=================================================================================

Experimentally, with an incident monochromous beam of X-ray photons, or electrons, or neutrons, the differential cross-section can be given by,
          ----------------------- [2672a]
where,
          j₀ -- (= dN₀/(dt cm²)) The current-density of the beam.  
          Ω -- The solid angle.
          dN_s/dt -- The number of counts per second.

Then, we can have,
          ----------------------- [2672b]

Figure 2672 indicates the dΩ. Equation 2672b also defines the range of angles through which the electron can be scattered.

Figure 2672. Schematic illustration of scattering of an electron by a single atom.