Knowra Geiger–Marsden experiment Geiger–Marsden experiment A 1909 experiment in which alpha particles were scattered by thin gold foil, with a small fraction deflected through unexpectedly large angles. Its results led Ernest Rutherford to propose a compact, positively charged atomic nucleus.
Rutherford scattering : The elastic scattering of charged particles by a Coulomb force, especially alpha particles by atomic nuclei. The experiment’s large-angle events are explained by Coulomb repulsion from concentrated positive charge.
Hans Geiger : A German physicist who developed particle-detection methods and helped establish nuclear physics. He conducted the scattering work that gave the experiment its name.
Rutherford model : An atomic model with a tiny, dense, positively charged nucleus surrounded by electrons. Rutherford proposed this structure to explain the experiment’s rare, sharp deflections.
Geiger–Marsden 1909 paper : A paper reporting measurements of alpha-particle scattering from thin metal foils, published by Hans Geiger and Ernest Marsden in 1909. It records the measurements that exposed the unexpectedly frequent large-angle deflections.
Alpha particle : A helium-4 nucleus consisting of two protons and two neutrons, emitted in some radioactive decays. These were the projectiles fired at the gold foil.
Ernest Marsden : A New Zealand physicist who investigated alpha-particle scattering under Ernest Rutherford’s direction. As a student, he observed the rare large-angle deflections that prompted Rutherford’s interpretation.
Atomic nucleus : The small, dense, positively charged center of an atom, containing nearly all its mass. The scattering evidence showed that positive charge and most atomic mass occupy a compact center.
Geiger–Marsden 1913 experiment : A follow-up study by Hans Geiger and Ernest Marsden testing how alpha-particle scattering varies with foil thickness and material. Its measurements further tested the scattering pattern associated with concentrated atomic charge.
Gold foil : A thin sheet of gold used as a target in particle-scattering experiments. Its thinness let most alpha particles pass through while some encountered strong deflections.
Ernest Rutherford : A New Zealand-born physicist who established the nuclear model of the atom and studied radioactivity. He proposed the nuclear explanation for the scattering results.
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