THE MANHATTAN PROJECT

THE MANHATTAN PROJECT

On August 2, 1939, the physicists Einstein and Szilard sent a letter to the President of the United States Franklin Delano Roosevelt. The letter informed the President that Germany was planning atomic bombs.

On December 7, 1941, Japan attacked Pearl Harbor, Hawaii, and destroyed much of the American military fleet.

The United States government with the support of the United Kingdom and Canada decided to build three research sites in isolated places to make the atomic bomb before the Germans.

THE PLACES

- Oak Ridge(Tennessee) - Los Alamos (New Mexico) - Hanford (Washington)

Oppenheimer, as scientific director of the Los Alamos laboratory, contacted the most brilliant scientific.Leslie Groves was a military head of the Manhattan Project. The Manhattan Project was a research program that produced, during the Second World War, the first nuclear devices.

THE PEOPLE WHO PARTiCIPATED

- the Italian Emilio Segrè who discovered plutonium-239; - the British James Chadwick who demonstrated the existence of the neutron; - the Italian Enrico Fermi who described the formation of isotopes and built a prototype nuclear reactor “Chicago Pile-1” using graphite and uranium; - the Germans Otto Hahn and Fritz Strassmann who produced nuclear fission; - the Hungarian physicist Leó Szilárd who developed the theory of the chain reaction of nuclear fissions. -Danish physicist Niels Bohr who worked in quantum mechanics and atomic structure

At the headquarters of Los Alamos some scientists make a fission bomb. The fission reaction divided the atoms of Uraniums isotopes (Uranium 235 or Uranium 233) or Plutoniums isotopes 239 into smaller particles thus causing a mass defect.

URANIUM

In nature there are two types of Uranium: the 238 and 235 isotopes. The Uranium 235 enriched could be used in nuclear centrals and in atomic bombs. The Uranium, after extraction from mines, is converted into a mix of Uraniums oxides, called “Yellow cake”.

Then it is transformed into Uranium hexafluoride gas (gasification phase). The gas is introduced into a centrifuge and heated. After the centrifuge, the Uranium 235 and the Uranium 238 get separated through the gravity force.

Two types of bomb were created: the bomb of Uranium 235, called “Little Boy”, and the bomb of Plutonium (bigger and heavier) called “Fat Man”.

LITTLE BOY

CRITICAL MASS

When a neutron gets in contact with an atom of Plutonium or Uranium with a top mass of 230, the atom divides into two smaller cores releasing ENERGY. In turn, the cores release neutrons that affect other atoms releasing energy.

Little Boy bomb had low efficacy. Indeed, only 1.5% of fissile Uranium was involved in the fission, while the 98.5% of Uranim was not. This Uranim got disintegrated and settled on Hiroshima as radioactive material.

FAT MAN

THE IMPLOSION PRINCIPLE

When the explosive set off it generated a shock wave that crushed the core thus making a critical mass which triggered the nuclear reaction. The principle of implosion was definitely more efficient than the "gun-type" principle. It allowed to use less nuclear fuel and to increase the destructive power.

TRINITY TEST

On july 16, 1945 scientists conducted “the Trinity nuclear test” where they launched the Gadget bomb to test the performance of the two nuclears bombs previously made. The scientists realized that the world had now entered the nuclear age.

The two atomic bombs caused the instant death of 129000 people and over 110000 got injured. After that, the Japan surrendered. There were many deaths from radiation too.

The physicist Szilard presented to the United States president Truman a petition signed by 68 scientists to ask not to throw the atomic bombs to Japan, because the German nuclear project was still being developed.

PRESENT BY:

THANK YOU FOR YOUR ATTENTION

• Andrea Ciuffreda
• Sergio Della Valle
• Mattia Monfardini

BIBLIOGRAPHY:Focus,Treccani,Mondadori, National Geographic, Università Federico II, Il Sole 24 Ore Mondo, Geopop.

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