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The 10-foot 8-inch (3.25 metres) long, five-foot (1.52 metres) diameter, 10,000-pound (4545 kg) weapon detonated at an altitude of about 1,800 feet (550 m) over the city. It was dropped from the B-29 bomber Bockscar, piloted by Major Charles Sweeney. The bomb had a yield of about 20 kilotons, or 8.4×1013 joule = 84 TJ ( terajoule), slightly more than the bomb known as " Little Boy" dropped on Hiroshima three days earlier. Due to Nagasaki's hilly terrain, the damage was somewhat less extensive than that in relatively flat Hiroshima. An estimated 73,900 people died in the nuclear explosion at Nagasaki.
"Fat Man" was an implosion type weapon using plutoniumPlutonium is a radioactive, metallic, chemical element. It has the symbol Pu and the atomic number 94. Its atomic weight is 244. 06, its density 19,800 kg/m3. It is the element used in most modern nuclear weapons. The most important isotope of plutonium i. A subcritical sphere of plutonium was placed in the center of a hollow sphere of high explosive. Numerous detonatorsThe exploding-bridgewire detonator (EBW) was invented by Luis Alvarez and Lawrence Johnston for the Fat Man-type bombs of the Manhattan Project. The implosion had to be very symmetric or the plutonium would simply squirt out at the low- pressure points. located on the surface of the high explosive were fired simultaneously to produce a powerful inward pressurePressure (symbol: p is a measure of force per unit area. where p is the pressure F is the force A is the area Often F is taken to be the of the magnitude of the mean vector force normal to the surface of area A upon which it exerts; the "surface" not nece on the capsule, squeezing it and increasing its density, resulting in a supercritical condition and a nuclear explosion.
This mechanism was necessary for a plutonium weapon in contrast to a uranium weapon (like "Little Boy") because the gun mechanism used in "Little Boy" (firing two sub-critical masses together into one super-critical mass) would have been impractical. Plutonium has a higher spontaneous neutron emissionNeutron emission is a type of radioactive decay in which a neutron is simply ejected from the nucleus. An example isotope which emits neutrons is Beryllium-13. See also neutron radiation Radioactivity. rate than uranium, and so two masses fired together would begin chain reactions before they formed a supercritical mass, resulting in a 'fizzle', or explosion with no fissile component. It is theoretically possible to build a plutonium gun-type device, but it would need to be 19 feet long in order to allow the sub-critical masses to be fused into a critical mass before a fizzle occurs. The mass of a plutonium gun-type device would have been beyond the payload of the B-29.
Earlier there had been one test explosion with this type of weapon (called the "gadget"), on July 16July 16 is the 197th day (198th in leap years) of the year in the Gregorian Calendar, with 168 days remaining. Events 622 Beginning of the Islamic calendar. 1769 First performance of Mozart's opera The Abduction from the Seraglio. 1769 Father Junipero Ser, 1945, at the Trinity siteThe Trinity site is the site of the first testing of a nuclear weapon, on July 16, 1945. A plutonium bomb was tested, the kind that was used in Nagasaki (no uranium bomb was ever tested before using one in Hiroshima). The site was part of the Alamogordo B, due to worries about how the mechanism would perform in practice. In the end, it gave somewhere around 20 kt, 2 to 4 times the expected yield.
The Soviet UnionThe Union of Soviet Socialist Republics (USSR ( Russian: ; tr. Soyuz Sovetskikh Sotsialisticheskikh Respublik (SSSR) also called the Soviet Union ( ; tr. Sovetsky Soyuz , was a state in much of the northern region of Eurasia that existed from 1922 until 1's first nuclear weapon detonated at Operation First Lightning was more or less a purposeful copy of the Fat Man device.
Schematic cross-section of Gadget; some boundaries are approximate. From left to right (outside inward):