First Atom Bomb

 Trinity is the code name of the first detonation of nuclear weapon conducted by united states army as a part of manhattan project.

First Atom Bomb was invented by J Robert Oppenheimer.

It was detonated on 16 July 1945.

Little Boy is the name of the type of atomic bomb used in the bombing of the Japanese city of Hiroshima on 6 August 1945 during World War II, making it the first nuclear weapon used in warfare. 

The first atomic bomb was built in Los Alamos, New Mexico, during World War II under a top secret U.S. government program called the Manhattan Project. Los Alamos was approved as the site for the main atomic-bomb scientific laboratory on November 25, 1942, by Brigadier General Leslie R. Groves and physicist J. Robert Oppenheimer.

The test was of an implosion-design plutonium bomb, nicknamed "The Gadget", of the same design as the Fat Man bomb later detonated over Nagasaki, Japan, on August 9, 1945.

The code name Trinity was given by Oppenheimer.

The Manhattan Project was a research and development program undertaken during World War II to produce the first nuclear weapons. It was led by the United States in collaboration with the United Kingdom and Canada. From 1942 to 1946, the project was directed by Major General Leslie Groves of the U.S. Army Corps of Engineers. Nuclear physicist J. Robert Oppenheimer was the director of the Los Alamos Laboratory that designed the bombs.

     Photo of detonation of first nuclear weapon.

The project resulted in two types of atomic bombs, developed concurrently during the war: a relatively simple gun-type fission weapon and a more complex implosion-type nuclear weapon. The Thin Man gun-type design proved impractical to use with plutonium, so a simpler gun-type design called Little Boy was developed that used uranium-235. Three methods were employed for uranium enrichment: electromagnetic, gaseous, and thermal. In parallel with the work on uranium was an effort to produce plutonium. After the feasibility of the world's first artificial nuclear reactor, the Chicago Pile-1, was demonstrated in 1942 at the Metallurgical Laboratory in the University of Chicago, the project designed the X-10 Graphite Reactor and the production reactors at the Hanford Site, in which uranium was irradiated and transmuted into plutonium. The Fat Man plutonium implosion-type weapon was developed in a concerted design and development effort by the Los Alamos Laboratory.

For an atomic bomb to explode, a nuclear chain reaction must start.

Two cutaway illustrations are shown. One is for a gun-assembly fission bomb and the other is for an implosion fission bomb.

In a gun-assembly bomb, a mass of uranium-235 is fired down a “gun barrel” toward another mass of U-235 to start the reaction. The cutaway has a neutron initiator surrounded by uranium-235. A conventional explosive and a primer apparatus are on one side of the sphere. The whole bomb has a hard metal casing around it.

In an implosion bomb, a sphere of plutonium-239 is surrounded by high explosives that compress the plutonium. The cutaway has a neutron initiator surrounded by a plutonium-239 core encased in a uranium-238 tamper. Surrounding that are two layers of high-explosive lenses and then a hard metal casing. Multiple wires connect to different points around the outside of the sphere to the firing unit.

The first test

The first test had a code name of Trinity and took place in Alamogordo, New Mexico on July 16, 1945 at 5:29:45 AM. The bomb name was Gadget. The bomb type was plutonium-239 implosion and had a TNT equivalent of 21,000 tons.

The world's first nuclear explosion occurred on July 16, 1945, when a plutonium implosion device was tested at a site located 210 miles south of Los Alamos, New Mexico, on the barren plains of the Alamogordo Bombing Range, known as the Jornada del Muerto. Inspired by the poetry of John Donne, J. Robert Oppenheimer code-named the test "Trinity." Hoisted atop a 100-foot tower, the plutonium device, or "Gadget," detonated at precisely 5:30 a.m. over the New Mexico desert, releasing 18.6 kilotons of power, instantly vaporizing the tower and turning the surrounding asphalt and sand into green glass. Seconds after the explosion came an enormous blast, sending searing heat across the desert and knocking observers to the ground. The success of the Trinity test meant that an atomic bomb using plutonium could be readied for use by the U.S. military.

The Trinity site is now part of the White Sands Missile Range and is owned by the U.S. Department of Defense (DOD). Ground zero is marked by an obelisk made of black lava rock, with an attached commemorative sign. A slightly depressed area several hundred yards across surrounds the monument, indicating where the blast scoured the ground. Only a few pieces of the green glass, trinitite, remain in a protected enclosure. Outside the fenced-in ground zero area lies "Jumbo," the 214-ton steel container built to contain the plutonium if the 5,300 pounds of high explosives in the bomb detonated but no nuclear explosion resulted. Ultimately, Jumbo was not used. The restored McDonald ranch house, where the device's plutonium core was assembled, is located about two miles to the south. The remnants of the base camp where some 200 scientists, soldiers, and technicians took up temporary residence during the summer of 1945 is about ten miles southwest of ground zero. Remnants of the observation points 10,000 yards out are also still visible. The Trinity site is currently opened to the public by the National Park Service twice a year. Tours are given by DOD on request.