Aage Bohr

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Aage Niels Bohr
Aage Bohr.jpg
Bohr in 1955
Born(1922-06-19)19 June 1922
Died8 September 2009(2009-09-08) (aged 87)
Copenhagen, Denmark
NationalityDanish
Alma mater University of Copenhagen
Known forGeometry of atomic nuclei
Awards
Scientific career
Fields Nuclear physics
Institutions
Thesis Rotational States of Atomic Nuclei (1954)

Aage Niels Bohr (Danish:  [ˈɔːwə ˌnels ˈboɐ̯ˀ] ( Loudspeaker.svg listen ); 19 June 1922 – 8 September 2009) was a Danish nuclear physicist who shared the Nobel Prize in Physics in 1975 with Ben Mottelson and James Rainwater "for the discovery of the connection between collective motion and particle motion in atomic nuclei and the development of the theory of the structure of the atomic nucleus based on this connection". [1] Starting from Rainwater's concept of an irregular-shaped liquid drop model of the nucleus, Bohr and Mottelson developed a detailed theory that was in close agreement with experiments. Since his father, Niels Bohr, had won the prize in 1922, he and his father were one of the six pairs of fathers and sons who have both won the Nobel Prize and one of the four pairs who have both won the Nobel Prize in Physics. [2]

Nuclear physics field of physics that deals with the structure and behavior of atomic nuclei

Nuclear physics is the field of physics that studies atomic nuclei and their constituents and interactions. Other forms of nuclear matter are also studied. Nuclear physics should not be confused with atomic physics, which studies the atom as a whole, including its electrons.

Nobel Prize in Physics One of the five Nobel Prizes established in 1895 by Alfred Nobel

The Nobel Prize in Physics is a yearly award given by the Royal Swedish Academy of Sciences for those who have made the most outstanding contributions for humankind in the field of physics. It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895 and awarded since 1901; the others being the Nobel Prize in Chemistry, Nobel Prize in Literature, Nobel Peace Prize, and Nobel Prize in Physiology or Medicine.

James Rainwater American physicist

Leo James Rainwater was an American physicist who shared the Nobel Prize in Physics in 1975 for his part in determining the asymmetrical shapes of certain atomic nuclei.

Contents

Early life

Aage Niels Bohr was born in Copenhagen on 19 June 1922, the fourth of six sons of the physicist Niels Bohr and his wife Margrethe Bohr (née Nørlund). [3] His oldest brother, Christian, died in a boating accident in 1934, [4] and his youngest, Harald, from childhood meningitis. [5] Of the others, Hans became a physician; Erik, a chemical engineer; and Ernest, a lawyer and an Olympic athlete who played field hockey for Denmark at the 1948 Summer Olympics in London. [6] [7] The family lived at the Institute of Theoretical Physics at the University of Copenhagen, now known as the Niels Bohr Institute, where he grew up surrounded by physicists who were working with his father, such as Hans Kramers, Oskar Klein, Yoshio Nishina, Wolfgang Pauli and Werner Heisenberg. [3] In 1932, the family moved to the Carlsberg Æresbolig, a mansion donated by Carl Jacobsen, the heir to Carlsberg breweries, to be used as an honorary residence by the Dane who had made the most prominent contribution to science, literature or the arts. [8]

Copenhagen Capital of Denmark

Copenhagen is the capital and most populous city of Denmark. As of July 2018, the city has a population of 777,218. It forms the core of the wider urban area of Copenhagen and the Copenhagen metropolitan area. Copenhagen is situated on the eastern coast of the island of Zealand; another small portion of the city is located on Amager, and is separated from Malmö, Sweden, by the strait of Øresund. The Øresund Bridge connects the two cities by rail and road.

Physicist scientist who does research in physics

A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate causes of phenomena, and usually frame their understanding in mathematical terms. Physicists work across a wide range of research fields, spanning all length scales: from sub-atomic and particle physics, through biological physics, to cosmological length scales encompassing the universe as a whole. The field generally includes two types of physicists: experimental physicists who specialize in the observation of physical phenomena and the analysis of experiments, and theoretical physicists who specialize in mathematical modeling of physical systems to rationalize, explain and predict natural phenomena. Physicists can apply their knowledge towards solving practical problems or to developing new technologies.

Niels Bohr Danish physicist

Niels Henrik David Bohr was a Danish physicist who made foundational contributions to understanding atomic structure and quantum theory, for which he received the Nobel Prize in Physics in 1922. Bohr was also a philosopher and a promoter of scientific research.

Bohr went to high school at Sortedam Gymnasium  [ da ] in Copenhagen. In 1940, shortly after the German occupation of Denmark in April, he entered the University of Copenhagen, where he studied physics. He assisted his father, helping draft correspondence and articles related to epistemology and physics. [3] In September 1943, word reached his family that the Nazis considered them to be Jewish, because Aage's grandmother, Ellen Adler Bohr, had been Jewish, and that they therefore were in danger of being arrested. The Danish resistance helped the family escape by sea to Sweden. [9] Bohr arrived there in October 1943, and then flew to Britain on a de Havilland Mosquito operated by British Overseas Airways Corporation. The Mosquitoes were unarmed high-speed bomber aircraft that had been converted to carry small, valuable cargoes or important passengers. By flying at high speed and high altitude, they could cross German-occupied Norway, and yet avoid German fighters. Bohr, equipped with parachute, flying suit and oxygen mask, spent the three-hour flight lying on a mattress in the aircraft's bomb bay. [10]

Epistemology A branch of philosophy concerned with the nature and scope of knowledge

Epistemology is the branch of philosophy concerned with the theory of knowledge.

Rescue of the Danish Jews

The rescue of the Danish Jews occurred during Nazi Germany's occupation of Denmark during World War II. On October 1, 1943, Nazi leader Adolf Hitler ordered Danish Jews to be arrested and deported. Despite great personal risk, the Danish resistance movement, with the assistance of many Danish citizens, managed to evacuate 7,220 of Denmark's 7,800 Jews, plus 686 non-Jewish spouses, by sea to nearby neutral Sweden.

de Havilland Mosquito Multi-role combat aircraft

The de Havilland DH.98 Mosquito is a British twin-engine shoulder-winged multi-role combat aircraft, introduced during the Second World War, unusual in that its frame is constructed mostly of wood. It was nicknamed The Wooden Wonder, or "Mossie". Lord Beaverbrook, Minister of Aircraft Production, nicknamed it "Freeman's Folly", alluding to Air Chief Marshal Sir Wilfred Freeman, who defended Geoffrey de Havilland and his design concept against orders to scrap the project. In 1941 it was one of the fastest operational aircraft in the world.

On arrival in London, Bohr rejoined his father, who had flown to Britain the week before. [10] He officially became a junior researcher at the Department of Scientific and Industrial Research, but actually served as personal assistant and secretary to his father. The two worked on Tube Alloys, the British atomic bomb project. On 30 December 1943, they made the first of a number of visits to the United States, where his father was a consultant to the Manhattan Project. [11] Due to his father's fame, they were given false names; Bohr became James Baker, and his father, Nicholas Baker. [12] In 1945, the director of the Los Alamos Laboratory, Robert Oppenheimer, asked them to review the design of the modulated neutron initiator. They reported that it would work. That they had reached this conclusion put Enrico Fermi's concerns about the viability of the design to rest. [12] The initiators performed flawlessly in the bombs used in the atomic bombings of Hiroshima and Nagasaki in August 1945. [13]

The Department of Scientific and Industrial Research was a department of the British Government responsible for the organisation, development and encouragement of scientific and industrial research. At the outbreak of World War I, "Britain found ... it was dangerously dependent on enemy industries". At the request of the Board of Trade, the Board of Education prepared a White Paper under the chairmanship of Sir William McCormick. The DSIR was set up to fill the roles that the White Paper specified: "to finance worthy research proposals, to award research fellowships and studentships [in universities], and to encourage the development of research associations in private industry and research facilities in university science departments. [It] rapidly assumed a key role in coordinating government aid to university research. It maintained these roles until 1965. The annual budget during its first year, 1915, was £1,000,000.

Tube Alloys Military R&D program codename

Tube Alloys was the code name of the research and development programme authorised by the United Kingdom, with participation from Canada, to develop nuclear weapons during the Second World War. Starting before the Manhattan Project in the United States, the British efforts were kept classified, and as such had to be referred to by code even within the highest circles of government.

Manhattan Project research and development project that produced the first atomic bombs

The Manhattan Project was a research and development undertaking during World War II that produced the first nuclear weapons. It was led by the United States with the support of the United Kingdom and Canada. From 1942 to 1946, the project was under the direction of Major General Leslie Groves of the U.S. Army Corps of Engineers. Nuclear physicist Robert Oppenheimer was the director of the Los Alamos Laboratory that designed the actual bombs. The Army component of the project was designated the Manhattan District; Manhattan gradually superseded the official codename, Development of Substitute Materials, for the entire project. Along the way, the project absorbed its earlier British counterpart, Tube Alloys. The Manhattan Project began modestly in 1939, but grew to employ more than 130,000 people and cost nearly US$2 billion. Over 90% of the cost was for building factories and to produce fissile material, with less than 10% for development and production of the weapons. Research and production took place at more than 30 sites across the United States, the United Kingdom, and Canada.

Career

In August 1945, with the war ended, Bohr returned to Denmark, where he resumed his university education, graduating with a master's degree in 1946, with a thesis concerned with some aspects of atomic stopping power problems. [3] In early 1948, Bohr became a member of the Institute for Advanced Study in Princeton, New Jersey. [14] While paying a visit to Columbia University, he met Isidor Isaac Rabi, who sparked in him an interest in recent discoveries related to the hyperfine structure of deuterium. This led to Bohr becoming a visiting fellow at Columbia from January 1949 to August 1950. [3] [15] While in the United States, Bohr married Marietta Soffer on 11 March 1950. They had three children: Vilhelm, Tomas and Margrethe. [15] [16]

Stopping power (particle radiation) retarding force acting on charged particles, typically alpha and beta particles, due to interaction with matter, resulting in loss of particle energy

Stopping power in nuclear and materials physics is defined as the retarding force acting on charged particles, typically alpha and beta particles, due to interaction with matter, resulting in loss of particle energy. Its application is important in areas such as radiation protection, ion implantation and nuclear medicine.

Institute for Advanced Study postgraduate center in Princeton, New Jersey

The Institute for Advanced Study (IAS) located 1 Einstein Drive, Princeton, New Jersey, in the United States, is an independent, postdoctoral research center for theoretical research and intellectual inquiry founded in 1930 by American educator Abraham Flexner, together with philanthropists Louis Bamberger and Caroline Bamberger Fuld.

Princeton, New Jersey Borough in New Jersey, United States

Princeton is a municipality with a borough form of government in Mercer County, New Jersey, United States, that was established in its current form on January 1, 2013, through the consolidation of the Borough of Princeton and Princeton Township. As of the 2010 United States Census, the municipality's population was 28,572, reflecting the former township's population of 16,265, along with the 12,307 in the former borough.

By the late 1940s it was known that the properties of atomic nuclei could not be explained by then-current models such as the liquid drop model developed by Niels Bohr amongst others. The shell model, developed in 1949 by Maria Goeppert-Mayer and others, allowed some additional features to be explained, in particular the so-called magic numbers. However, there were also properties that could not be explained, including the non-spherical distribution of charge in certain nuclei. [17] In a 1950 paper, James Rainwater of Columbia University suggested a variant of the drop model of the nucleus that could explain a non-spherical charge distribution. [18] Rainwater's model postulated a nucleus like a balloon with balls inside that distort the surface as they move about. He discussed the idea with Bohr, who was visiting Columbia at the time, and had independently conceived the same idea, and had, about a month after Rainwater's submission, submitted for publication a paper that discussed the same problem, but along more general lines. Bohr imagined a rotating, irregular-shaped nucleus with a form of surface tension. [19] Bohr developed the idea further, in 1951 publishing a paper that comprehensively treated the relationship between oscillations of the surface of the nucleus and the movement of the individual nucleons. [20]

Nuclear shell model model of the atomic nucleus

In nuclear physics and nuclear chemistry, the nuclear shell model is a model of the atomic nucleus which uses the Pauli exclusion principle to describe the structure of the nucleus in terms of energy levels. The first shell model was proposed by Dmitry Ivanenko in 1932. The model was developed in 1949 following independent work by several physicists, most notably Eugene Paul Wigner, Maria Goeppert Mayer and J. Hans D. Jensen, who shared the 1963 Nobel Prize in Physics for their contributions.

Magic number (physics) number of protons or neutrons that make a nucleus particularly stable

In nuclear physics, a magic number is a number of nucleons such that they are arranged into complete shells within the atomic nucleus. The seven most widely recognized magic numbers as of 2007 are 2, 8, 20, 28, 50, 82, and 126. For protons, this corresponds to the elements helium, oxygen, calcium, nickel, tin, lead and the hypothetical unbihexium, although 126 is so far only known to be a magic number for neutrons. Atomic nuclei consisting of such a magic number of nucleons have a higher average binding energy per nucleon than one would expect based upon predictions such as the semi-empirical mass formula and are hence more stable against nuclear decay.

Nucleon particle that makes up the atomic nucleus (proton or neutron)

In chemistry and physics, a nucleon is either a proton or a neutron, considered in its role as a component of an atomic nucleus. The number of nucleons in a nucleus defines an isotope's mass number.

Upon his return to Copenhagen in 1950, Bohr began working with Ben Mottelson to compare the theoretical work with experimental data. In three papers, that were published in 1952 and 1953, Bohr and Mottelson demonstrated close agreement between theory and experiment; for example, showing that the energy levels of certain nuclei could be described by a rotation spectrum. [21] [22] [23] They were thereby able to reconcile the shell model with Rainwater's concept. [19] This work stimulated many new theoretical and experimental studies. [17] Bohr, Mottelson and Rainwater were jointly awarded the 1975 Nobel Prize in Physics "for the discovery of the connection between collective motion and particle motion in atomic nuclei and the development of the theory of the structure of the atomic nucleus based on this connection". [1] Because his father had been awarded the prize in 1922, Bohr became one of only four pairs of fathers and sons to win the Nobel Prize in Physics. [24]

Only after doing his Nobel Prize-winning research did Bohr receive his doctorate from the University of Copenhagen, in 1954, writing his thesis on "Rotational States of Atomic Nuclei". [25] Bohr became a professor at the University of Copenhagen in 1956, and, following his father's death in 1962, succeeded him as director of the Niels Bohr Institute, a position he held until 1970. He remained active there until he retired in 1992. [26] He was also a member of the board of the Nordic Institute for Theoretical Physics (Nordita) from its inception in 1957, and was its director from 1975 to 1981. [27] In addition to the Nobel Prize, he won the Dannie Heineman Prize for Mathematical Physics in 1960, the Atoms for Peace Award in 1969, H.C. Ørsted Medal in 1970, Rutherford Medal and Prize in 1972, John Price Wetherill Medal in 1974, and the Ole Rømer medal in 1976. [14] [28] [29] Bohr and Mottelson continued to work together, publishing a two-volume monograph, Nuclear Structure. The first volume, Single-Particle Motion, appeared in 1969; the second, Nuclear Deformations, in 1975. [3]

In 1972 he was awarded an honorary degree, doctor philos. honoris causa, at the Norwegian Institute of Technology, later part of Norwegian University of Science and Technology. [30]

In 1981, Bohr became a founding member of the World Cultural Council. [31]

His wife Marietta died on 2 October 1978. [16] In 1981, he married Bente Scharff Meyer. [32] His son, Tomas Bohr, is a Professor of Physics at the Technical University of Denmark, working in the area of fluid dynamics. [33] Aage Bohr died in Copenhagen on 9 September 2009. [26] He was survived by his second wife and children. [32]

Notes

  1. 1 2 "The Nobel Prize in Physics 1975". The Nobel Foundation. Retrieved 12 May 2015.
  2. "Nobel Prize FAQ". The Nobel Foundation. Retrieved 16 December 2015.
  3. 1 2 3 4 5 6 "Aage N. Bohr – Biographical". The Nobel Foundation. Retrieved 12 May 2015.
  4. Stuewer 1985, p. 204.
  5. Pais 1991, pp. 226, 249.
  6. "Niels Bohr – Biography". Nobelprize.org . Retrieved 10 November 2011.
  7. "Ernest Bohr Biography and Olympic Results – Olympics". Sports-Reference.com. Retrieved 12 February 2013.
  8. Pais 1991, pp. 322–333.
  9. Rhodes 1986, pp. 483–484.
  10. 1 2 Jones 1985, p. 280.
  11. Gowing 1964, pp. 248–249.
  12. 1 2 Hoddeson et al. 1993, p. 95.
  13. Hoddeson et al. 1993, pp. 264–265, 308–309, 390–397.
  14. 1 2 "Bohr, Aage Niels". Institute for Advanced Study. Archived from the original on 7 January 2013. Retrieved 13 May 2015.
  15. 1 2 Chang, Kenneth (10 September 2009). "Aage Bohr, Physicist's Son Who Won Nobel, Dies at 87". The New York Times .
  16. 1 2 "Marietta Bohr (Soffer) (1922–1978)". Geni.com. Retrieved 14 May 2015.
  17. 1 2 Bohr, Aage (11 December 1975). "Rotational Motion in Nuclei Nobel Lecture," (PDF). Copenhagen: The Niels Bohr Institute and Nordita. Retrieved 14 May 2015.
  18. Rainwater, James (August 1950). "Nuclear Energy Level Argument for a Spheroidal Nuclear Model". Physical Review . American Physical Society. 79 (3): 432–434. Bibcode:1950PhRv...79..432R. doi:10.1103/PhysRev.79.432.
  19. 1 2 Lewin, Roger; Sherwood, Martin; Walgate, Robert (23 October 1975). "Nobel Prizes 1975: Medicine, Chemistry and Physics … and fifty years ago". New Scientist . 68 (972). ISSN   0262-4079.
  20. Bohr, Aage (January 1951). "On the Quantization of Angular Momenta in Heavy Nuclei". Physical Review . American Physical Society. 81 (1): 134–138. Bibcode:1951PhRv...81..134B. doi:10.1103/PhysRev.81.134.
  21. Bohr, Aage; Mottelson, Ben R. (1953). "Collective and Individual-Particle Aspects of Nuclear Structure" (PDF). Matematisk-fysiske Meddelelser, Det Kongelige Danske Videnskabernes Selskab . 27 (16). Retrieved 30 March 2018.
  22. Bohr, Aage; Mottelson, Ben R. (January 1953). "Interpretation of Isomeric Transitions of Electric Quadrupole Type". Physical Review . American Physical Society. 89 (1): 316–317. Bibcode:1953PhRv...89..316B. doi:10.1103/PhysRev.89.316.
  23. Bohr, Aage; Mottelson, Ben R. (May 1953). "Rotational States in Even-Even Nuclei". Physical Review . American Physical Society. 90 (4): 717–719. Bibcode:1953PhRv...90..717B. doi:10.1103/PhysRev.90.717.2.
  24. "Facts on the Nobel Prizes in Physics". The Nobel Foundation. Retrieved 12 May 2015. The others: William Henry Bragg (1915) and William Lawrence Bragg (1915); J. J. Thomson (1906) and George Paget Thomson (1937); and Manne Siegbahn (1924) and Kai M. Siegbahn (1981). Two pairs of fathers and sons have won Nobel Prizes in other fields: Hans von Euler-Chelpin (chemistry, 1929) and Ulf von Euler (medicine, 1970); and Arthur Kornberg (medicine, 1969) and Roger D. Kornberg (chemistry, 2006).
  25. "Rotational States of Atomic Nuclei". Columbia University. 1954. Retrieved 14 May 2015.
  26. 1 2 Anderson, Morten Garly (10 September 2009). "Nobelprisvinderen Aage Bohr er død ("Nobel Prize winner Aage Bohr has died")". Viden (in Danish). Archived from the original on 13 September 2009.
  27. "Nobel Laureate Aage Bohr has died". Niels Bohr Institute . Retrieved 14 May 2015.
  28. Zichichi, Antonino. "Aage Bohr". Pontifical Academy of Sciences . Retrieved 30 May 2012.
  29. "Rutherford medal recipients". Institute of Physics . Retrieved 14 May 2015.
  30. "Honorary doctors at NTNU". Norwegian University of Science and Technology.
  31. "About Us". World Cultural Council . Retrieved 8 November 2016.
  32. 1 2 Close, Frank (14 September 2009). "Aage Bohr". The Guardian . Retrieved 12 September 2015.
  33. "Tomas Bohr". Technical University of Denmark . Retrieved 14 May 2015.

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References