New York. The basement of Schermerhorn Hall. The first Fermi pile begins to take shape. Local Columbia football players are called in to move the graphite blocks and heavy tanks of uranium oxide. It is 2.5 meters long and 3.3 meters high, with 288 tanks of uranium oxide, slits with rhodium foils to measure radioactivity, and a neutron source at the base in a layer of paraffin. The experiment’s results are disappointing: even with such a pile of infinite size, Fermi calculates, the threshold for reaching criticality would still be 13%. But they are not discouraged. They decide to continue in Chicago, under the aegis of MetLab (Metallurgical Laboratory of the University of Chicago). But Fermi, while awaiting the date of his transfer to Chicago, wastes no time and manages to build another pile, this time with 2,160 sintered pellets of uranium oxide powder, with a higher concentration and weighing 2 kg each. The pellets have a diameter of 8 cm and the same height. To remove as much air as possible (which can absorb neutrons), a cubic tin “can” is constructed around the pile, approximately 3 meters on each side. The air is pumped out and replaced with carbon dioxide. The results improve by 4%. A couple of accidents also occur. In the first, Zinn, while opening a can of thorium, explodes in his face upon contact with the air, and despite wearing protective glasses and gloves, he suffers burns to his hands. In the second, more serious, accident, Anderson, Pergram, and Fermi receive a shipment of radium and beryllium to prepare a neutron source. But the sample is damp, so they place it on a stove to dry it and leave. Upon returning, the powder had caught fire. Anderson rushed to put out the fire, but inhaled some beryllium dust, which caused beryllium disease, which would ultimately kill him many years later, at the age of 74. In April 1942, the battery was dismantled and shipped to Chicago.
