The explosive device was officially designed as “Y-1561 device“, but it was nicknamed “The Gadget” since August 1944. Consisted of an implosion-design plutonium device, similar to the one that would be installed in the Fat Man bomb that would explode over Nagasaki few weeks later. The core was an almost solid sphere and was compressed to produce a supercritical mass with the implosion generated by the high explosive lens. The radioactive core was composed of two semi-spheres of silver-plated plutonium-gallium alloy designated HS-1 and HS-2. The whole set weighed 6.19 kg and generated a heat that caused its temperature rised from 38 to 43º C, which caused blisters on the silver layer that must have been filled with gold foil. This image shows “The Gadget” in the assembly stage inside the tower.A Gadget’s mounting test was carried out on July 3 1945, and the explosives lenses to be used were selected from two different sets. The leftover set was exploded to evaluate the actual performance, and gave such results that the team feared that final test would be a failure. A later study of data made that same night, indicated the explosion would be perfect. The assembly of the nuclear capsule began on July 13 1945 at McDonald Ranch House. The initiator of polonium-beryllium, designated as “Urchin”, was set up, which would be responsible for feeding the reaction with neutrons and was installed between the two plutonium hemispheres. Then, this core was placed inside the uranium slug and the air gaps were filled with gold foil. The two halves of the uranium slug were joined with uranium washers and screws and the complete capsule was brought to the base of the shot tower. This image shows the Gadget in the assembly stage inside the shot tower.The nuclear capsule, 48 kg in weight, was installed inside the Gadget on July 13 1945, and it was raised to the top of the 30 meter high shot tower where it would be exploded. Trinity was armed and ready for the test around 10 p.m. from July 15 1945. After the explosion, the tower vanished leaving only a small part of one of their four legs. A crater of 1.50 meters deep and 9.10 meters wide was produced. It was calculated that yield was 21 kilotons, 15 coming from the fission of the plutonium and 6 from the uranium-235 fission, with which the slug containing the plutinium core was built. This image shows the Trinity Gadget fully assembled and ready for testing.The Manhattan Project began in 1939, and the United States leads the development with the support of the United Kingdom and Canada. The British-Canadian part was known as “Tube Alloys” and actually started before the Manhattan Project. At the beginning of WWII, the German physicist Rudolf Peierls and the Austrian physicist Otto Frisch from the University of Birmingham wrote a report in which they described as a small amount of pure uranium-235, could trigger a chain reaction in a bomb with the power of thousands of tons of TNT. This image shows the fireball at 0.006 seconds after the explosion.The efforts of the Manhattan Project focused on separating isotopes of uranium-235 from the most abundant uranium-238 to obtain the fissile material that generated the chain reaction. In 1941 President Roosevelt approved the start of the atomic program, and from 1942, the theoretical physicist Robert Oppenheimer entered the project along with a team of outstanding theoretical and experimental physicists. This image shows the fireball at 0.016 seconds after the explosion.The achievement of uranium-235 isotopes, and of a new material discovered in 1941 and known as plutonium, was not an easy task at all and four methods were studied to obtain it. These were: by electromagnetic separation, by gaseous diffusion, by thermal diffusion and by gas centrifuges. The problem is that in 1942 there were no reactors to obtain the precious uranium-235. On the other hand, only two milligrams of plutonium had been obtained until December 1943 by “cyclotrons”, a kind of particle accelerator. This image shows the fireball at 0.025 seconds after the explosion, at this time the fireball had a diameter of about 250 meters.After verifying that a fission bomb was theoretically possible, the best way to bring the fissile material to its critical mass was studied. The most effective way, was to shoot a cylindrical plug against a sphere of active material that had a dense material inside that directed the neutrons inward and kept the reactive mass together to improve efficiency. Scientists began to discuss the possibility of creating an even more powerful bomb, (the hydrogen bomb), which was a fusion bomb, but this issue was stopped to dump all efforts in the fission bomb. This image shows the fireball at 0.053 seconds after the explosion.The Manhattan Project grew exponentially and at the end of 1942 several places were acquired to carry out the works. The principal ones were Los Alamos in New Mexico, Oak Ridge in Tennessee and Hanford Site in Washington, although in 1946, when the Project was terminated, there were more than 30 sites connected to the Project. In Los Alamos Laboratory, known as “Project Y” and in charge of the University of California, the first 4 nuclear bombs in history were designed and developed. At Oak Ridge, the Clinton Engineer Works produced the enriched uranium used in the Hiroshima bombing as well as the creation of reactors for the production of plutonium. And at Hanford Site, the first World’s plutonium production reactor, or “B Reactor”, was built. From here came the plutonium necessary for the Trinity device and the “Fat Man” bomb launched on Nagasaki. This image shows the fireball at 0.062 seconds after the explosion, at this moment the fireball has a diameter of about 360 meters.Another problem that had to be faced was to get enough uranium ore from which to extract the precious isotopes. There were only 4 deposits in the World from which it was possible to extract the necessary quantities of ore. They were located in Northern Canada, in the Belgian Congo, in Jachymov (Czechoslovakia) and in Colorado state. After buying some 2,000 tons of ore, the Mallinckrodt company transformed them into pure uranium oxide, which later had to be converted into uranium metal. This work was carried out by Metal Hydrides and Westinghouse companies, but it was a very difficult issue that was improved in a place known as “Ames Project”, located in Iowa, Since July 1943 they managed to produce nearly 60 tons of uranium metal monthly. This image shows the fireball at 0.090 seconds after the explosion.Uranium metal, composed by 99.3% uranium-238 and 0.7% uranium-235, must be treated in order to separate both components and get uranium-235, which was the fissile and useful material for the bombs. Three methods were combined to produce the required amounts of uranium-235. The thermal diffusion enriched the uranium from 0.7 to 0.89%, then, this material was passed through the gaseous diffusion process with which it rose to 23%. Finally, this material was processed by electromagnetic separation to achieve an enrichment of 89%, enough for the production of nuclear weapons. The obtaining of fissile plutonium-239 was somewhat less difficult and was achieved in nuclear reactors by bombarding natural uranium with neutrons, and then separating the fissile isotopes in a very complicated process.This image shows the fireball at 2 seconds after the explosion.The results of the Trinity explosion could not foresee in no way, although a test had been performed to calibrate the measuring instruments. On May 7, 1945, 91 tons of “Composition B”, (a mixture of TNT and RDX explosives), together with tubes containing 1000 curies of reactor fission products were exploiting on a 6.10 meteres high wooden platform. This test known as “The 100 ton test” only served to measure the blast wave of the explosion and how the radioactive material could be distributed when exploding. This image shows the fireball at 3 seconds after the explosion.The scientists of the project did not have all with them and Enrico Fermi came to comment their fear that the atmosphere could catch fire causing the end of the World. There was also concern about the possible cracking of the Earth’s crust. These considerations may seem absurd today, but we must keep in mind the context of the test and the general ignorance of the consequences of the explosion. This image shows the fireball at 4 seconds after the explosion.Robert Oppenheimer, the project’s chief scientist, Kenneth Bainbridge, head of the technical team and other personalities were in a concrete bunker designated S-10,000. It had been designated by the distance that separated it from the 30-meter shot tower where the explosion would take place. Leslie Grooves, the General in charge of the project, had been located 32 km away, along with scientists such as Edward Teller or Hans Bethe in case something “went wrong”. This image shows the fireball at 7 seconds after the explosion, it can be seen how the atomic mushroom begins to form.The start time of the test had been set for 04:00 a.m., but had to be delayed due to a strong storm with lightning striking the area. Finally at 05:08 a.m., Oppenheimer, ignoring the meteorological forecasts that advised against the test, gave the order to begin with the detonation sequence. At this time many of the scientists of the project thought that the test would be the biggest fiasco in history and put an end to the dream after three years of unimaginable top-secret efforts. This image shows the fireball at 15 seconds after the explosion.Finally at 05:29:45 a.m. the circuit was closed and the TNT began its work. Suddenly a blinding light, and then a gigantic shock wave along with a rumble as never before had confirmed to Oppenheimer and the rest of his team that the first atomic explosion of History had taken place. It was at this time that Oppenheimer remembered a phrase from the Hindu poetry book “Bhagavad Gita” which read: “Now I am become Death, the destroyer of worlds”. This image shows the Trinity‘s explosion at maximum power, with an estimated power equivalent to 21,000 tons of TNT.The clouds that covered the place colored pink as the fireball ascended. Then, it was transformed into a gigantic sphere that fell slowly on itself and took on an intense purple color. The sand of the desert turned into trinitite, a kind of greenish glass, the shock wave could be felt 160 km away and the mushroom cloud reached 12,100 meters high. The shock wave took 40 seconds to reach the observers located 32 km away and the heat they felt was described as coming out from an open oven. This image shows what from that day would be the archetype of maximum destruction in the broadest sense of the word.
