Segre was an Italian physicist and Nobel laureate who discovered the element technetium and astatine and the antiproton and a sub-atomic antiparticle. All of these elements helped discover what would cause the atomic fusion and make that blast it did. He was a group leader in the Manhattan Project. He became the head of the labratory's P-5 Group which formed part of Robert Bacher's P division. His group set up the equiptment that they used in the disused Forest Services cabin in the Pajarito Canyon which is close by Los Alamos. Segre's main goal was it measure and catalog the radioactivity of various fission products. That most important components was determining the degree of isotope enrichment achieved with carious samples of enriched uranium. The group ended up measuring the activity of thorium, uranium-234, uranium-235 and uranium-238. In the end the group ended up finding out that the increased activity was due to plutonium-240. In 1944 Segre was directed to Oppenheimer's office. Segre was later given the role to designate R-4 and was supposed to measure the gamma radiation from the Trinity nuclear test. The blast was so huge that it damaged and destroyed most of the experiment.