|Fig. 1: Map of the Trinity Test site. (Source: Wikimedia Commons)|
The Trinity weapon used plutonium, but in a more efficient way than the uranium in the bomb dropped over Hiroshima on August 6th 1945. 
The Trinity test explosion released a quantity of energy of approximately 19,000 tons of TNT, or 38,000,000 pounds of TNT. The explosion generated an incredible bright light at the instant of the explosion (which was visible at 180 miles from the explosion site), a huge ball of fire that reached a height of 10,000 feet and a massive smoke cloud that grew up to 36,000 feet above ground level. 
By 1944, reactor plutonium were started to be used in nuclear bombs.  Partial bomb tests couldn't replace definitive tests of an entire weapon. There were several challenges in the bomb-making process, ranging from hydrodynamics to nuclear physics, thermodynamics to optics and from nuclear chemistry to geophysics. Often they were interrelated, and so solving one problem involved understanding the other fields. 
By the fall of 1944, the Trinity Site, the place for the testing of the bomb, had a base camp where scientists and support staff had settled to finish the bomb and prepare for the test.  People continued to work on the project with absolute secrecy, with the scientists feeling more and more pressure to finish the bomb as the test was set for July 16th 1945.
Different engineering divisions had to estimate how much plutonium to use, and that the bomb wouldn't explode prematurely. The chemical-metallurgical division converted the plutonium into metallic plutonium. The X division developed a spherical implosion charger, so that the implosions resulted in a convergent detonation wave propagation. 
The explosion site was a remote area of army land, about 320 kilometers south of Los Alamos, in a place named Jornada del Muerto - the "day's journey of death."  Scientists and soldiers gathered at 3 different observation points about 9 kilometers away from the explosion zone. One of the observation points was the control center, where scientists directed operations, triggered the bomb and watched the explosion. 
© Dennis Chang. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
 E. Segrè, Enrico Fermi: Physicist (University of Chicago Press, 1970), p. 144.
 S. U. Newtan, Nuclear War I and Other Major Disasters of the 20th Century (AuthorHouse, 2007).
 S. Crewe and D. Anderson, The Atom Bomb Project (Gareth Stevens Publishing, 2004).