= Multiple Coulomb scattering
{c}
<Multiple Coulomb scattering> is the accumulated deflection of a <charged particle> passing through matter, mainly through repeated <Rutherford scattering> by <atomic nucleus>[atomic nuclei]. Many small deflections broaden a beam or make a reconstructed particle track wander. A roughly <Gaussian distribution> describes the central angular core in a useful regime, while rarer large-angle encounters produce tails.<Passage of Particles Through Matter by Donald E. Groom and Spencer Klein>[§34.3, Multiple scattering through small angles: nuclear Coulomb deflections, Gaussian core and non-Gaussian tails]{ref}
The angular width increases with traversed material and decreases as particle <momentum> increases. It is commonly parameterized using material thickness relative to the <radiation length>. In a <particle detector>, adding measurement layers can improve position sampling while also increasing <Multiple Coulomb scattering>; track precision therefore depends on material as well as sensor accuracy. A width projected onto one measurement plane must be distinguished from the full spatial deflection angle.
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