What's the role of a neutron in fission?

In fission, a neutron initiates the process by colliding with a heavy nucleus, causing it to split into smaller nuclei.

In nuclear fission, the role of a neutron is crucial. It acts as a catalyst to initiate the process. Fission is a nuclear reaction in which a heavy nucleus, such as uranium-235 or plutonium-239, splits into two or more smaller nuclei, along with the release of a large amount of energy. This process begins when a neutron collides with the heavy nucleus. The collision causes the nucleus to become unstable and split.

The neutron that initiates the fission process is often referred to as a 'slow' or 'thermal' neutron. This is because it has been slowed down to thermal energies, which increases the likelihood of it being captured by the heavy nucleus. Once the neutron is absorbed, it increases the mass of the nucleus, pushing it into an unstable state. This instability leads to the nucleus splitting, or fissioning, into two smaller nuclei.

The fission process also releases additional neutrons. These neutrons can then go on to cause further fissions, creating a chain reaction. This chain reaction is the principle behind nuclear power and atomic bombs. In a nuclear power plant, the chain reaction is carefully controlled to ensure a steady release of energy. In an atomic bomb, the chain reaction is uncontrolled, leading to a rapid, explosive release of energy.

In summary, the neutron plays a pivotal role in nuclear fission. It initiates the process by colliding with and being absorbed by a heavy nucleus, causing it to become unstable and split. The fission process also releases additional neutrons, which can trigger further fissions, creating a chain reaction.