1. Chronology of Radiation Science 400 B.C. Democritus proclaims all material things are made of tiny particles, which he calls “atoms” 1789 Martin Klaproth discovers uranium (Germany) 1869 Dmitri Mendeleyeev develops the Periodic Table 1895 Wilhelm Roentgen discovers X-rays (Germany)

2. Chronology of Radiation Science 1896 Henri Becquerel discovers some atoms give off energy in the form of rays (France) 1898 Marie and Pierre Curie discover radium (France) The term “radioactivity” is first used (Marie Curie) 1899 Ernest Rutherford classifies alpha and beta “rays” 1900 Pierre Curie observes gamma rays

3. Chronology of Radiation Science 1905 Albert Einstein publishes the Special Theory of Relativity, equating mass and energy (E = mc 2 ) 1905 First food irradiation patents issued (US & Europe) 1911 Ernest Rutherford identifies the atomic nucleus 1911 George de Hevesy credited with first use of radioisotope tracers

4. Chronology of Radiation Science 1913 Neils Bohr develops the theory of atomic structure 1913 Hans Geiger invents the Geiger counter 1920 Ernest Rutherford discovers and names the proton 1927 First use of radioactive tracer to diagnose heart disease (Herman Blumgart at Boston City Hospital)

5. Chronology of Radiation Science 1932 James Chadwick discovers the neutron Early 1930s The first artificial radioactive isotopes are created (Irene Joliot-Curie and her husband Frederic) 1938 Otto Hahn and Fritz Strassman produce lighter elements by bombarding uranium with neutrons Lise Meitner and Otto Frisch recognize the Hahn- Strassman results as nuclear fission

6. Chronology of Radiation Science 1942 First self-sustaining fission chain reaction produced (Enrico Fermi, et al., December 2, Chicago) 1945 First atomic bomb detonated 1951 First significant electric power generated from nuclear energy (100 kw, Arco, Idaho) 1954 First nuclear-powered submarine, USS Nautilus, goes to sea (Groton, CT)

7. Chronology of Radiation Science 1956 First full-scale nuclear power plant begins operation (Calder Hall, England) 1957 First US commercial nuclear power plant begins operation (Shippingport,PA) 1961 First radioisotope-powered remote weather station installed, 700 miles from the North Pole

8. Chronology of Radiation Science 1965 First commercial nuclear power plant in Michigan begins operation (Big Rock Point, Charlevoix) 1965 World’s first commercial irradiation plant for food processing commissioned in Canada 1966 First commercial liquid metal fast breeder nuclear power plant begins operation (Fermi I, Monroe)

9. Chronology of Radiation Science 1973 X-ray scanners mandated for use at US airports 1979 Nuclear plant accident at Three Mile Island, PA 1983 Powered by a nuclear generator, Pioneer 10 becomes the first human-made object to leave the solar system, 11 years after launch 1984 Nuclear power becomes the second-largest producer of electric power in the US (after coal)

10. Chronology of Radiation Science 1986 100 th US commercial nuclear power plant begins operation (Perry-1, near Cleveland) 1986 Nuclear plant accident at Chernobyl, Ukraine 1992 First U.S. commercial food irradiation plant ships irradiated strawberries to 5 states and 2 foreign countries