Modern Physics

Nuclear fission

Breakdown of the nucleus through neutrons

In the late 1930s, physicist Lise Meither and chemists Otto Han and Fritz Stranssmann, working in Berlin continuing the work of Fermi and his collaborators, they exposed solutions of uranium salts to thermal neutrons and found that some products of this interaction were radioactive.

In 1939, one of the radium nuclides produced in this way was identified as barium.
According to researchers Meitner and Otto Frisch, a uranium nucleus, after absorbing a thermal neutron, split with energy release into two approximately equal fragments, one of which was barium. Frisch called it fission.

Nuclear Fission can be explained through the collective model, which is based on an analogy between the nucleus and an electrically charged drop of liquid endowed with a certain excitation energy. For fission to occur, the fragments must overcome a potential barrier, for which the excitation energy Em must be of the same order as the height of the barrier Eb.

In short:For the nuclear fission process to release large amounts of energy, one fission event must produce other events, causing the process to spread through nuclear fuel like fire in a piece of wood. The fact that two or more neutrons are released in each fission event is essential for the occurrence of this type of chain reaction, in which each neutron produced can cause a new fission that can be explosive or controlled, that is, it is a process where the “breaking” of the uranium nucleus occurs, and in this break several nuclear reactions take place simultaneously.

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