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Fermi’s Students and Collaborators

Fermi’s Students and Collaborators

He graduated in Rome in 1921 under the guidance of Corbino, and he was an assistant at the Institute of Physics until 1927. In 1924, he was named free lecturer, and the following year he spent a long period of study in Cambridge, where he came into contact with Eddington and Dirac.

In Rome, he carried out pioneering research on the theory of highly ionized gases, inspired respectively by the newly published ideas of Schrödinger and by his relationship with Eddington.

In 1926 he arrived at the Institute of Physics of Arcetri, as the chair of theoretical physics: He was second, behind Fermi, in the winning trio of the first competition launched in Italy.

Here, in addition to continuing his Rome-based research, he played a fundamental role as a teacher, contributing decisively to the dissemination of the new ideas of quantum mechanics and to the training of an entire generation of young researchers.

In 1930, he moved to Turin, and here too he created an important school of modern theoretical physics.

In 1947, he accepted the proposal of the Laval University in Québec, Canada, to fill the chair vacated by Rasetti, and for three years he dealt with various theoretical topics, including the study of β-ray spectrometers.

In 1950, he returned to Italy, to Rome, as the chair of higher physics, and in 1958 he moved to the chair of theoretical physics.

Soon all of his activities were absorbed by the electrosynchrotron project that INFN, in 1953, had decided to build within the new Frascati National Laboratory. Persico was in charge of the direction of the theoretical section of the synchrotron group.

In 1958, he returned to his former interests in highly ionized gas physics and also became interested in the theoretical aspects of nuclear reactor physics.

He died in Rome on 17 June 1969.

 

Emilio Segrè was born in Tivoli in 1905 into a wealthy Jewish family. Having begun engineering studies and after meeting Fermi in 1927, he moved on to physics, a discipline that had always fascinated him.

He graduated in 1928 under Fermi’s supervision. In 1929, he obtained his first assignment at the University of Rome as assistant to Professor Corbino; after a period of specialization in Germany, with Professor Otto Stern, he returned to Italy, and in 1932 he obtained the post of professor at the University of Rome where he continued his close collaboration with the Fermi group. After some spectroscopic work, he devoted himself to atomic physics: In fact, starting from 1934, he began to take part in the experiments on artificial radioactivity induced by neutrons that had started at the Physics Institute under the supervision of Fermi. Segrè, among the ‘boys of via Panisperna’, was nicknamed ‘the basilisk’:

In 1935, he won the Chair of Experimental Physics at the University of Palermo, where he remained until 1938 when, due to racial laws, he moved permanently to the USA, acquiring US citizenship in 1944. He participated in the Los Alamos Manhattan Project. His subsequent research focused mainly on issues relating to nuclear structures and interactions between particles.

In 1959, he was awarded the Nobel Prize for the discovery of the antiproton, together with Owen Chamberlain.

In 1974, he took up the Chair of Nuclear Physics at the University of Rome.

Born in Carpaneto, near Piacenza, he spent his childhood in Modena, and, in 1919, he moved with his family to Padua, where his father Ugo had been called to the chair of higher geometry. In 1924 the Amaldis moved to Rome, where their father obtained a professorship.

After completing his high school studies, in 1926, he enrolled in the Faculty of Engineering. He switched to physics the following year and graduated in 1929 with a thesis on the Raman effect: His supervisor was Franco Rasetti.

Corbino’s assistant in the years 1931–1936, he was promoted to the assistant position in 1936. The following year, he won a chair in Cagliari, but on Corbino’s death, also in 1937, he was called to succeed him in the chair of experimental physics.

In 1935, he and Fermi were the only ones to continue working together regularly, until December 1938, when Fermi left Italy for good.

During and after the war, Amaldi continued the work begun by Corbino, consolidating and developing the so-called “school of Rome”. After the war, he became one of the major promoters of the rebirth of science in Italy and Europe.

A protagonist of the constitution of the National Institute of Nuclear Physics and of the first National Laboratory, erected in Frascati, in the early 1950s he was among the founding fathers of CERN: He had the delicate role of Secretary General of the provisional organization, leading it up to the signing of the Constitutive Treaty of 1954.

He also had an important and pioneering role in launching the idea of ​​a European center for space research: ESA’s third automatic vehicle, the ATV-3, which took off on March 28, 2012 to transport supplies to the International Space Station, was named Edoardo Amaldi in his honor.

He was born in Catania in 1906 into an influential family of the Sicilian liberal bourgeoisie. Grandson of the physicist Quirino and son of the engineer Fabio Massimo, Ettore showed from childhood an extraordinary talent for mathematics and a formidable ability to calculate.

In 1923, he enrolled at the University of Rome, at the Faculty of Engineering; transferring to physics in 1928, he graduated in 1929.

While still a student, he began to attend Fermi’s informal seminars at the institute, and after graduating he continued to attend the institute ‘freely’, that is, without receiving a salary.

Right from the start, he attracted the admiration of Fermi, who considered him a first-rate theoretical physicist.

In 1933, he spent a period in Leipzig to devote himself to research on the structure of atomic nuclei and on the relativistic formulation of quantum mechanics. Here he established a relationship of collaboration and friendship with Werner Heisenberg. The formulation of the Heisenberg–Majorana theory of the nucleus dates back to this period.

Upon his return to Italy, he stopped attending the institute in via Panisperna.

In 1937, he was called to the chair of theoretical physics at the University of Naples “for his high reputation for singular expertise”: He took up service on 16 November 1937 and held the first part of the course, until his mysterious death, which took place on 27 March 1938. His disappearance has been the subject of countless hypotheses and investigations over the years that has fueled one of the most talked about detective stories of all time.

Majorana did not publish many works, but these were of such a high and innovative value that they are still of great scientific relevance.

A contemporary of Fermi and Rasetti, Oscar D’Agostino was born in Avellino.

Graduated in 1926, he became a volunteer assistant at the Institute of Chemistry of the University of Rome.

In 1927, he obtained the qualification to exercise the profession of chemist and, starting from 1931, he resumed his activity as an assistant at the University of Rome, continuing starting in 1933 as a CNR scholar, a position obtained on the initiative of Corbino and Stop.

In 1934, after spending a period at the Institut du Radium in Paris, where he deepened his knowledge in the field of radioisotopes, he returned to Rome to collaborate with the group of physicists led by Fermi.

He contributed to the research on radioactivity induced by slow neutrons, signing with the other boys of Via Panisperna the fundamental works published in 1934 and 1935.

In 1936, having finished his work with the Fermi group, he was hired by the then nascent National Institute of Chemistry of the CNR. In 1938, he was declared a free lecturer in general and inorganic chemistry and won the competition for assistant at the Physics Laboratory of the Higher Institute of Health.

In 1940, he moved to the National Institute of Chemistry of the CNR in the role of department head.

In 1945, he returned to the National Institute of Health, in the physics laboratory, as assistant. In 1949, promoted to inspector general, he established the radiochemistry department of the institute, specifically oriented towards the use of radioisotopes in biochemical research. In 1959, he engaged in the complex regulatory work of the Advisory Commission for Explosive and Flammable Substances at the Ministry of the Interior, which he joined in 1948. He retired in 1966.

Bruno Pontecorvo was born on August 22, 1913, in the small village of Marina di Pisa. The family, of Jewish faith, belongs to the rich class, but their natural predisposition to genius is the real treasure. Guido, Bruno’s older brother, will become an internationally renowned geneticist; Gillo, the younger one, will choose a cinematographic career, winning a Golden Lion for the film “The Battle of Algiers” and being nominated for two Oscars in 1969 for the same film.

When he was only 16 years old, he graduated from the Liceo Classico “Galileo Galilei” in Pisa and decided to enroll in the Faculty of Engineering, where he successfully passed the two-year course. But Bruno does not like drawing and decides to move to physics. Guido supports his decision, but on one condition: he must move to Rome because there are Enrico Fermi and Franco Rasetti. He brilliantly passed the test and graduated with honors in 1933, at only 20 years old, officially entering the group of the Boys of Via Panisperna with the affectionate nickname of “Cucciolo”. However, Pontecorvo would not appear in the famous photo that depicts the five Boys but, later, he would admit: “They often ask me where I am. I took the picture!”.

In 1936 he won a scholarship for a 6-month stay abroad and, on Fermi’s advice, he chose to go to the Institut du Radium in Paris, to work with the new Nobel Prize winners Frédéric and Irène Joliot-Curie. In this period matures in him a strong political ideal, also fed by Frédéric (who belonged to the French Resistance) and his cousin Emilio Sereni (exiled anti-fascist and future parliamentarian with the Italian Communist Party). In the meantime, the Second World War broke out and Bruno could not return to Italy, both because he was Jewish and because of his political ideals, and on June 13, 1940, with the Nazis besieging Paris, he fled to the United States. Thanks to Segré and Fermi, who had already settled there for a year, he found a job for an oil company.

Based on the technique of neutron slowing assimilated in Rome, he developed an ingenious technique for the detection of oil wells, the so-called “neutron coring”. In the years of the Second War, the United States begin the arms race inaugurating the Manhattan Project but Pontecorvo, probably for his pro-communist ideas, is not enlisted. Instead, he was called to Canada to work in the Chalk River laboratory. During the war period his major commitment concerns the construction of the heavy water nuclear reactor and all the problems related to its design.

Between 1944/45, Conversi, Pancini and Piccioni carried out the famous experiment in Rome in which they identified a new particle, about two hundred times heavier than the electron, the muon. This particle has as decay product only an electron, which did not have a well defined energy but it was assorted in a continuous interval; this meant that muon split in an electron and, at least, in other two neutral particles, invisible to instrumentation.

Pontecorvo deduced that the capture of the muon by the atomic nucleus, just like the capture of the electron, produces neutrinos (the mysterious particle predicted in the thirties by Wolfgang Pauli to explain the spectrum of β decay). He discovered that the weak interaction, discovered by Fermi, has a much more general character than previously thought. He also hypothesized that these two neutrinos were of different nature: one bound to the primary muon, the other bound to the electron. Pontecorvo became one of the world’s leading experts on neutrino physics.

In 1950 he decided to go beyond Iron Curtain and arrive in Soviet Union. The news arouse a great clamor and Italian newspapers headlined “Escape to Moscow of an atomic scientist”, advancing the hypothesis (completely unfounded) that Pontecorvo has brought as a gift to Stalin his skills, and his secrets, to build the atomic bomb. For five years no one has news of him. Only in February 1955 appears his first statement on Pravda, the press organ of the Soviet Party.

Meanwhile Bruno has moved to Dubna, the famous atomic city. His fame as a former student of Fermi and his genius precede him: everyone is excited to work with him. He is put in charge of the experimental physics division of the Laboratory of Nuclear Problems, where some of his brightest ideas begin to take shape. In 1959 he published a paper (Electronic and muon neutrinos) where he hypothesized the existence of three types of neutrinos whose properties are detectable. High energy neutrino physics was born.

The Dubna accelerator, although it was the largest of the time, did not reach energies high enough to prove his hypothesis. Only a few years later (early seventies), the Americans Ledermann, Schwartz and Steinberger experimentally confirmed the theory of the Italian physicist. The three won the Nobel Prize in Physics in 1988 “for the neutrino beam method and the demonstration of the double structure of leptons through the discovery of the muon neutrino.” Pontecorvo was the first to make the prediction but was excluded from receiving the prize.

Between 1957 and 1967 Pontecorvo worked on the theory of lepton mixing. Leptons are elementary particles divided into three families: electrons, muons and tauons. To each of this family is associated a neutrino of different nature (the electron neutrino νe and the muon neutrino νμ and the third, the tauon neutrino ντ was theorized in the seventies and experimentally observed in 2000). The theory developed by Pontecorvo states that different neutrinos in vacuum can transform into each other. This phenomenon is called neutrino oscillation. A remarkable and important consequence of this theory is that neutrinos have mass. This theoretical prediction was verified for the first time for solar neutrinos in 1968 and then confirmed in 2010 by experiments performed in the Laboratories of the National Institute of Nuclear Physics of Gran Sasso.

Only in 1978 Pontecorvo returned to Italy, on the occasion of the seventieth birthday of Edoardo Amaldi. The first symptoms of Parkinson’s disease already appeared, but it never deprived him of mental lucidity. During one of his last interviews, when asked if he regretted his choice to go to USSR, Pontecorvo replied:

“I thought about it a lot but I can’t give an answer. I think I have always been a good person, even if sometimes I may have made wrong choices. But what is more important, making the right choices or being a good person?”.

Bruno died in Dubna on September 24, 1993. Thanks to his brilliant insights, and his methods of investigation, no less than four Nobel Prizes have been awarded (1988, 1995, 2002, 2015).

Franco was born in Pozzuolo Umbro on 10 August 1901. His father, Giovanni Emilio, was the holder of the itinerant chair (a sort of itinerant teaching mostly addressed to landowners) of Agriculture at the University of Pisa and was specialized in chemistry, botany and entomology (the study of insects).

Rasetti had been interested in entomology since he was a child, enriching his father’s already rich collection and together they published an article in 1919 in a specialized bulletin. His uncle Gino, professor of pathology, also played a fundamental role in his scientific maturation:

“To the influence of my parents I must add that of my uncle, Gino Galeotti, a professor of pathology who was very well known in Italian universities. He could solve differential equations, discuss the first Christian heresies, read Tolstoy in Russian. To these talents he added an enthusiastic passion for mountain climbing and skiing that I did not hesitate to follow.”

His vacations, made up of climbing and walking in the mountains, together with Enrico Fermi and the other boys from via Panisperna will be famous.

Rasetti did not attend elementary school because he was a precocious child: when he was seven, he could distinguish the main families of insects and knew hundreds of scientific names by heart. After obtaining his high school diploma, taking seven in physics and chemistry, he was admitted to engineering at the University of Pisa in 1918. There he met Enrico Fermi, and a deep friendship immediately developed between the two.

“In the winter of 1918 I met Enrico. We became close friends and I learned much more physics from him than from the professors. It was undoubtedly through his influence that in my third year I decided to drop engineering and become a physics major.”

After completing the two-year degree, he switched to physics, where only three students were enrolled. In Pisa there is Luigi Puccianti, director of the physics laboratory, who gives great freedom to the students by providing all the materials and leaving them the keys to access the libraries and laboratories. Franco was guided by Puccianti in the field of spectroscopy, a discipline that deals with the study of spectra of electromagnetic radiation, and graduated with honors in 1922 with a thesis entitled “Anomalous dispersion in the vapors of alkali metals.

After a brief period in Florence, Rasetti was called by Orso Mario Corbino to the Institute of Physics in Rome where Fermi had obtained one of the first three chairs of theoretical physics in Italy. In 1928 he spent a year at the California Institute of Technology, specializing in the recently discovered Raman effect.

In 1930 he won the competition for a chair in experimental physics and was called once again by Corbino in Rome to be able to Fermi. Only a year later he won a scholarship to go to Germany, where he collaborated with Lise Meitner and Otto Hahn on some methods of preparation of radioactive sources and their detection. A few years later Meitner and Hahn will be protagonists, respectively, of the theoretical and experimental explanation of nuclear fission.

It was in Rome that Rasetti exploited all the experience accumulated in the study of nucleus physics, together with the boys from via Panisperna. If Fermi was known as “the Pope”, Rasetti was nicknamed “the Cardinal”. He was, to all intents and purposes, his right-hand man and a key figure in the Institute of Physics. It was the two of them who took care of most of the measurements and calculations, while Segré prepared the samples to be irradiated and collaborated in the chemical analysis, Amaldi built, and above all operated, the Geiger counters and all the instrumentation.

After the promulgation of racial laws, Rasetti decided to emigrate and accepted a position at the University of Quebec, Canada, building from scratch a laboratory of nuclear physics and cosmic rays, where in ’41 he was able to measure the average life, or the time it takes a particle to “transform” into a different object (decay) of muons. But it was in September ’42 that Franco made a decisive choice: he refused to collaborate with British scientists, who had moved from Great Britain to Montreal, on the project to develop nuclear energy for military purposes (a project that would later merge into the more famous Manhattan Project of Los Almos). It is Franco himself who explains why:

“After deep reflection I declined the offer. I was convinced that nothing good could come from new and more monstrous means of destruction and subsequent events have confirmed my suspicions. As perverse as the Axis powers were, it was evident that the other source was sinking to a similar moral (or immoral) level given their conduct, as evidenced by the massacre of thousands of Japanese civilians in Hiroshima and Nagasaki”.

From the post-war period onwards, Rasetti deals exclusively with botany and paleontology, accepting a professorship at Johns Hopkins University in Baltimore, where he remained for over twenty years. At the same time he developed a passion for naturalistic photography, combined with that for the mountains and mountaineering, which never abandoned him. At the end of his biography he wrote:

“I am well aware that geology and paleontology do not have the high rank of physics in the hierarchy of the creations of the human intellect. I appreciate the supreme aesthetic value of general relativity and quantum mechanics, and I admire the human minds that have succeeded in expressing an infinity of phenomena in a few elegant mathematical equations. Instead, to reconstruct the history of the earth and the evolution of life, an immense mass of patient observations is needed. For me, however, the contemplation of the wonders of nature, a mountain, a flower, an insect, a fossil, did not give me less pleasure than admiring the creations of our physical and mathematical mind.

He died, at the age of 100 years, on December 5 in 2001.

Giuseppe Occhialini, affectionately known as Beppo, was born in Fossombrone on 5 December 1907 and was the son of an artist: his father, Raffaele Augusto, was a physicist known for his studies in the field of optics and for having been the author of several treatises on radioactivity.

Beppo graduated from the University of Florence in 1929 with a thesis on cosmic rays, energetic particles from extraterrestrial space, under the guidance of Bruno Rossi, only two years older.

In 1931, thanks to a scholarship of three months of the National Research Council (CNR), he left for Cambridge to work with Patrick Blackett at the prestigious Cavendish Laboratory, which was directed by Lord Ernest Rutherford. In England, he began to learn the technique of the Wilson Chamber, or fog chamber, which is a particular instrument for the detection of elementary particles. Together with Blackett, Occhialini modified the fog chamber using techniques he had learned in Florence from Bruno Rossi. A counter was connected to the chamber, which was controlled by a particular electric circuit, which would be triggered when beams of particles passed through it.

Their collaboration is immediately fruitful. Together they discovered, sometime after Carl Anderson that in USA was performing the same measures, the electron-positron pairs. Besides confirming the existence of electron antiparticle, these measurements provided the first proof of the existence of antimatter, predicted by Paul Dirac some years before.

Patrick Blackett will receive the Nobel Prize in 1948 “for his development of Wilson’s fog chamber method and for his discoveries in the field of nuclear physics and cosmic radiation”. Occhialini is the big loser from the awards.

Beppo was supposed to stay in Cambridge for three months. He ended up staying there for three years. In 1934 he returned to Italy but found a political situation that was not very congenial to him. Three years later he was offered the opportunity to move to the newly founded University of São Paulo, in Basile. When the Second World War broke out, Brazil declared war on the Axis powers and Occhialini became an “enemy alien” (a situation similar to that of Enrico Fermi in the USA) and took refuge in the mountains.

Occhialini loved adventure and not only science: he was a great lover of mountaineering and speleology, taking part in various explorations, including the tragic exploration of the Gouffre de la Pierre Saint-Martin, in the Pyrenees mountains, when during a vertical drop of more than 300 meters the French speleologist Marcel Loubens lost his life in a terrible accident. In Brazil he lived as a guide. Even today there is a peak, difficult to climb, which pays homage to the Italian physicist: the “Pico Occhialini”.

At the end of the war, Occhialini returned to England to work at the Wills Laboratory in Bristol, beginning a collaboration with Cecil Powell. Between 1945 and 1948 he began a series of experiments on cosmic rays, making an important modification to the photographic plates used to detect particles: Occhialini suggested increasing the content of silver bromide inside the plates and exposing them to the Pic du Midi (in France). The results were exceptional. Beppo and Powell discovered the Pi meson (Pione), the famous particle theorized by Yukawa in 1935, mediator of the strong interaction that keeps protons and neutrons together in nuclei.

In 1950 Powell won the Nobel prize for physics “for his development of the photographic method of studying nuclear processes and his discoveries concerning mesons made with this method”. Once again Occhialini’s work was not taken into consideration, being excluded for the second time.

The question of the missed Nobels, even though many were the honors for Occhialini, is well summarized by a toast made by Bruno Pontecorvo (also one of the great excluded) during a dinner:

“I toast not to Beppo, but to all of us: may we have the chance to collaborate with him. It is a sure way to win a Nobel Prize!”.

Despite the two exclusions, he was awarded the Wolf Prize for Physics in 1979. The SAX satellite, Italy’s first satellite for the study of gamma rays, was renamed Beppo-SAX in his honor.