Greenhouse George

Greenhouse George was an American nuclear test conducted on May 8, 1951, as part of Operation Greenhouse. It was the first instance of thermonuclear fusion brought about by humans, i.e. energy release from atomic nuclei colliding at very high temperatures. It yielded 225 kilotons TNT equivalent. The Cylinder device was designed for probing the thermonuclear reaction. It was a test of the radiation implosion principle that was key to the recently theorized Teller-Ulam design. The vast majority of its yield derived from fission. The energy output from the thermonuclear fusion in this test was insignificant in comparison.

Greenhouse George
The George mushroom cloud
Information
Country	United States
Test series	Operation Greenhouse
Test site	Enewetak
Date	May 8, 1951
Test type	Atmospheric
Yield	225 kt
Test chronology
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Background

The first Soviet nuclear test, RDS-1, took place on August 29, 1949. It was detected and announced to the world by United States president Harry Truman on September 23, 1949. The American nuclear establishment, aware of the theoretical possibility of thermonuclear weapons since the early days of the Manhattan Project, vigorously debated whether they should be pursued. On January 31, 1950, Truman issued a statement regarding the United States' program to develop the hydrogen bomb^[1].

On March 9, 1951, American nuclear physicists Edward Teller and Stanisław Ulam wrote a report outlining their Teller-Ulam design, the basis for thermonuclear weapons.

Design

The Cylinder device for the George test.

The Cylinder device was designed specifically to allow observation of the thermonuclear reaction. The fission component was a unique cylindrical implosion of a long highly enriched uranium annulus. This surrounded a beryllium oxide chamber, containing cryogenic liquid deuterium with a few percent tritium. Tritium was still scarce at the time, likely produced in the B, D, and F reactors at the Hanford Site, but deuterium–tritium fusion, around 100 times more likely than deuterium-deuterium fusion, was hoped to increase the number of DD reactions. The beryllium oxide chamber and fusion fuel was to be imploded by the fission reaction's X-ray radiation, allowing observation of the fusion plasma before it was engulfed.

The George design was a 'Classical Super' prototype with a binary triggering device based on the one patented by Klaus Fuchs and von Neumann in 1946.^[2] Its success played a vital role in the history of the Teller–Ulam design.

Test

University of California Radiation Laboratory provided the scientists for the measurement of the fusion reaction. Complex equipment was developed for isolating the fusion radiation from the simultaneous fission detonation. Vacuum pipes carried the fusion X-rays to the base of a shot tower, where K-edge filters fluoresced for optical measurement. Unshielded photographic plates were exposed to the high-energy fusion neutrons, and their collision with the emulsion produced signature "proton streaks".^[3]

Edward Teller pessimistically made a $5 bet with Ernest Lawrence that the device would not work i.e. thermonuclear reactions would not be detected. He paid Lawrence the following morning when the detection of 14 MeV neutrons was confirmed.^[4]

The George Test had a perfect “bell” Wilson cloud formed near the top of the mushroom cloud.

The George test validated the principles which would be used for the first full-scale thermonuclear bomb test, Ivy Mike, one year later, on November 1, 1952, at Enewetak Atoll.

Gallery

• 
  George explosion
• 
  George mushroom cloud

See also

• Operation Greenhouse
• Greenhouse Item
• Edward Teller