Geiger counter

1935 Geiger counter

The book of science

Tom Sharp

John Sealy Townsend, Hans Geiger, Walther Müller physics Geiger counter

Geiger counter

You can’t see them shooting, but you can hear them miss with the Geiger counter that you carry. Alpha particle, beta particle, gamma ray zips through the tube where it ionizes an atom to free electrons and ions in an electric avalanche. * The Russians might drop an atom bomb on the school in your town, so you have learned to duck and cover. Now you know your nation must be ready. Assess, prepare, assemble its own tools, its own threats, its own fears. An avalanche, a cascade, a chain reaction. Pretty soon there’s a missile silo on every farm, a nuclear sub in every sea.

Townsend discharge

A gas conducts electricity in a strong electric field when a radioactive particle ionizes an atom of the gas to free other electrons cascading toward the anode and to free other ions cascading toward the cathode.

Maligning atoms

Atoms are all around us; we breathe them and we eat them. You’d like to think they were our friends. You’d like to think they were hard little nuts, not easy to crack. So it took a while to realize the dangers of atomic emissions and that people should not watch test explosions of atomic bombs. Today, Madame Curie’s papers are kept in lead-lined boxes, too dangerous to handle without protective clothing.

John Sealy Townsend became a research student at Cambridge at the same time as Ernest Rutherford, and Hans Geiger studied under Ernest Rutherford at the University of Manchester. Ernest Rutherford distinguished alpha and beta particles. Alpha decay is the emission of a particle containing two protons and two neutrons; beta decay is the emisson of an electron or positron. Gamma radiation is the emision of high-energy photons.

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