A Grand Tour of Nuclear Fission Physics
W. Younes
1 Introduction
In a practical sense, modern nuclear physics began in 1932 with the discovery of the
neutron by James Chadwick [1]. Shortly thereafter, Enrico Fermi working in Rome
set out to form elements beyond uranium, the heaviest known element at the time,
by bombarding a uranium target with neutrons. Fermi surmised that the composite
system produced by the neutron-induced reaction would form higher-Z elements
through a series of beta decays. These experiments lasted from 1934 to 1935, and
although they observed beta activity, Fermi and his collaborators were never able
to account for the large number of separate activities they measured [2, 3]. Despite
this setback, other groups led by Irène Joliot-Curie in Paris and Lise Meitner in
Berlin took up the search for transuranic elements from 1935 to 1938, using Fermi’s
approach [4]. All these attempts were doomed from the start because low-energy
neutron-induced reactions on uranium targets paradoxically lead to fission products
much lighter than the target, rather than to transuranic elements. The concept of
nuclear fission, and the possibility that it might account for Fermi’s results, was
first formulated by Ida Noddack in 1934 [5]. Unfortunately, her prescient critique
of Fermi’s work was largely ignored. The uranium irradiation puzzle was finally
solved in 1938 by the Berlin group with the identification of barium as one of the
products formed in the reaction [2, 6]. In 1939, three seminal papers on fission were
published. The first, by Hahn and Strassmann [7], marked the official discovery of
fission. The second, by Meitner and Frisch [8], gave a model of fission using an
analogy with a drop of liquid. The third paper, by Bohr and Wheeler [9], applied
the liquid-drop model to interpret and predict an impressive number of fission
W. Younes ()
Lawrence Livermore National Laboratory, Livermore, CA, USA
© This is a U.S. government work and not under copyright protection
in the U.S.; foreign copyright protection may apply 2021
J. Escher et al. (eds.), Compound-Nuclear Reactions, Springer Proceedings in
Physics 254, https://doi.org/10.1007/978-3-030-58082-7_34
261
W. Younes
1 Introduction
In a practical sense, modern nuclear physics began in 1932 with the discovery of the
neutron by James Chadwick [1]. Shortly thereafter, Enrico Fermi working in Rome
set out to form elements beyond uranium, the heaviest known element at the time,
by bombarding a uranium target with neutrons. Fermi surmised that the composite
system produced by the neutron-induced reaction would form higher-Z elements
through a series of beta decays. These experiments lasted from 1934 to 1935, and
although they observed beta activity, Fermi and his collaborators were never able
to account for the large number of separate activities they measured [2, 3]. Despite
this setback, other groups led by Irène Joliot-Curie in Paris and Lise Meitner in
Berlin took up the search for transuranic elements from 1935 to 1938, using Fermi’s
approach [4]. All these attempts were doomed from the start because low-energy
neutron-induced reactions on uranium targets paradoxically lead to fission products
much lighter than the target, rather than to transuranic elements. The concept of
nuclear fission, and the possibility that it might account for Fermi’s results, was
first formulated by Ida Noddack in 1934 [5]. Unfortunately, her prescient critique
of Fermi’s work was largely ignored. The uranium irradiation puzzle was finally
solved in 1938 by the Berlin group with the identification of barium as one of the
products formed in the reaction [2, 6]. In 1939, three seminal papers on fission were
published. The first, by Hahn and Strassmann [7], marked the official discovery of
fission. The second, by Meitner and Frisch [8], gave a model of fission using an
analogy with a drop of liquid. The third paper, by Bohr and Wheeler [9], applied
the liquid-drop model to interpret and predict an impressive number of fission
W. Younes ()
Lawrence Livermore National Laboratory, Livermore, CA, USA
© This is a U.S. government work and not under copyright protection
in the U.S.; foreign copyright protection may apply 2021
J. Escher et al. (eds.), Compound-Nuclear Reactions, Springer Proceedings in
Physics 254, https://doi.org/10.1007/978-3-030-58082-7_34
261