Donald Glaser invented the bubble chamber

Person: Donald Glaser
Lived: 1926–2013
Field: Physics, biotechnology
From: American

The story

Donald Glaser was born in Cleveland in 1926 to Russian Jewish immigrants. After a doctorate on cosmic rays at Caltech, he joined the University of Michigan in 1949, just as new accelerators were producing a flood of short-lived particles that physicists could barely see. The standard detector, the cloud chamber, recorded tracks as trails of droplets in a gas, but gas is thin, so fast particles rarely interacted inside it, and the chambers could not keep up with accelerator beams.

Glaser’s answer, worked out in 1952, was to use a liquid. If a liquid is held under pressure above its boiling point and the pressure is suddenly released, for a moment it is superheated and ready to boil. A charged particle passing through leaves a trail of ionised atoms along which bubbles form, and a photograph taken a split second later shows its path as a line of bubbles. Because a liquid is far denser than a gas, the tracks are sharp and the interactions frequent. His first prototype was a small glass vessel filled with ether. He denied the popular story that a glass of beer gave him the idea, though he admitted trying beer in early tests, and he described the device as “a pressure cooker with windows.”

He scaled it up fast. By 1954 he and his student David Rahm had taken a propane chamber to the Cosmotron at Brookhaven, and he tested liquid hydrogen as a filling. His own experiments measured the lifetimes, decay patterns and spins of several new strange particles.

Laboratories around the world then built ever larger chambers filled with liquid hydrogen and other liquids, and for two decades they were the workhorses of particle physics, producing millions of photographs that teams of scanners measured track by track. The Berkeley physicist Herbert Steiner said the invention was a major breakthrough that led to the discovery of a zoo of new particles. Making sense of that zoo led physicists toward the quark model and the Standard Model of particle physics. Glaser received the 1960 Nobel Prize in Physics at the age of 34.

Why it matters

The bubble chamber let physicists see and measure subatomic particles directly, opening the path to the quark model and today’s Standard Model of matter.

About Donald Glaser

Physicist who invented the bubble chamber, which revealed a zoo of new particles, then turned to biology and co-founded Cetus, the first biotechnology company, where PCR was born.

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Donald Glaser

1926–2013 · Physics, biotechnology

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