Fermi now traveled the country visiting sites crucial to the war effortin Hanford, Oak Ridge, Argonne, and Los Alamos. He now merited a constant bodyguard, John Baudino, and the codename "Mr. Farmer." In the summer of 1944, the Fermi family moved from Chicago to Los Alamos. They remained there until December 31, 1945.
July 16, 1945, was the date of the first atomic bomb test at Trinity in the New Mexico desert. Fermi observed it from the base camp some 10 miles from the blast site. He described having a wide board with a dark welding glass insert to protect his face and feeling the heat sensation on exposed parts of his body.
Ever the scientist, Fermi wondered about the strength of the blast. He described the simple test he made:
"About 40 seconds after the explosion the air blast reached me. I tried to estimate its strength by dropping from about six feet small pieces of paper before, during, and after the passage of the blast wave. Since, at the time, there was no wind I could observe very distinctly and actually measure the displacement of the pieces of paper that were in the process of falling while the blast was passing. The shift was about 2.5 meters, which, at the time, I estimated to correspond to the blast that would be produced by ten thousand tons of T.N.T."1
Following the blast, Fermi examined the 800 ft. diameter crater from the safety of a lead-lined Sherman tank, noting the glazed desert surfacethe sand had melted and re-solidified.
1. U.S. National Archives, Record Group 227, OSRD-S1 Committee, Box 82 folder 6, "Trinity."