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Incoming links: Dictionary of New Zealand Biography Marsden, Ernest by Ross Galbreath
Ernest Marsden Created 2026-10-18 Updated 2026-11-05
Ernest Marsden and Hans Geiger observed alpha particles scattered through large angles by metal targets. Counting weak scintillations supplied an event-based readout even when only a small fraction of the incident beam returned toward its source. The observation challenged descriptions that attributed all deflections to many weak encounters. Their later measurements varied geometry and target conditions to test the single-scattering interpretation behind Rutherford scattering.[ref]
On a Diffuse Reflection of the Alpha-Particles by Hans Geiger and Ernest Marsden. 1909 paper, pp. 495–500, apparatus and reflected-particle counting
A physicist.[ref]
Marsden, Ernest by Ross Galbreath. Dictionary of New Zealand Biography; Independent biographical identity and professional specialization
Portrait of Ernest Marsden
. S. P. Andrew Ltd.; National Library of New Zealand collection, photograph dated 1921. The Commons File records expired-copyright public-domain status in the United States., via Wikimedia Commons. Source.
Geiger-Marsden experiment 2026-10-18
The Geiger-Marsden experiment probes the interior of a chemical atom by counting alpha particles deflected by metal foils. The surprising observation was a small population returning towards the incident side. Hans Geiger and Ernest Marsden performed the experiments under Ernest Rutherford's direction; Ernest Rutherford developed the Rutherford model in 1911. Observation and interpretation were distinct contributions.[ref]
Marsden, Ernest by Ross Galbreath. Dictionary of New Zealand Biography; Biography, paragraphs on the 1909 undergraduate experiment and subsequent interpretation
In 1909, a radon source and its radioactive decay products in a conical glass tube supplied alpha particles through a mica window towards a reflector. Lead shielded a fixed zinc sulfide screen from direct hits; an optical microscope resolved individual particle scintillations. Reflectors occupied the same position. Reflector-out counts tested air scattering; stacked gold foils and bare glass tested thickness and support contributions.[ref]
On a Diffuse Reflection of the Alpha-Particles by Hans Geiger and Ernest Marsden. On a Diffuse Reflection of the α-Particles, printed pp. 495–498, Fig. 1 and experiments I–II
Nearby source geometry blurred incidence angles. Extrapolating platinum counts uniformly over a hemisphere was an assumption, not a universal reflection probability.[ref]
On a Diffuse Reflection of the Alpha-Particles by Hans Geiger and Ernest Marsden. Printed pp. 497, 499–500, angular limitation and experiment III