What is the Difference Between Neutron Capture and Absorption?

05/15/2025 • Matheus Moraes

The key difference between neutron capture and neutron absorption lies in the nuclear reactions they describe. While both processes involve the combination of a nucleus and a neutron to form a compound nucleus, the methods of combination are different:

Neutron capture refers to the (n, gamma) reaction, where a collision occurs between a nucleus and a neutron, resulting in the capture of the neutron by the nucleus and the subsequent emission of a gamma-ray photon. This process is also known as "radiative capture". Neutron capture is a common way of producing radioactive isotopes.
Neutron absorption refers to any reaction involving the formation of a compound nucleus, including the (n, gamma) reaction, fission, and other reactions that are not just scattering. In the neutron absorption process, a fission occurs. Neutron absorptions produce an isotope that decays by beta emission.

In summary:

Neutron capture involves a collision between a nucleus and a neutron, resulting in the capture of the neutron and the emission of a gamma-ray photon.
Neutron absorption involves any reaction involving the formation of a compound nucleus, including fission and other reactions.

Comparative Table: Neutron Capture vs Absorption

Here is a table comparing the differences between neutron capture and neutron absorption:

Process	Description	Key Features
Neutron Capture	A collision occurs between a nucleus and a neutron, forming a compound nucleus.	- Involves the (n, gamma) reaction. - Results in the formation of unstable nuclei, which may undergo nuclear decay and form other fissile nuclei.
Neutron Absorption	A fission occurs between a nucleus and a neutron, forming a compound nucleus.	- Involves any reaction involving the formation of a compound nucleus, including capture, fission, and other reactions that aren't scattering. - Generally follows the kinetics of fission reactions. - The end product tends to divide into two parts while releasing some energy.

Both neutron capture and neutron absorption are nuclear reactions that involve the combination of a nucleus and a neutron to form a compound nucleus. However, the method of combination is different. Neutron capture is a specific reaction used in nuclear reactors, while neutron absorption is a more general term that includes various reactions involving the formation of a compound nucleus.