Short History of Nuclear Decays Including Nuclear Fission

Abstract

A short history of the different kinds of nuclear decay modes (α decay, β decay, γ decay, induced fission, spontaneous fission, ternary and multi-cluster fission, fissioning shape isomers, and cluster radioactivities) is presented below, showing how the important research activities at the end of 19th century and the beginning of the 20th one, lead to the discovery of atomic nucleus by Ernest Rutherford in 1911. We shall start with X-rays —a precursor of all these phenomena. The first observation of alpha-, beta-, and gamma radiations was made by Antoine Henri Becquerel in 1896, who observed that beta-rays are deviated by a magnetic field. Marie and Pierre Curie coined the name radioactivity after they produced two new elements: polonium and radium. Alpha particles were first described in the investigations of radioactivity by Ernest Rutherford in 1899, and by 1907 they were identified as He 2+ ions. In 1928, George Gamow had solved the theory of alpha decay via tunneling through a potential barrier. The alpha particle is trapped in a potential well by the nucleus. According to the principles of quantum mechanics, it has a small probability of tunneling through the barrier and escape from the nucleus. Gamow solved a model potential for the nucleus and derived, from first principles, a relationship between the half-life of the decay, and the energy of the emission, which had been previously discovered empirically, and was known as the Geiger-Nuttall law.