Walther Bothe

Walther Bothe (1891–1957) was a German physicist who developed coincidence methods, studied cosmic rays and nuclear reactions, and shared the 1954 Nobel Prize in Physics.

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Hans Geiger: A German physicist who developed radiation detectors and worked with Walther Bothe on particle coincidence experiments. Their joint experiments used Geiger counters to establish whether detected particles arrived together.
Coincidence counting: A detection method that registers events occurring within a specified time interval in separate detectors. Bothe and Geiger used simultaneous detector signals to test whether particles were physically connected.
Bothe–Geiger experiment: A 1924 experiment using coincidence counting to investigate the conservation of energy and momentum in Compton scattering. It established a precise experimental method that became central to Bothe’s work.
1954 Nobel Prize in Physics: The physics Nobel awarded jointly to Walther Bothe and Max Born for separate contributions to the understanding of quantum mechanics. Bothe was recognized for coincidence methods and discoveries made with them.
James Chadwick: A British physicist who discovered the neutron in 1932 through experiments on beryllium radiation. Chadwick interpreted Bothe and Becker’s penetrating radiation as evidence for a neutral particle.
Geiger counter: A gas-filled detector that produces an electrical pulse when ionizing radiation triggers a discharge. Its pulses supplied the timed signals at the heart of Bothe’s coincidence experiments.
Bothe–Becker experiment: A 1930 experiment reporting penetrating radiation produced when alpha particles struck beryllium. The radiation Bothe and Herbert Becker found was later identified as evidence of neutrons.
Cosmic ray: High-energy particles and associated radiation arriving at Earth from space or produced in the atmosphere. Bothe’s coincidence experiments helped establish that cosmic rays include charged particles.
Irène Joliot-Curie: A French physicist and chemist who, with Frédéric Joliot-Curie, investigated radiation from bombarded elements. Her experiments on beryllium radiation helped prompt Chadwick’s neutron interpretation.
Compton scattering: The inelastic scattering of a photon by a charged particle, typically an electron, with a change in wavelength. Bothe and Geiger tested whether scattered X-rays and recoiling electrons appeared in coincidence.