1962 Nuclear power plant in the Antarctic becomes operational. 1963 President Kennedy ratified the Limited Test Ban Treaty for the United States on October 7. 1964 President Johnson signed law permitting private ownership of certain nuclear materials. Fission is Explained [Illustration: _Enrico Fermi 1901-1954_ Courtesy Chemical and Engineering News] Physicists welcomed the neutron as a bullet that could strike any nucleus, unopposed by electric repulsion. During the middle 1930s, a number of investigators, chief among them the Italian physicist Enrico Fermi, exposed many different isotopes of the chemical elements to beams of neutrons to see what would happen. What usually happened was that the bombarded nuclei would absorb neutrons, emit alpha, beta, or gamma rays, and change into different isotopes. The identification of the extremely small quantities of isotopes produced required the development of a fantastic new branch of chemistry known as radiochemistry, or, as one chemist put it, “phantom chemistry.” In some cases the absorption of a neutron by a nucleus was followed by the emission of a negative electron (beta particle). This produced an atom whose nuclear positive charge had been increased by one unit and which therefore belonged at the next higher place on the periodic table. Fermi and others then considered the fascinating possibility of doing the same thing to uranium, the last-known element on the periodic table, to create previously unknown chemical elements. The results of bombarding uranium with neutrons turned out to be extremely complex, but it eventually became clear that “transuranic” elements (those heavier than uranium) could actually be made in this way.[2] Some of the complex results of bombarding uranium with neutrons formed an intriguing puzzle that kept various investigators busy for several years. In 1939 the German chemists Otto Hahn and Fritz Strassmann and the physicists Lise Meitner and Otto Frisch were able to announce a solution. The absorption of a neutron by a certain uranium nucleus (later shown to be that of the relatively rare isotope uranium-235) can result in a splitting, or _fission_, of the nucleus into two parts with separate weights that place them somewhere near the middle of the periodic table. [Illustration: _Lise Meitner and Otto Hahn in their laboratory in the 1930s._ Courtesy Addison-Wesley Publishing Co.] The announcement of this discovery created quite a stir among physicists because a nuclear process of this nature must release a very large amount of energy.