= Oliver Cecil Simpson
{c}
{tag=Physicist}
{title2=1909–2002}
= Oliver C. Simpson
{c}
{synonym}
= O. C. Simpson
{c}
{synonym}
<Oliver Cecil Simpson> coauthored atomic-beam measurements using gravitational free fall to investigate the <velocity> distribution of cesium atoms. Gravity makes a particle's displacement depend on its travel time, so slower atoms are deflected more during a given path. For an ideal horizontal flight of length $L$ at speed $v$, the downward displacement is $gL^2/(2v^2)$. The measurement connects a beam's spatial distribution with its microscopic velocities, using gravity as a timing-dependent probe.<The Free Fall of Atoms and the Measurement of the Velocity Distribution in a Molecular Beam of Cesium Atoms by Immanuel Estermann, Oliver Cecil Simpson, and Otto Stern>[Physical Review 71, 238 (1947), atomic free fall and beam-velocity distribution]{ref}
Physics and solid state science.https://physicstoday.aip.org/obituaries/oliver-cecil-simpson[Independent professional profile]{ref}
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{title=Portrait of <Oliver Cecil Simpson>}
{width=240}
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