The radar system for which Alvarez is best known and which has played a major role in aviation, most particularly in the post war Berlin airlift, was Ground Controlled Approach (GCA).

Luis Walter Alvarez was born into a Roman Catholic family in San Francisco on June 13, 1911, the second child and oldest son of Walter C. Alvarez, a physician, and his wife Harriet née Smyth, and a grandson of Luis F. Álvarez, a Spanish physician, born in Asturias, Spain, who lived in Cuba for a while and finally settled in the United States, who found a better method for diagnosing macular leprosy.

[13] After he completed his oral exams in 1936, Alvarez, now engaged to be married to Geraldine Smithwick, asked his sister to see if Lawrence had any jobs available at the Radiation Laboratory.

Using magnets to sweep aside the positrons and electrons emanating from his radioactive sources, he designed a special purpose Geiger counter to detect only the "soft" X-rays coming from K capture.

At that time the stability of these two reaction products was unknown, but based on existing theories Hans Bethe thought that tritium would be stable and helium-3 unstable.

[23] The British Tizard Mission to the United States in 1940 demonstrated to leading American scientists the successful application of the cavity magnetron to produce short wavelength pulsed radar.

But VIXEN transmitted a radar signal whose strength was the cube of the distance to the submarine so that as they approached the sub, the signal—as measured by the sub—got progressively weaker, and the sub assumed the plane was getting farther away and did not submerge.

[28] The radar system for which Alvarez is best known and which has played a major role in aviation, most particularly in the post-war Berlin airlift, was Ground Controlled Approach (GCA).

Using Alvarez's dipole antenna to achieve a very high angular resolution, GCA allows ground-based radar operators to watch special precision displays to guide a landing airplane to the runway by transmitting verbal commands to the pilot.

[29] Alvarez was awarded the National Aeronautic Association's Collier Trophy in 1945 "for his conspicuous and outstanding initiative in the concept and development of the Ground Control Approach system for safe landing of aircraft under all weather and traffic conditions".

[30][31] Alvarez spent the summer of 1943 in England testing GCA, landing planes returning from battle in bad weather, and also training the British in the use of the system.

Clarke subsequently used his experiences at the radar research station as the basis for his novel Glide Path, which contains a thinly disguised version of Alvarez.

[33] In the fall of 1943, Alvarez returned to the United States with an offer from Robert Oppenheimer to work at Los Alamos on the Manhattan Project.

It was decided to use a nearly critical sphere of plutonium and compress it quickly by explosives into a much smaller and denser core, a technical challenge at the time.

[37] Again working with Johnston, Alvarez's last task for the Manhattan Project was to develop a set of calibrated microphone/transmitters to be parachuted from an aircraft to measure the strength of the blast wave from the atomic explosion, so as to allow the scientists to calculate the bomb's energy.

[38] Flying in the B-29 Superfortress The Great Artiste in formation with the Enola Gay, Alvarez and Johnston measured the blast effect of the Little Boy bomb which was dropped on Hiroshima.

[40] Returning to the University of California, Berkeley as a full professor, Alvarez had many ideas about how to use his wartime radar knowledge to improve particle accelerators.

Though some of these were to bear fruit, the "big idea" of this time would come from Edwin McMillan with his concept of phase stability which led to the synchrocyclotron.

Refining and extending this concept, the Lawrence team would build the world's then-largest proton accelerator, the Bevatron, which began operating in 1954.

Though the Bevatron could produce copious amounts of interesting particles, particularly in secondary collisions, these complex interactions were hard to detect and analyze at the time.

[41] Seizing upon a new development to visualize particle tracks, created by Donald Glaser and known as a bubble chamber, Alvarez realized the device was just what was needed, if only it could be made to function with liquid hydrogen.

By suddenly reducing the pressure in the device, the liquid could be placed into a temporary superheated state, which would boil along the disturbed track of a particle passing through.

This work was a large effort, carrying detectors aloft with high-altitude balloon flights and high-flying U-2 aircraft, and an early precursor of the COBE satellite-born experiments on the cosmic background radiation (which resulted in the award of the 2006 Nobel Prize, shared by George Smoot and John Mather[46]).

By measuring the counting rate of the cosmic rays in different directions the detector would reveal the existence of any void in the overlaying rock structure.

[47] Alvarez assembled a team of physicists and archeologists from the United States and Egypt, the recording equipment was constructed and the experiment carried out, though it was interrupted by the 1967 Six-Day War.

Restarted after the war, the effort continued, recording and analyzing the penetrating cosmic rays until 1969, when he reported to the American Physical Society that no chambers had been found in the 19% of the pyramid surveyed.

[48] In November 1966, Life magazine published a series of photographs from the 1963 "Zapruder film", believed to be the most complete document of the assassination of John F. Kennedy.

[2] Alvarez had access to the nuclear chemists at the Lawrence Berkeley Laboratory and was able to work with Frank Asaro and Helen Michel, who used the technique of neutron activation analysis to study the clay.

[52] In the years following the publication of their article, the clay was also found to contain soot, glassy spherules, shocked quartz crystals, microscopic diamonds, and rare minerals formed only under conditions of great temperature and pressure.

Ten years later, after Alvarez's death, evidence was found of a large impact crater off the coast of the Yucatán peninsula in Mexico, providing support for the theory.