Nuclear reaction cross-section ( $σ (E)$ )

The effective area for a specified nuclear reaction channel at given incident energy. Multiplying incident particle flux, target count and this cross section gives an ideal event rate; target losses and detection efficiency require separate corrections.

Table of contents
- Macroscopic nuclear reaction cross section Nuclear reaction cross-section
- Neutron absorption cross section Nuclear reaction cross-section

Macroscopic nuclear reaction cross section ( $Σ = \sum_{i} N_{i} σ_{i}$ )

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A reaction coefficient formed from target number densities and microscopic nuclear reaction cross-sections. It has inverse-length units. Multiplying it by the scalar neutron flux gives the corresponding reaction rate per volume, under the stated energy averaging.

Neutron absorption cross section ( $σ_{a}$ )

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A cross section for removal of an incident neutron by absorption, including capture and neutron-induced fission where relevant. Its value depends on nuclide and neutron energy.