Neutron cross section according to its neutron cross section and how it reacts to an incident neutron. Nuclides that tend to absorb a neutron and either decay or keep the neutron in its nucleus are neutron absorbers and will have a "capture cross section" for that reaction. Isotopes that fission, are fissionable fuels and have a corresponding "fission cross section". The remaining isotopes will simply scatter the neutron, and have a "scatter cross section". Some isotopes, like uranium-238, have nonzero cross sections of all three. Isotopes which have a large scatter cross section and a low mass are good neutron moderators (see chart
Cross section (geometry) plane containing a cross-section of the solid may be referred to as a "cutting plane". The shape of the cross-section of a solid may depend upon the orientation of the cutting plane to the solid. For instance, while all the cross-sections of a ball are disks, the cross-sections of a cube depend on how the cutting plane is related to the cube. If the cutting plane is perpendicular to a line joining the centers of two opposite faces of the cube, the cross-section will be a square, however, if the cutting plane is perpendicular to a diagonal of the cube