Energy Release in Nuclear Reactions, Neutrons, Fission, and Characteristics of Fission

Abstract

While this book is not intended to be a history of nuclear physics, it will be helpful to set the stage by briefly reviewing some relevant discoveries. To this end, we first explore the discovery of the enormous energy release characteristic of nuclear reactions, research that goes back to Ernest Rutherford and his collaborators at the opening of the twentieth century; this is covered in Sect. 1.2. Rutherford also achieved, in 1919, the first artificial transmutation of an element (as opposed to this happening naturally, such as in an alpha-decay), an issue we examine in Sect. 1.3. Nuclear reactors and weapons cannot function without neutrons, so we devote Sect. 1.4 to a fairly detailed examination of James Chadwick’s 1932 discovery of this fundamental constituent of nature. The neutron had almost been discovered by Irène and Frédéric Joliot-Curie, who misinterpreted their own experiments. They did, however, achieve the first instance of artificially inducing radioactive decay, a situation we examine in Sect. 1.5, which also contains a brief summary of events leading to the discovery of fission. In Sects. 1.6, 1.7, 1.8, 1.9, 1.10, and 1.11 we examine the process of fission, the release of energy and neutrons during fission, and explore why only certain isotopes of particular heavy elements are suitable for use in fission weapons. Before doing any of these things, however, it is important to understand how physicists notate and calculate the energy liberated in nuclear reactions. This is the topic of Sect. 1.1.