The Lost Notebook of ENRICO FERMI : The True Story of the Discovery of Neutron Induced Radioactivity This book tells the curious story of an unexpected finding that sheds light on a crucial moment in the development of physics: the discovery of artificial radioactivity induced by neutrons. The finding in question is a notebook clearly written in Fermis handwriting which records the frenzied days and nights that Fermi spent experimenting alone driven by his theoretical ideas on beta decay. The notebook was found by the authors while browsing through documents left by Oscar DAgostino the chemist among Fermis group. From Fermis notes they reconstruct with skill and expertise the detailed timeline of the critical days leading up to his vital discovery. While much is already known about the road that led Fermi to his important result this is the first time that it has been possible to reconstruct precisely when and how the initial evidence of neutron induced decay was obtained. In relating this fascinating story the book will be of great interest not only to those with a passion for the history of science but also to a wider audience. Introduction. 1 Fermi in Italy: his handwritten manuscripts. 2 Fermi Archive at the Domus Galilaeana in Pisa. 3 A hole in the Archive. 4 How do we proceed. 5 The start of Nuclear Physics in Rome. 6 Fermi and Nuclear Physics: the first steps. 7 The first international congress of Nuclear Physics: Rome October 1931. 8 An accurate scientific planning. 9 “Nuclear” electrons and the “neutrino” at the Rome congress 10 Nuclear Physics in Rome after the Rome Congress: 1931 1133. 11 The discovery of the neutron 12 Fermi at the 1932 Paris Congress. 13 Orso Mario Corbino and particle accelerators. 14 The official start of Nuclear Physics in Rome: March 1933. 15 New particles and new theories. 16 The positron or “anti electron”. 17 The positron in the laboratory 18 The theory of nucleus according to Heisenberg Majorana. 19 Solvay Congress and Fermi theory of nuclear beta decay: October Dicember 1933. 20 The Seventh Solvay Congress. 21 Fermi theory of beta decay. 22 The discovery of alpha particle induced radioactivity. 23 Frédéric Joliot and Irène Curie after the Solvay Congress. 24 The discovery of alpha particle induced radioactivity. 25 Why alpha particle induced radioactivity is discovered only in January. 26 After the discovery. 27 The discovery of neutron induced radioactivity. 28 A project set aside. 29 Gian Carlo Wick contribution. 30 A very good starting point. 31 A precedent case: Fluorine. 32 The discovery of neutron induced radioactivity and the charge sign 33 After the discovery. 34 Fermi strategic choices 35 A firm believe in the neutron. 36 The choice of the source. 37 The exploitation of the “geometry”. 38 Fermi at work: chronicle of a discovery. 39 The Hirpine Notebook. 40 The right side of the notebook. 41 The counter. 42 The inverted periodic table. 43 The moment of the discovery. 44 From Aluminum to Fluorine and more. 45 The investigation on the periodic table and the start of team work. 46 The gamma rays from the source. 47 First chemical analysis and new nuclear reactions. 48 The date and the hour of the discovery. 49 Further developments and conclusion. Fermi publications during the italian period. Appendix (Letters to Majorana). References. Name Index. Figure captions and credits. Pictures. Pages from Hirpine Notebook and Loose Sheets.