Enrico Fermi: The Man Who Gave the World Nuclear Fission
Enrico Fermi, through his labors, gave the world the first prototype nuclear reactor and also contributed immensely to the development of the first atomic bomb. Both of these technologies have proved to be both great benefits and incredibly destructive weapons to our modern world.
Ethics and morality of nuclear power and weapons aside, his contributions helped change the world forever, for better or worse.
Enrico Fermi was born in Italy in 1901 and his early research was in general relativity and quantum mechanics. He would quickly appreciate the potential for nuclear physics and dedicate his life to it.
Enrico's achievements would win him the Nobel Prize in 1938, an event that was both an honor and a literal lifesaver. He would later build the first nuclear reactor and work on the Manhattan Project. Fermi would end his days at home in Chicago in 1954.
Enrico Fermi was even honored on the periodic table with element 100, Fermium, taking his name.
We do hope this short biography of Enrico Fermi will do the man justice.
Enrico Fermi was born in Italy on September the 29th, 1901 in Rome. Enrico was the third child of Alberto and Ida de Gattis Fermi. His mother, Ida, was a remarkable woman in her own right. Trained as a teacher, she was highly intelligent and played a major role in the education of her children.
His father, Alberto, was the Chief Inspector of the Ministry of Communications for the Italian Government.
Enrico Fermi attended a local grammar school and he quickly showed an aptitude for mathematics and physics. This talent was nurtured and developed by his father's colleagues, among whom included A. Amidei.
At the very young age of 14, Enrico Fermi's eldest brother tragically died suddenly. Enrico was very close to his brother and was devastated by the event, and this is said to be a major factor in his interest in physics.
His parents, noticing Fermi's intense emotional pain encouraged him to focus on his studies. He, quite by chance, came across a couple of physics books written half a century earlier and was completely enthralled.
During his formative teenage years, Enrico and his friends conducted various physics experiments just for fun. These included testing the density of Rome's water supply, as you do.
From undergraduate to doctor: Enrico Fermi's studies
Fermi won a scholarship to the very prestigious Scuola Normale Superiore University in Pisa, Italy in 1918. In fact, so impressive was his entry essay that he was fast-tracked to the doctoral program under Professor Puccianti. Fermi graduated with honors in 1922.
The following year, in 1923, he even won a Rockefeller Fellowship that granted him several months with the renowned physicist Max Born in Gottingen, Germany.
Having successfully being awarded a Rockefeller Fellowship, Fermi moved to Leyden to work with P. Ehrenfest in 1924. He would subsequently return to Italy between 1924 and 1926 to take up a post as a lecturer in Mathematical Physics and Mechanics at the University of Florence.
In 1926, Enrico Fermi discovered the statistical laws governing particles subject to Pauli's exclusion principle. These laws are now known as Fermi statistics.
These particles are now known as fermions which contrast with bosons that obey the Bose-Einstein statistics.
Fermi was elected Professor of Theoretical Physics at the University of Rome in 1927. He maintained this post for just over a decade before global political events would dramatically change his life forever.
Enrico Fermi and the Beta particle decay theory
Enrico Fermi's early career in Italy saw him mainly occupying himself with electrodynamics problems. He also pursued theoretical investigations on various spectroscopic phenomena.
At some point in his tenure, Fermi would significantly change his life forever by shifting his focus from the outer electrons to the atom's nucleus.
Given his achievements to date, it should come as no surprise that Enrico Fermi's career in physics and personal life flourished. He was soon married to Laura Capon in 1928. She was the daughter of a respected Jewish family in Rome.
Fermi's most important work was about to begin. At this time, he evolved the Beta particle decay theory.
This would coalesce previous work on radiation with Pauli's concept of the neutrino. Following on from the discovery by Curie and Joliot of artificial radioactivity in 1934, Fermi demonstrated that nuclear transformation could occur in nearly every element.
This very important work would result in the discovery of slow neutrons that same year. This would rapidly lead to the discovery of nuclear fission and the production of elements that lie beyond the existing periodic table.
One of the atoms Enrico Fermi succeeded in splitting was the seemingly innocuous Uranium. This work would ultimately lead to the discovery of slowing down neutrons which were the precursor to the advent of nuclear fission.
By 1938, Enrico Fermi, was, without doubt, the greatest expert on neutrons.
The Nobel Prize helps Enrico Fermi escape to America
His findings and achievements ultimately led to Enrico Fermi winning the 1938 Nobel Prize in Physics "for his work with artificial radioactivity produced by neutrons, and for nuclear reactions brought about by slow neutrons".
As it turned out this was not only a great honor but would ultimately save Fermi and his family's life. The specter of fascism had just infected Italy and anti-Semitism was openly flaunted.
The ceremony was held in Stockholm, Sweden which gave Fermi's a perfect excuse to leave Italy and have the freedom to escape to America.
Enrico Fermi's American Dream in Chicago
Once safely in the United States, Fermi was appointed the professor of physics at New York's Columbia University in 1939. His work here led to one of the greatest and most destructive discoveries in man's history.
Hahn and Strassmann had discovered the phenomena of nuclear fission in the early part of 1939. This discovery was immediately appreciated by Fermi who understood the possibility of the emission of secondary neutrons and, perhaps, a chain reaction.
Whilst at Columbia University, Enrico Fermi found that if Uranium neutrons were emitted into another sample of fissioning Uranium, they could further split those atoms and set off a chain reaction. Not only does this sound impressive, but it also happened to unleash enormous amounts of energy.
Enrico's experiments led to the very first controlled nuclear chain reaction in Chicago on the 3rd of December 1942. This actually happened underneath Chicago's athletic stadium on a squash court of all things (is that ironic, we're not sure?).
Of course, at this time the world was plunged into one of the most destructive events in human history, the Second World War.
His work had not gone unnoticed and he was quickly recruited into the Manhattan Project. As we all know today, this project's primary objective was to harness the power of the atom to produce an incredibly powerful weapon of war.
Fermi and his wife also cemented their commitment to the country that had sheltered them by officially becoming citizens in 1944.
Enrico Fermi opposes and condemns the H-Bomb
After the conclusion of the war, Enrico Fermi was appointed to the General Advisory Committee for the Atomic Energy Commission. In October of 1949, the commission met to discuss the feasibility of ramping up the power of the recently completed atomic bombs that were unleashed on Japan.
The proposal for developing Hydrogen bombs appalled Fermi, a stance he stubbornly stood by. He co-authored a scathing addendum to the committee's report that condemned the H-bomb in no uncertain terms.
President Harry S. Truman ordered the development of the bomb regardless and ignored Enrico Fermi's warnings.
Fermi would later return to Los Alamos, New Mexico to help with the calculations in the hope that he could prove the superbomb would be impractical.
As history tells us, clearly he was unsuccessful.
The Chicago Pile-1 nuclear reaction underneath a field
Chicago Pile-1 (CP-1) was the world's first artificial nuclear reactor. The reactor was built underneath the west stand of the Stagg Field in an abandoned squash court. Stagg field was a football stadium for the University of Chicago. By all accounts, the stand was redundant at the time of the test.
Enrico Fermi would later describe the apparatus as "a crude pile of black bricks and wooden timbers". Well, that certainly fills us with confidence.
The reactor's assembly began in November of 1942 under the direct supervision of Fermi. Of course, such an undertaking could not be completed by one man alone. Fermi's team included Herbert L. Anderson, Walter Zinn, Martin D. Whitaker, and George Weil.
The basic, almost Jerry-Rigged apparatus was built around 45,000 graphite blocks and wood, weighing a total of 360 tons. This was to act as the reactor's neutron moderator.
Uranium oxide, or powder, was formed into "hockey puck" pieces and inserted into the blocks.
These uranium oxide "puck" blocks were arranged in a dictated pattern by Enrico Fermi and other project coordinators as seen fit. A control rod was also included to control the reaction as modern control rods do in current reactors.
Chicago Pile-1's construction
Unlike subsequent reactors, Chicago Pile-1 lacked significant radiation shielding or even cooling systems. This was not an oversight, however, the reactor was only run at low power (around half a watt).
The entire structure had been intended to be roughly spherical in shape but as work proceeded this was altered.
Fermi had calculated that the chain reaction's critical mass could be achieved without necessarily completing the structure as planned.
CP-1 would later be moved to Red Gate Woods in 1943 and reconfigured to become designated as Chicago Pile-2. This reactor was actually operated right up until 1954 when it was finally decommissioned and buried.
The Stagg Field stands were later demolished in August of 1957 with the site becoming designated as a US National Historic Landmark as well as a Chicago Landmark.
How did the Chicago Pile-1 work?
The pile was a composite of graphite blocks and a wooden "cradle" structure on the outside. The Uranium/Graphite blocks were arranged in a roughly spherical structure to attempt to maximize the chances of "criticality" for the reaction.
On the 2nd December, tests began. George Well was placed in charge of operating the control rod for the experiment. His role should not be underestimated.
Any wrong movement and the reaction could have gone critical and seriously ruined a lot of peoples lives.
The control rod was effectively a meter stick with a piece of Cadmium on top, crude but effective.
The test began in the morning to lunchtime, with Enrico Fermi dictating to Well to pull out the rods. Neutron levels would then be monitored to see the "reaction" of the reactor.
As you might expect, the level would rise dramatically and then level off.
This would be an indication of the "closeness" to criticality needed for self-sustaining nuclear fission.
Observers would later note that they would get a little nervous by how close the readings would come to criticality. Tensions were mounting until Fermi declared that the experiment should be halted for lunch.
Experiments would then continue, further "pushing their luck" until Fermi declared the experiment halted.
“There was Fermi’s face—one saw in him no sign of elation. The experiment had worked just as he had expected, and that was that. Cool and collected—Fermi’s face was that of a competent man of action busily engaged on the one important job.” - Arthur Compton.
The entire event was celebrated with a single bottle of Chianti and some paper cups, oh and a lot of clapping and toasting. A rather civilized celebration given the magnitude of the event. That must have been an interesting experiment to observe.
Enrico Fermi's role in the Manhattan Project
"The person that really impresses me most among all the people that I met there was Fermi. He was really an extraordinary man. He happened to be a physicist, but I think he could have gone into any profession, whether by accident or by design and done extraordinarily well at it." – Crawford Greenewalt
Chicago Pile-1 served a dual purpose, once the team discovered that "criticality" was indeed practical the technology's potential energy source was obvious.
But the project's real intention was in fact to weaponize the atom.
In this role, the findings of the Chicago series of experiments would ultimately form a critical component of the famous Manhattan Project.
The Manhattan Project was, in effect, a dream team of scientific luminaries at the time. Enrico Fermi was by all accounts, one of the most distinguished. His successes to date, including the Chicago Pile series of experiments, cemented his place on the team and into history.
Fermi was personally involved in many of the pivotal milestones throughout the project. He was specifically involved in proving the concept of fission and was an important contributor when the X-10 Graphite Reactor and B Reactor achieved criticality.
He was also heavily involved in the Trinity test.
Enrico Fermi's influence and his colleagues
Fermi was a distinguished teacher and master of both theoretical and experimental physics, as we have seen. He was even nicknamed "The Pope".
After the massive accomplishments made in Chicago, Oppenheimer himself formally recruited Fermi onto the Manhattan Project. Enrico Fermi became the associate director of the laboratory at Los Alamos in 1944.
Fermi personally inserted the first Uranium fuel slug into the ill-fated B Reactor at Hanford. Working with John Wheeler, Fermi helped determine that xenon poisoning was responsible for the mysterious shutdown of the reactor.
Fermi not only played a vital role during the project but made a massive impression on his colleagues. Amongst others, Leona Marshall Libby, a close friend of his, would later recall:-
“He was a marvelously wise director of scientific effort in the sense that he knew exactly where to be careful, and he could very frequently guess when it was unnecessary to make more accurate measurements. He had a very good sense of the degree of effort that would give the required result without wasting it,”
Fermi's published works
Enrico Fermi penned numerous papers in both theoretical and experimental physics. Fermi's more important contributions to physics include the following:-
-"Sulla quantizzazione del gas perfetto monoatomico", Rend. Accad. Naz. Lincei, 1935 (also in Z. Phys., 1936), concerning the foundations of the statistics of the electronic gas and of the gases made of particles that obey the Pauli Principle.
- Several papers published in Rend. Accad. Naz. Lincei, 1927-28, deal with the statistical model of the atom (Thomas-Fermi atom model) and give a semiquantitative method for the calculation of atomic properties. A resumé of this work was published by Fermi in the volume: Quantentheorie und Chemie, edited by H. Falkenhagen, Leipzig, 1928.
-"Uber die magnetischen Momente der AtomKerne", Z. Phys., 1930, is a quantitative theory of the hyperfine structures of spectrum lines. The magnetic moments of some nuclei are deduced therefrom.
-"Tentativo di una teoria dei raggi ß", Ricerca Scientifica, 1933 (also Z. Phys., 1934) proposes a theory of the emission of ß-rays, based on the hypothesis, first proposed by Pauli, of the existence of the neutrino.
Fermi's Final years, his death and legacy
Enrico Fermi continued his work at the Institute of Nuclear Studies at Chicago University in his later years. He turned his attention to high-energy physics and led investigations into the origins of cosmic rays and theories on the fantastic energies present in cosmic ray particles.
These theories revolved around the idea of a universal magnetic field, that acted as a giant accelerator, that would account for the fantastic energies present in the cosmic ray particles.
Enrico Fermi was a member of several academies and "learned" societies in Italy and overseas during his life. One of which was the Royal Academy of Italy in 1929.
He was, in fact, one of the very first 30 members of the Royal Academy. Quite an honor.
Fermi was always in great demand as a lecturer throughout his lifetime. He was given several courses at the University of Michigan Ann Arbor and Stanford University.
Enrico Fermi was the first recipient of the special $50,000 award, which now bears his name, for work on the atom.
In his later years, Enrico Fermi would develop incurable stomach cancer and would spend his last few months in Chicago undergoing medical treatment.
Enrico Fermi, the man who helped give the world the Nuclear Reactor and Atomic Bomb died in his sleep on November the 28th 1954.
He was at home in Chicago, Illinois.
Enrico Fermi and his wife Laura had one son Giulio and one daughter Nella.
Apparently, his favorite pastimes, when not playing with atoms, was walking, mountaineering, and winter sports.