Rutherford scattering: a standalone construct

Ernest Rutherford's 1911 paper The scattering of α and β particles by matter and the structure of the atom introduced Rutherford scattering: the deflection of a fast, positively charged particle as it passes near an atom, caused by the electric (Coulomb) repulsion between the particle and a tiny, dense, positively charged core at the atom's centre. Rutherford derived it to account for the 1909 observation by Hans Geiger and Ernest Marsden that a small fraction of alpha particles fired at a thin gold foil bounced almost straight back, a result that the then-current picture of the atom as diffuse positive matter could not explain. In the model the scattering is elastic, meaning the particle keeps its kinetic energy and only changes direction, and the probability of scattering through a given angle follows a formula that varies as one over the fourth power of the sine of half the deflection angle and as the square of the nuclear charge. That angular pattern is the construct's signature: it placed essentially all of an atom's positive charge and mass in a nucleus far smaller than the atom, and it remains the standard description of low-energy elastic scattering by the Coulomb field, used to determine nuclear charge and to analyse material surfaces.[1][2]

Unit

A scattering process characterised by its differential cross-section, the probability of deflection into each angle

Recovery means

Not applicable

Measured by

Identified by counting scattered particles as a function of deflection angle and comparing the angular distribution to the Coulomb cross-section