Mott scattering

Mott scattering, also referred to as spin-coupling inelastic Coulomb scattering, is the separation of the two spin states of an electron beam by scattering the beam off the Coulomb field of heavy atoms. It is mostly used to measure the spin polarization of an electron beam.

In lay terms, Mott scattering is similar to Rutherford scattering but electrons are used instead of alpha particles as they do not interact via the strong force (only weak and electromagnetic). This enables them to penetrate the atomic nucleus, giving valuable insight into the nuclear structure.

The electrons are often fired at gold foil because gold has a high atomic number (Z), is non-reactive (does not form an oxide layer), and can be easily made into a thin film (reducing multiple scattering). The presence of a spin-orbit term in the scattering potential introduces a spin dependence in the scattering cross section. Two detectors at exactly the same scattering angle to the left and right of the foil count the number of scattered electrons. The asymmetry, A, given by:

${\displaystyle A={\frac {I^{right}-I^{left}}{I^{right}+I^{left}}}}$

is proportional to the degree of spin polarization P according to A = SP, where S is the Sherman function.

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