Amaldi, Edoardo

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AMALDI, EDOARDO

(b. Carpaneto Piacentino, Italy, 5 September 1908; d. Rome, Italy, 5 December 1989)

nuclear physics, cosmic ray physics, science policy, international collaboration, arms control.

One of the leading figures of twentieth-century Italian science in the field of fundamental experimental physics, Amaldi contributed to nuclear physics in the 1930s and 1940s and to cosmic ray and particle physics in the postwar years; he also became one of the pioneers in the experimental search for gravitational waves in the early 1970s. Far more important than his direct contributions to knowledge, however, was his role as a true statesman of science. It is largely thanks to his drive and initiative that Italian physics was able to emerge from the collapse following World War II; he was instrumental in finding adequate support and building solid institutions in the postwar years. He was also one of the main actors in the process that turned the dreams of large transnational scientific projects among European countries into realities, first and foremost the Conseil Européen pour la recherche nucléaire (CERN; European Organization for Nuclear Research).

In Rome with Fermi. As a boy, Amaldi lived in a scientific and academic environment. His parents were Laura Basini and Ugo Amaldi, the latter a distinguished mathematician and university professor. Ugo’s academic career led him from Modena to Padua, where young Edoardo went to secondary school, and finally, in 1924, to the University of Rome. There, Ugo became colleagues with some of the outstanding Italian mathematicians of the time, such as Vito Volterra, Tullio Levi-Civita, Guido Castelnuovo, and Federigo Enriques. Edoardo enrolled at the University of Rome in 1925 as a student of engineering. Two years later, however, he switched to physics, attracted—as were a few other brilliant students, such as Emilio Segrè and Ettore Majorana—by the presence of Enrico Fermi, who had just been called upon by the director of the Istituto fisico (Physics Institute), Orso Mario Corbino, to occupy the first chair of theoretical physics ever established in Italy. Amaldi took his degree in physics in July 1929 with a dissertation on the Raman spectrum of the molecule of benzene; his thesis advisor was Franco Rasetti, who had joined Fermi in moving from Florence to Rome, first as Corbino’s assistant and, beginning in 1930, as professor of spectroscopy.

By the end of the 1920s, a strong group of young physicists was established at the Physics Institute on Rome’s via Panisperna (Panisperna Street), and research efforts were slowly but deliberately shifted from the original concern with spectroscopic problems to the new frontier of nuclear physics. Under Fermi’s leadership, it became common practice to send young people to leading research centers abroad for extended periods to improve their skills. In 1931 Amaldi spent ten months working in Leipzig, Germany, in Peter Debye’s laboratory, learning Xray diffraction techniques in liquids; he also spent time at the Cavendish Laboratory in Cambridge, England, during the summer of 1934 and at Columbia University in New York City and the Department of Terrestrial Magnetism of the Carnegie Institution in Washington, D.C., in the summer of 1936.

Following the discovery of artificially induced radioactivity in January 1934, Fermi, soon joined by the whole team, began a methodical search of the effects produced by neutron bombardment on every element known. Rather than use positively charged alpha particles as projectiles—as had been done in the previous experiments by Frédéric Joliot and Iréne Curie—Fermi chose to utilize neutrons emitted by a radon-berillium source, reasoning that the uncharged particles would have greater ability to penetrate the atomic nucleus. The very expensive radon needed to build this source was available to him through the generosity of Corbino’s former assistant, Giulio Cesare Trabacchi, then director of the Public Health Institute’s Physics Laboratory.

The long series of experiments were of paramount importance for the understanding of nuclear properties, and they culminated in October 1934 with the discovery of the greater efficiency of slowed-down neutrons in activating nuclear transformations. It was a truly new way of doing group work in experimental physics; the published papers carried the signature of all team members (Fermi, Rasetti, Amaldi, Segrè, the chemist Oscar D’Agostino, and later on the younger Bruno Pontecorvo). Clearly, Fermi was the intellectual leader and the driving force, and for the results of these experiements he would receive in 1938 the Nobel Prize in Physics.

Most of the work in the following couple of years was done by Fermi and Amaldi. (Rasetti and Pontecorvo were mostly absent from Rome, and Segrè had moved to a professorship in Palermo.) During this period Amaldi acquired a competence in nuclear physics, particularly on the subject of neutron properties, that turned him into one of the leading authorities in the field. In 1937 he won a professorship at the University of Cagliari in Sardinia, but was instead immediately called on to occupy the chair of experimental physics in Rome left vacant by the sudden death of Corbino, a position that Amaldi kept until retirement. Amaldi kept working on nuclear physics with Fermi and Rasetti; together they designed and began to build a Cockroft-Walton accelerator, which was completed in 1939 and installed in the building of the Istituto di sanità pubblica (Public Health Institute).

By the late 1930s, however, the general situation in Italy was rapidly deteriorating; lack of funds and support to keep research competitive, the emergence of a clear alignment of Italian fascism with Hitler’s Germany, and the racial laws promulgated in 1938 led to the forced or voluntary emigration of a great number of Italian physicists. This included Fermi, who left for the United States at the end of 1938. When the war began, Amaldi was the only member of the original via Panisperna group remaining in the country.

The War Years. Left alone in Rome with a small group of younger people, Amaldi for a while concentrated his research efforts on nuclear fission, working with a mixed group of physicists from the Physics Institute and the Public Health Institue, while the theoretical work was done in collaboration with Gian-Carlo Wick, who had

replaced Fermi. This activity was interrupted in 1940, when Amaldi was sent to the African front for a few months. Back in Rome, research on fission continued briefly, but by 1941 the suspicion had arisen that working on fission exposed the group to the danger of being recruited to do war-related research. It was thus decided to abandon research on fission and instead direct experimental work toward the problems of proton-neutron scattering, while some of the younger group members began promising research activity on cosmic rays. Though research conditions during the war were difficult, Rome was in a better situation than centers in the north, especially after liberation in June 1944. Most of what had been left of active research in Italy, both in terms of expertise and people, was concentrated in Rome at the end of the war. In collaboration with Wick and Gilberto Bernardini, who had grown in the research tradigion inaugerated in Florence by Bruno Rossi, Amaldi deliberately took upon himself the task of the reconstructing physics in his country, starting from the vantage point offered by his location in the capital. The first move, successfully completed in October 1945, was to secure the establishment of a research center for nuclear and elementary particle physics from the reconstituted Consiglio nazionale delle ricerche (National Research Council, CNR) at the Physics Institute in Rome.

The Years of Reconstruction. During a trip by Amaldi to the United States in 1946, Fermi offered him a chair at the University of Chicago. Amaldi declined, having by now resolved that his duty was to take care of scientific development in his homeland. On the occasion of his trip, Amaldi was confronted with the sensitive character that his research interests had acquired during the war. For example, restrictions were imposed for security reasons on discussion of some matters of real or supposed military interest; thus, beyond a certain limit it was impossible for him to talk freely even with Fermi about nuclear problems. He found that disturbing on ethical grounds and harmful to scientific progress. That experience strenghtened in him the conviction, already matured during the war years, that any genuine scientific collaboration should be planned in total freedom from military control, a general policy that he strictly adhered to in the following years.

Direct contact with the new level of financial support given to nuclear and particle physics in the United States after the war convinced Amaldi that the best course of action for Italian physics would be to abandon ambitious programs in fields requiring expensive instrumentation, such as the postwar generation of particle accelerators, and to concentrate on those research sectors where good results could reasonably be obtained with the modest means at his country’s disposal. As a consequence, focus was placed on research in cosmic rays, a relatively inexpensive field where Italian physicists could rely on a solid tradition. A first significant step was the construction of a high-altitude laboratory in the Alps in 1947, while new research centers followed in the footsteps of the Rome center, namely, Padua in 1948, Turin in 1951, and Milan in 1952.

Meanwhile, Amaldi was also giving support to the first initiatives aimed at the development of applied nuclear research, training young engineers and physicists and finding support among politicians interested in the exploitation of nuclear energy for civilian purposes, a program that led a few years later to the construction of Italy’s first power reactors. Relying on the strength of this active network and on the support of CNR’s president Gustavo Colonnetti, Amaldi and Bernardini could then take a significant step in reshaping the institutional panorama of Italian physics with the establishment in 1951 of the Istituto nazionale di fisica nucleare (National Institute of Nuclear Physics, INFN), financed by CNR through the channel of the Comitato nazionale per le ricerche nucleari (National committee for nuclear research, CNRN), a body in charge of both fundamental and applied nuclear research. Bernardini was the first president of INFN. Amaldi followed him, serving from March 1960 to January 1966.

The INFN physicists’ first important set of activities was their participation in three different international collaborations between 1952 and 1954 that launched high-altitude ballons carrying photographic emulsions for the study of cosmic rays. The Rome group led by Amaldi was actively present in the first and second collaborations. Soon after, a more ambitious program was initiated for the creation of a national laboratory for high-energy physics, equipped with a competitive accelerator. Formulated in 1954, the project became reality in less than five years. The electrosynchrotron of the Laboratori nazionali in Frascati, near Rome, started operating in February 1959. Amaldi’s extremely active role, both in the physics community and with politicians and administrators in Rome, was in the end decisive in winning a site close to Rome as the location for the new laboratory. This was in accordance with a general design that left the development of nuclear facilities for civilian purposes to the northern areas of the country and concentrated fundamental research near the capital.

Building European Science. Soon after the end of the war, physicists throughout Europe came to realize that only a collaborative effort between several countries could keep Europe competitive under the new conditions of the postwar years. Plans for a great European laboratory for fundamental physics were first explicitly advanced around 1950 on several occasions. Amaldi was one of the strongest

advocates of the idea from the very beginning, an idea he could effectively push in his capacity as vice president (from 1948 to 1954) of the International Union of Pure and Applied Physics (IUPAP). The ambitious plan quickly took form with the institutional support offered by the United Nations Economic, Social, and Cultural Organization (UNESCO). Amaldi and the French physicist Pierre Auger, director of the scientific section of UNESCO, were the driving force for a project that had a great power of attraction for the younger generations of European physicists but that also had to face difficulties and opposition, on both the scientific and governmental levels.

By May 1951, however, a detailed plan was approved by a selected team of experts from eight countries, and early in 1952 an intergovernmental conference established a provisional organization, which took the name of Conseil Européen pour la recherche nucléaire. Amaldi was elected general secretary of the provisional CERN; in that temporary post he supervised all the crucial phases of the new institution’s infancy, including the early stage of the work on the site of the laboratory, which was finally built on grounds allocated by the city of Geneva in Switzerland. He left his position when CERN entered into official existence in September 1954, refusing the offer to become the first general director, inspired among other considerations by his desire to return to more active research in physics. Paralleling the development of the laboratory in Frascati, CERN’s large proton synchrotron was successfully completed in 1959, reaching a record-setting energy of 28 GeV. Amaldi kept strong ties with CERN, maintaining a position on the scientific bodies shaping its policy.

In 1963 Amaldi created the European Committee for Future Accelerators (ECFA), an independent body charged with the design of the new machines to be built in Europe at CERN and beyond; he was its president until 1969. In the late 1960s he was president of the group that planned the new 300 GeV proton synchrotron for CERN, a project that was finally approved by the CERN member states in 1971, when Amaldi was in charge as president of the CERN council. Occupying important positions both at INFN and at CERN simultaneously often put Amaldi in the delicate position of balancing resources between domestic developments and international cooperation, as when a choice had to be made between giving Italy’s support to the 300 GeV machine project in Geneva or launching a great effort towards a new Italian proton synchrotron. On that occasion he was strongly in favor of keeping the CERN project alive, even if that meant giving up an interesting program at home. He was convinced that priority had to be granted to Europe, both because Europe would ultimately always have access to much larger resources and because of his strong conviction concerning the importance of transnational cultural and scientific collaboration.

A network of scientists and politicians similar to the one that had contributed to the success of CERN arose in the early 1960s, when a joint European effort in space science was discussed. Again, Amaldi took a leading role in launching the idea and pushing it through scientific and political circles. As a result, in 1964 the European Space Research Organization was established; ten years later it gave birth to the European Space Agency. One distinctive feature of the new institution, on which Amaldi insisted repeatedly, was its lack of any connection with military interests; in his view, such projects had to blend a genuine international character with a total independence from any military-oriented goals, which, he believed, would endanger freedom of research by imposing secrecy and preventing a genuine transnational collaboration.

Cosmic Rays and Particle Physics. In the time left over from academic and administrative duties and frantic activity as an organizer and planner of science, Amaldi continued to do active research and lead groups of younger collaborators, moving his interest toward the field of cosmic ray physics. An exciting discovery came during the collaborative high-altitude balloon flights in 1953: A track was found in one of the emulsions exposed to cosmic radiation that could be interpreted as evidence of the annihilation process of an antiproton, a particle whose existence was taken for granted on a theoretical basis but that had never been observed. To gain better support for the scant evidence offered by that single track, Amaldi turned to his former friend Emilio Segrè, now at the University of California at Berkeley, proposing a joint research program aimed at the detection of similar events in emulsions exposed to the beam of protons produced by Berkeley’s Bevatron, at the time the most powerful accelerator in the world and the only one reaching an energy high enough to produce proton-antiproton pairs. The Rome-Berkeley collaboration lasted for a couple of years, giving a number of important results on antiprotons and their annihilation properties. The first confirmation of such a process clearly visible in emulsion tracks, however, did not come until a few weeks after Segrè and his group had independently detected the antiproton by a different experiment that relied on counters instead of emulsions. For this discovery, Segrè and Owen Chamberlain were awarded the Nobel Prize in Physics in 1959. The Rome group just missed receiving that recognition. It was further confirmation for Amaldi of the absolute need for European physicists to push hard on the CERN program and to invest in large-scale, competitive experimental facilities.

The Late Years. A completely new research field was opened to Italian physicists by Amaldi in the 1970s. His interest in the problem of the experimental detection of gravitational waves went back to a course on that subject

given by Joseph Weber, the pioneer of that kind of instrumentation, at a summer school in Varenna in 1962. In 1970 a group under Amaldi’s leadership was formed in Rome with the aim of designing and building cryogenic detectors for gravitational waves. In the beginning, small-scale antennae were planned and put into operation. A number of constructive problems connected with the design and proper working of these instruments were tackled and solved in the course of years, which resulted in a better understanding of the underlying physics. Larger detectors were built in succession, in Rome and Frascati and then at CERN: There the cryogenic antenna Explorer was installed in the 1980s, which in 1989 attained the highest sensitivity ever reached.Throughout this period Amaldi, while leaving to others the responsibilty for the actual direction of research, played an active role both in the planning and execution of experiments and in recruiting young students to the field. The detection of gravitational waves remained an open problem at the beginning of the twenty-first century; huge facilities have been built for the purpose in large international collaborations with an important presence of active Italian physicists, a legacy of a tradition that goes back to Amaldi’s initial foresight.

Along with active scientific research, in his mature years Amaldi increasingly devoted time to collecting his memories and putting on paper those moments in the history of physics to which he had been a personal witness. Starting with commemorations of friends and colleagues and recollections of relevant events, this reconstruction of a personal and collective memory slowly evolved into the production of more profound writings, characterized by growing insight into the more general historical context and a care for sources and documentation not usually found in similar works by scientists. In his writing he was helped by a habit, developed during his early days as leader of the Italian physics community, of keeping every relevant document related to his work and to the institutions with which he was involved. His personal archive helped him to produce works halfway between the traditional scientist’s recollection and the scholarly research of the independent historian, which will be an invaluable source for further studies in the history of twentieth-century science for some time to come.

Peace and Arms Control. A concern for peace and a strong feeling of the responsible role the scientific community should play in achieving it had always been a natural complement to Amaldi’s unshakable belief in the open character of science and the need for international cooperation. Together with his colleagues who, like him, stayed in Italy during the war, he was spared the difficult decision of whether to take part in projects related to the possible military use of nuclear physics—although he honestly admitted later that, had this not been the case, he would in the end have put his competence in the service of the Allies, who looked to him, beyond any doubt, the right side on which to fight. After the war he followed with interest the first attempts of American physicists to establish some sort of organization aimed at the control of the arms race. When the Pugwash movement for the control of nuclear weapons was created in 1957, following a 1955 appeal by Bertrand Russell and Albert Einstein, he was asked at the beginning to participate. He attended the second Pugwash meeting in 1958 and was a member of the Continuing Committee, the governing body of the movement, from 1962 to 1972.

Together with his physicist colleague Carlo Schaerf, Amaldi was the founder of the International School on Disarmament and Research on Conflicts (ISODARCO) and acted as its president from its inception in 1966 to his death. In 1982 he led a delegation of Italian physicists to the president of Italy to present a resolution of concern with the ongoing arms race and the danger to Europe created by the installation in Europe and Italy of Cruise missiles. As a follow-on to this document, the Unione scienziati per il disarmo (Italian Union of Scientists for Disarmament, USPID) was founded. This organization has kept the discussion of disarmament issues alive in Italy by organizing international meetings and spreading documented scientific information on these issues. One of Amaldi’s last official public speeches was in 1987, when he led a delegation of Italian scientists to the International Forum organized in Moscow by Soviet general secretary Mikhail Gorbachev, in the new distension scenario that was opening at the time.

Amaldi was married to Ginestra Giovene, one of the very few women among the physics students in Rome during the 1930s. They had three children: Ugo, Francesco, and Daniela. Ugo followed in his father’s footsteps and became a high-energy physicist.

Amaldi was a member of a number of academies and learned societies. In 1988 and 1989 he was the president of the Accademia dei Lincei, Italy’s national academy. Amaldi retained his full capacities until dying suddenly of a stroke at age eighty-one.

BIBLIOGRAPHY

Amaldi’s papers are deposited in the library of the Physics Department at the University La Sapienza in Rome. They consist of a large collection (more than 650 boxes) of correspondence, notebooks, documents, drawings, and photos. A full list of Amaldi’s approximately two hundred scientific publications can be found in Carlo Rubbia Piero Angela, Edoardo Amaldi scienziato e cittadino d’Europa (Milan, Italy: Leonardo Periodici, 1992).

WORKS BY AMALDI

The Production and Slowing Down of Neutrons. Handbuch der Physik series, 38. Berlin: Springer-Verlag, 1959. A fundamental review of neutron physics.

“From the Discovery of the Neutron to the Discovery of Nuclear Fission.” Physics Report 111, nos. 1–4 (1984): 1–331. An excellent blend of technical competence and historical accuracy.

Da via Panisperna all’America: I fisici italiani nella seconda guerra mondiale. Edited by Giovanni Battimelli and Michelangelo De Maria. Rome, Italy: Editori Riuniti, 1997. Includes an unpublished manuscript by Amaldi and a selection of correspondence covering the years 1938–1946.

20th Century Physics: Essays and Recollections, a Selection of Historical Writings. Edited by Giovanni Battimelli and Giovanni Paoloni. Singapore; River Edge, NJ: World Scientific, 1998. A large selection of historical writings by Amaldi, with English translation of those originally published in Italian.

OTHER SOURCES

Battimelli, Giovanni, Michelangelo De Maria, and Giovanni Paoloni. L’istituto nazionale di fisica nucleare: Storia di una comunità di ricerca. Rome: Laterza, 2002. Amaldi is the key figure throughout the volume.

Hermann, Armin, John Krige, Dominique Pestre, et al. History of CERN. 3 vols. Amsterdam, New York: North-Holland Physics Publications, 1987–1996. Of particular interest is the discussion in the first volume of Amaldi’s role in the early stages of CERN.

Rubbia, Carlo, and Piero Angela. Edoardo Amaldi scienziato e cittadino d’Europa. Milan: Leonardo Periodici, 1992. Includes a biography by Rubbia and a long interview conducted by Angela in 1980.

University of Roma la Sapienzem Department of Physics.Proceedings of the Conference “Edoardo Amaldi. Physics, Politics of Research and Civil Commitment,” Rome, 20–21 December 1999. Giornale di Fisica, Quaderni di Storia della Fisica N. 7, 2000.

Giovanni Battimelli