= Hans Geiger
{c}
{tag=Physicist}
{title2=1882–1945}
= H. Geiger
{c}
{synonym}
<Hans Geiger> and <Ernest Marsden> counted large-angle deflections of <alpha particles> from metal targets. Their 1909 work used visible scintillations to register particles scattered back toward the incident side, establishing that rare strong deflections required explanation. Their 1913 measurements tested the angular dependence more systematically with thin targets. Comparing count rates with target thickness, incident <energy> and observation angle helped turn the concentrated-charge picture of <Rutherford scattering> into a quantitative experimental test.<The Laws of Deflexion of Alpha Particles through Large Angles by Hans Geiger and Ernest Marsden>[1913 paper, experimental angular and target-dependence tests]{ref}
A <physicist>.https://www.tu.berlin/en/about/history/people-portraits/hans-geiger[Independent biographical identity and professional specialization]{ref}
\Image[https://upload.wikimedia.org/wikipedia/commons/a/ad/Hans_geiger.jpg]
{title=Portrait of <Hans Geiger>}
{width=240}
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