Otto Robert Frisch

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Otto Robert Frisch
Otto Frisch ID badge.png
Otto Robert Frisch's wartime Los Alamos ID badge photo.
Born(1904-10-01)1 October 1904
Died22 September 1979(1979-09-22) (aged 74)
Cambridge, United Kingdom
Nationality Austrian
CitizenshipAustria
United Kingdom
Known for Atomic bomb
Awards Fellow of the Royal Society [1]
Scientific career
Fields Physics
Influences Rudolf Peierls
Signature
Otto Robert Frisch signature.svg

Otto Robert Frisch FRS [1] (1 October 1904 – 22 September 1979) was an Austrian physicist who worked on nuclear physics. With Lise Meitner he advanced the first theoretical explanation of nuclear fission (coining the term) and first experimentally detected the fission by-products. Later, with his collaborator Rudolf Peierls [1] he designed the first theoretical mechanism for the detonation of an atomic bomb in 1940. [2]

Fellow of the Royal Society Elected Fellow of the Royal Society, including Honorary, Foreign and Royal Fellows

Fellowship of the Royal Society is an award granted to individuals that the Royal Society of London judges to have made a 'substantial contribution to the improvement of natural knowledge, including mathematics, engineering science and medical science'.

Austria Federal republic in Central Europe

Austria, officially the Republic of Austria, is a country in Central Europe comprising 9 federated states. Its capital, largest city and one of nine states is Vienna. Austria has an area of 83,879 km2 (32,386 sq mi), a population of nearly 9 million people and a nominal GDP of $477 billion. It is bordered by the Czech Republic and Germany to the north, Hungary and Slovakia to the east, Slovenia and Italy to the south, and Switzerland and Liechtenstein to the west. The terrain is highly mountainous, lying within the Alps; only 32% of the country is below 500 m (1,640 ft), and its highest point is 3,798 m (12,461 ft). The majority of the population speaks local Bavarian dialects as their native language, and German in its standard form is the country's official language. Other regional languages are Hungarian, Burgenland Croatian, and Slovene.

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.

Contents

Early life

Frisch was born in Vienna in 1904, the son of Justinian Frisch, a painter, and Auguste Meitner Frisch, a concert pianist. He himself was talented at both but also shared his aunt Lise Meitner's love of physics and commenced a period of study at the University of Vienna, graduating in 1926 with some work on the effect of the newly discovered electron on salts.

Vienna Capital city and state in Austria

Vienna is the federal capital and largest city of Austria, and one of the nine states of Austria. Vienna is Austria's primate city, with a population of about 1.9 million, and its cultural, economic, and political centre. It is the 7th-largest city by population within city limits in the European Union. Until the beginning of the 20th century, it was the largest German-speaking city in the world, and before the splitting of the Austro-Hungarian Empire in World War I, the city had 2 million inhabitants. Today, it has the second largest number of German speakers after Berlin. Vienna is host to many major international organizations, including the United Nations and OPEC. The city is located in the eastern part of Austria and is close to the borders of the Czech Republic, Slovakia, and Hungary. These regions work together in a European Centrope border region. Along with nearby Bratislava, Vienna forms a metropolitan region with 3 million inhabitants. In 2001, the city centre was designated a UNESCO World Heritage Site. In July 2017 it was moved to the list of World Heritage in Danger.

Lise Meitner Austrian-Swedish physicist

Lise Meitner was an Austrian-Swedish physicist who worked on radioactivity and nuclear physics. Meitner, Otto Hahn and Otto Robert Frisch led the small group of scientists who first discovered nuclear fission of uranium when it absorbed an extra neutron; the results were published in early 1939. Meitner, Hahn and Frisch understood that the fission process, which splits the atomic nucleus of uranium into two smaller nuclei, must be accompanied by an enormous release of energy. Nuclear fission is the process exploited by nuclear reactors to generate heat and, subsequently, electricity. This process is also one of the basics of nuclear weapons that were developed in the U.S. during World War II and used against Japan in 1945.

Electron subatomic particle with negative electric charge

The electron is a subatomic particle, symbol
e
or
β
, whose electric charge is negative one elementary charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have no known components or substructure. The electron has a mass that is approximately 1/1836 that of the proton. Quantum mechanical properties of the electron include an intrinsic angular momentum (spin) of a half-integer value, expressed in units of the reduced Planck constant, ħ. As it is a fermion, no two electrons can occupy the same quantum state, in accordance with the Pauli exclusion principle. Like all elementary particles, electrons exhibit properties of both particles and waves: they can collide with other particles and can be diffracted like light. The wave properties of electrons are easier to observe with experiments than those of other particles like neutrons and protons because electrons have a lower mass and hence a longer de Broglie wavelength for a given energy.

Nuclear physics

After some years working in relatively obscure laboratories in Germany, Frisch obtained a position in Hamburg under the Nobel Prize-winning scientist Otto Stern. Here he produced work on the diffraction of atoms (using crystal surfaces) and also proved that the magnetic moment of the proton was much larger than had been previously supposed. [3]

Hamburg City in Germany

Hamburg is the second-largest city in Germany with a population of over 1.8 million.

Nobel Prize set of annual international awards, primarily 5 established in 1895 by Alfred Nobel

The Nobel Prize is a set of annual international awards bestowed in several categories by Swedish and Norwegian institutions in recognition of academic, cultural, or scientific advances.

Otto Stern German physicist

Otto Stern was a German-American physicist and Nobel laureate in physics. He was the second most nominated person for a Nobel Prize with 82 nominations in the years 1925–1945, ultimately winning in 1943.

The accession of Adolf Hitler to the chancellorship of Germany in 1933 caused Otto Robert Frisch to make the decision to move to London, where he joined the staff at Birkbeck College and worked with the physicist Patrick Maynard Stuart Blackett on cloud chamber technology and artificial radioactivity. He followed this with a five-year stint in Copenhagen with Niels Bohr where he increasingly specialised in nuclear physics, particularly in neutron physics.

Adolf Hitler Leader of Germany from 1934 to 1945

Adolf Hitler was a German politician and leader of the Nazi Party. He rose to power as Chancellor of Germany in 1933 and later Führer in 1934. During his dictatorship from 1933 to 1945, he initiated World War II in Europe by invading Poland in September 1939. He was closely involved in military operations throughout the war and was central to the perpetration of the Holocaust.

Birkbeck, University of London public research university located in Bloomsbury, London, England

Birkbeck, University of London, is a public research university located in Bloomsbury London, England, and a constituent college of the federal University of London. Established in 1823 as the London Mechanics' Institute by its founder, Sir George Birkbeck, and its supporters, Jeremy Bentham, J. C. Hobhouse and Henry Brougham, Birkbeck has been one of the few institutions to specialise in evening higher education.

Cloud chamber

A cloud chamber, also known as a Wilson cloud chamber, is a particle detector used for visualizing the passage of ionizing radiation.

Nuclear fission

Otto Frisch, Lise Meitner, and Glenn Seaborg Lise Meitner.jpg
Otto Frisch, Lise Meitner, and Glenn Seaborg

During the Christmas holiday in 1938 he visited his aunt Lise Meitner in Kungälv. While there she received the news that Otto Hahn and Fritz Strassmann in Berlin had discovered that the collision of a neutron with a uranium nucleus produced the element barium as one of its byproducts. Hahn, in a letter to Meitner, called this new reaction a "bursting" of the uranium nucleus. Frisch and Meitner hypothesized that the uranium nucleus had split in two, explained the process, estimated the energy released, and Frisch coined the term fission to describe it.

Kungälv Place in Bohuslän, Sweden

Kungälv is a city and the seat of Kungälv Municipality in Västra Götaland County, Sweden. It had 22,768 inhabitants in 2010.

Otto Hahn German chemist

Otto Hahn was a German chemist and pioneer in the fields of radioactivity and radiochemistry. Otto Hahn discovered nuclear fission in 1938. He is referred to as the father of nuclear chemistry. He was awarded the Nobel Prize in Chemistry in 1944 for the discovery and the radiochemical proof of nuclear fission. This process is exploited by nuclear reactors and is one of the basics of nuclear weapons that were developed in the U.S. during World War II.

Friedrich Wilhelm "Fritz" Strassmann was a German chemist who, with Otto Hahn in early 1939, identified barium in the residue after bombarding uranium with neutrons, results which, when confirmed, demonstrated the previously unknown phenomenon of nuclear fission.

Political restraints of the Nazi era forced the team of Hahn and that of Frisch and Meitner (both of whom were Jewish) to publish separately. Hahn's paper described the experiment and the finding of the barium byproduct. [4] Meitner's and Frisch's paper explained the physics behind the phenomenon. [5]

Frisch went back to Copenhagen, where he was quickly able to isolate the pieces produced by fission reactions. [6] As Frisch himself later recalled, a fundamental idea of the direct experimental proof of the nuclear fission was suggested to him by George Placzek. [7] [8] Many feel that Meitner and Frisch deserved Nobel Prize recognition for their contributions to understanding fission. [9]

In mid-1939 Frisch left Denmark for what he anticipated would be a short trip to Birmingham, but the outbreak of World War II precluded his return. With war on his mind, he and the physicist Rudolf Peierls produced the Frisch–Peierls memorandum at the University of Birmingham, which was the first document to set out a process by which an atomic explosion could be generated. Their process would use separated uranium-235, which would require a fairly small critical mass and could be made to achieve criticality using conventional explosives to create an immensely powerful detonation. The memorandum went on to predict the effects of such an explosion—from the initial blast to the resulting fallout. This memorandum was the basis of British work on building an atomic device (the Tube Alloys project) and also that of the Manhattan Project on which Frisch worked as part of the British delegation. Frisch and Rudolf Peierls worked together in the Physics Department at the University of Birmingham 1939–40. [10] He went to America in 1943 having been hurriedly made a British citizen.

Manhattan Project

The Godiva device at Los Alamos Godiva-before-scrammed.jpg
The Godiva device at Los Alamos

In 1944 at Los Alamos, one of Frisch's tasks as the leader of the Critical Assemblies group was to accurately determine the exact amount of enriched uranium which would be required to create the critical mass, the mass of uranium which would sustain a nuclear chain reaction. [11] He did this by stacking several dozen 3 cm bars of enriched uranium hydride at a time and measuring rising neutron activity as the critical mass was approached. The hydrogen in the metal bars increased the time that the reaction required to accelerate. One day Frisch almost caused a runaway reaction by leaning over the stack, which he termed the "Lady Godiva assembly". [12] His body reflected neutrons back into the stack. Out of the corner of his eye he saw that the red lamps that flickered intermittently when neutrons were being emitted, were 'glowing continuously'. [12] Realizing what was happening, Frisch quickly scattered the bars with his hand. Later he calculated that the radiation dose was "quite harmless" but that if he "had hesitated for another two seconds before removing the material ... the dose would have been fatal". [12] "In two seconds he received, by the generous standards of the time, a full day's permissible dose of neutron radiation." [13] In this way his experiments determined the exact masses of uranium required to fire the Little Boy bomb over Hiroshima.

He also designed the "dragon's tail" or "guillotine" experiment in which a uranium slug was dropped through a hole in larger fixed mass of uranium, reaching just above critical mass (0.1%) for a fraction of a second. [14] At the meeting to approve the experiment, Richard Feynman, commenting on the transient danger involved, said it was "just like tickling the tail of a sleeping dragon." In the period of about 3 milliseconds, the temperature rose at a rate of 2000 °C per sec and over 1015 excess neutrons were emitted. [15]

Return to England

Left to right: William Penney, Otto Frisch, Rudolf Peierls and John Cockcroft in 1946 William Penney, Otto Frisch, Rudolf Peierls and John Cockroft.jpg
Left to right: William Penney, Otto Frisch, Rudolf Peierls and John Cockcroft in 1946

In 1946 he returned to England to take up the post of head of the nuclear physics division of the Atomic Energy Research Establishment at Harwell, though he also spent much of the next thirty years teaching at Cambridge where he was Jacksonian Professor of Natural Philosophy and a fellow of Trinity College.

Before he retired he designed [16] a device, SWEEPNIK, that used a laser and computer to measure tracks in bubble chambers. Seeing that this had wider applications, he helped found a company, Laser-Scan Limited, now known as 1Spatial, to exploit the idea.

Retirement

University of Birmingham - Poynting Physics Building - blue plaque University of Birmingham - Poynting Physics Building - blue plaques group - Frisch Peierls.jpg
University of Birmingham - Poynting Physics Building - blue plaque

He retired from the chair in 1972 as required by University regulations. [16] He died on 22 September 1979 and was cremated on 5 October at Cambridge City Crematorium. His son, Tony Frisch, is also a physicist.

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Nuclear fission nuclear reaction or a radioactive decay process in which the nucleus of an atom splits into smaller parts

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Werner Heisenberg German theoretical physicist

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The Frisch–Peierls memorandum was the first technical exposition of a practical nuclear weapon. It was written by expatriate German physicists Otto Frisch and Rudolf Peierls in March 1940 while they were both working for Mark Oliphant at the University of Birmingham in Britain during World War II.

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References

  1. 1 2 3 Peierls, R. (1981). "Otto Robert Frisch. 1 October 1904 – 22 September 1979". Biographical Memoirs of Fellows of the Royal Society . 27: 283–306. doi:10.1098/rsbm.1981.0012. JSTOR   769874.
  2. Bethe, H. A.; Winter, George (January 1980). "Obituary: Otto Robert Frisch". Physics Today. 33 (1): 99–100. Bibcode:1980PhT....33a..99B. doi:10.1063/1.2913924. Archived from the original on 2013-09-28.
  3. Frisch, Otto R.; Stern, Otto (1933). "Über die magnetische Ablenkung von Wasserstoffmolekülen und das magnetische Moment des Protons". Zeitschrift für Physik (in German). 85 (1–2): 4–16. Bibcode:1933ZPhy...85....4F. doi:10.1007/BF01330773.
  4. Hahn, O.; Strassmann, F. (1939). "Über den Nachweis und das Verhalten der bei der Bestrahlung des Urans mittels Neutronen entstehenden Erdalkalimetalle [On the detection and characteristics of the alkaline earth metals formed by irradiation of uranium without neutrons]". Naturwissenschaften (in German). 27 (1): 11–15. Bibcode:1939NW.....27...11H. doi:10.1007/BF01488241. The authors were identified as being at the Kaiser-Wilhelm-Institut für Chemie, Berlin-Dahlem. Received 22 December 1938.
  5. Meitner, Lise; Frisch, O. R. (1939). "Disintegration of Uranium by Neutrons: a New Type of Nuclear Reaction". Nature . 143 (3615): 239–240. Bibcode:1939Natur.143..239M. doi:10.1038/143239a0. The paper is dated 16 January 1939. Meitner is identified as being at the Physical Institute, Academy of Sciences, Stockholm. Frisch is identified as being at the Institute of Theoretical Physics, University of Copenhagen.
  6. Frisch, O. R. (1939). "Physical Evidence for the Division of Heavy Nuclei under Neutron Bombardment". Nature. 143 (3616): 276. Bibcode:1939Natur.143..276F. doi:10.1038/143276a0. Archived from the original on 3 August 2004. The paper is dated 17 January 1939. [The experiment for this letter to the editor was conducted on 13 January 1939; see Rhodes, Richard (1986). The Making of the Atomic Bomb. Simon and Schuster. pp. 263 and 268.
  7. Otto R. Frisch, "The Discovery of Fission – How It All Began", Physics Today, V20, N11, pp. 43-48 (1967).
  8. J. A. Wheeler, "Mechanism of Fission", Physics Today V20, N11, pp. 49-52 (1967).
  9. "Fame without a Nobel Prize".
  10. http://www.birmingham.ac.uk/documents/culture/bookletfinalpdf.pdf
  11. Rhodes, Richard (1986). The Making of the Atomic Bomb. Simon and Schuster. pp. 612–613.
  12. 1 2 3 Frisch, Otto Robert (1980). What Little I Remember. Cambridge University Press. pp. 161–162. ISBN   0-52-128010-9. We were building an unusual assembly, with no reflecting material around it; just the reacting compound of uranium-235 ... For obvious reasons we called it the Lady Godiva assembly.
  13. Rhodes, Richard (1986). The Making of the Atomic Bomb. Simon and Schuster. pp. 610–11. ISBN   9780671441333.
  14. "Here Be Dragons".
  15. "Experiments with the Dragon Machine".
  16. 1 2 Otto Frisch, "What Little I Remember", Cambridge University Press (1979), ISBN   0-521-40583-1

Bibliography