene and Frederick Joliot-Curie and others discovered new penetrating rays
James Chadwick proved in 1932 that the rays were new fundamental particles that Rutherford had speculated on: a neutral particle with mass similar to protons
Rutherford: Nobel for Chadwick and the Curies would surely win theirs
Curies: discovery of artificial radioactivity in 1934 and Nobel
Also in 1932: Discovery of Positron by Carl Anderson

4. Path to Fission Slow neutron effects: Enrico Fermi in 1930s
Lise Meitner, Otto Hahn, and Fritz Strassmann
Bombardment of uranium with neutrons
Meitner forced to flee Germany in 1938
Christmas 1938: Hahn and Strassmann’s experimental results and Meitner and Frisch’s theoretical explanation