Recipient of the Nobel Prize in physics. He received international professional recognition after being awarded the 1938 Nobel Prize in Physics, according to the Nobel Prize committee, for: of "his demonstrations of the existence of new radioactive elements produced by neutron irradiation, and for his related discovery of nuclear reactions brought about by slow neutrons." Since 1935, he received 38 nominations for the Nobel candidacy. In 1934, Fermi and his colleagues discovered that when neutrons are slowed down, the interaction rate with nuclei increases. This revelation led to the discovery of many hitherto-unknown radioactive isotopes. He was the first to split the atom, designed the first atomic piles, and produced the first sustained nuclear chain reaction. Born the oldest son of Alberto Fermi, Chief Inspector for the Ministry of Communications, and Ida de Gattis, his early aptitude for math and physics was quickly recognized and encouraged. Fermi studied at the University of Rome and received a doctor's degree in physics from the University of Pisa in 1922. His entrance exam for the University of Pisa required an essay, for which 17-year-old Fermi submitted the derivation and solution of the Fourier analysis of partial differential equations for waves on a string; the evaluator immediately marked the essay as fit for a thesis for a doctoral degree award. After winning grants to study physics for the next two years, he became a Professor of mathematical physics and mechanics at the University of Florence in 1924. Two years later, he became a professor of theoretical physics at the University of Rome, where he became interested in the structure of the atom, and began to devise experiments to help him understand atomic structure. In 1928, he married Laura Capon; they would have a son, Giulio, and a daughter, Nella. For recreation, he enjoyed walking, mountaineering, and winter sports. In 1934, he began to bombard various elements with neutrons, producing radioactive atoms. In these experiments, he initially thought he had discovered elements beyond uranium, but later discovered he had actually split the atom. When physicists, Lise Meitner and her nephew Otto Frisch repeated his experiments and showed that he had actually split an atom, creating the process of nuclear fission, which at the time, nuclear fission had been considered theoretically impossible. Fermi's research on nuclear reactions awarded him the 1938 Nobel Prize in Physics. After receiving his Nobel Prize in Stockholm, Fermi and his family immigrated to the United States in 1938 because of his dislike of Italian fascism, and in part due to the anti-Jewish policies adopted by the Mussolini government. Enrico Fermi died of stomach cancer at age 53 in 1954.