Luis Walter Alvarez

American Physicist and pioneer of the bubble chamber technique in particle physics


His father was a medical researcher in California and later in the Mayo Clinic, his grandmother was from Spain and she moved to Los Angles to make her money in real estate. His mother was originally from Ireland. Alvarez enrolled in the University of Chicago in 1928 and started to study Chemistry but when he took a course called “Advanced Experimental Physics: Light” he said that “it was love at first sight”.

East West Effect

His advisor in Chicago was Nobel Laureate Arthur Compton, Alvarez said the he only visited him once which suited him. In one of his graduate projects he co-discovers the East-West Effect – which states that the amount of cosmic rays depends on what direction you examine from.

Prize Wild Idea Man

After getting his degree and doctorate from Chicago he married Geraldine Smithwick, a colleague in Chicago. They moved to Berkeley, California and joined Nobel Laureate E.O. Lawerence as a research scientist. His colleagues nickname him “prize wild idea man” because he was interested in so many areas of physics. Hans Bethe predicted that an excited nucleus could decay by capturing one of its own orbiting electrons, this became known as K-electron capture. Due to the fact that the electron is absorbed from the K electron shell, changing a proton into a neutron. Alvarez successfully detected this process.

Mercury and Magnetic Moment

Alvarez with a student Jake Weins created a Mercury vapour lamp, which was used by the US Bureau of Standards as a standard for length. He co-developed a method for producing a beam of very slow moving neutrons, which lead to the discovery of neutron scattering in hydrogen, with Pitzer, and to the first measurement, with Noble Laureate Felix Bloch, of the magnetic moment of the neutron.


Just before the breakout of World War in Europe, Alvarez and Cornog discovered H3 (tritium) and showed that He3 was a stable constituent of ordinary helium. Tritium is best known as a source of thermonuclear energy, and 3He has become of importance in low temperature research.


During the war, Alvarez joined the MIT Radiation Laboratory (nicknamed The Rad Lab) working on Radar (Radio detecting and ranging) systems. While there he invented three new radar systems. 1. The Eagle high altitude bombing system – bombing system which enables a pilot to bomb a target without a clear line of sight. 2. A microwave early warning system – a way of detecting aircraft in motion in cloud skies. 3. A system for landing “blind” in fog or bad weather called the Ground-Controlled Approach. GCA for a while had the highest priority in the Rad Lab, because more planes were lost trying to land in Britain than were shot down by the Nazis.

The Bomb

Alvarez joins the Manhattan Project in Los Alamos in 1943, developing the detonators for setting off the plutonium bomb. This was not a simple task as the bomb had to fire in 32 different locations simultaneously. He flew in a B-29 bomber behind “Enola Gay” after they dropped the first atomic bomb on Hiroshima, Japan.

Bubbles and Accelerators

After the war, Alvarez concentrated on high energy research in Berkeley and constructed a 40 foot proton linear accelerator. In 1950, he had a chance meeting with Donald Glaser, who had recently invented the bubble chamber. This was a device for detecting particles by leaving a trail of bubbles in superheated fluid (the story has it that he invented it after seeing bubbles in a glass of beer). Alvarez realized that he could improve Glaser’s chamber by using Hydrogen instead of ether and he developed a system to record the vast number of interactions. After several years, he developed a 72 inch chamber and went on to discover several unknown particles, the first of which was the “Y-particle”, which he discovered in 1960.


In 1965, he went to Egypt to examine the Pyramid of Kefren at Giza, to detect if there were any hidden rooms. The team fired a beam of muons, the X-ray component of cosmic radiation, at the pyramids and examined the relative density of the structure, they concluded that there were no hidden chambers.


In 1963, he was requested by the Warren Commission to investigate the assassination of John F Kennedy. He examined the Zapruder film and showed that it was possible that the president’s head could have gone back even if the bullet came from that direction.

Dinosaurs and Asteroids

With his son Walter, a geologist, they discovered a layer of rock in the Italian Apennines that contained a high level of iridium a rare earth metal. This layer was sandwiched between rock from the Cretaceous and Tertiary periods, around 65 million years ago. They first suggested that the iridium might have come from a nearby supernova but the layer did not contain other elements, typical of a supernova. In 1980, they published a paper, saying that they believe that the Iridium came from an asteroid (10 Kilometres in length) hitting the earth. This explosion caused the sun to be blocked out and lead to the extinction of the dinosaurs.


As well as the radar inventions, Alvarez had 30 patents and was elected to the National Inventors Hall of Fame. He also invented an indoor golf training device for President Eisenhower. He was awarded the Noble Prize for Physics in 1968 for his work on the bubble chamber and the particle that he discovered with it. He was interest in so many areas and had a very creative mind. He died of cancer in Berkley, in 1988.

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