Otto Robert Frisch

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O. R. Frisch
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Otto Robert Frisch
Atomic bomb
AwardsFellow of the Royal Society[1]
Scientific career
FieldsPhysics
Signature

Otto Robert Frisch

atomic bomb in 1940.[2]

Early life

Frisch was born in

Jewish family, the son of Justinian Frisch, a painter, and Auguste Meitner Frisch, a concert pianist.[3] 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.

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.[4]

The accession of

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.

Nuclear fission

Main article: Discovery of nuclear fission
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, and estimated the energy released, and Frisch coined the term fission, adopted from a process in biology, to describe it.[6][7]

Political restraints of the Nazi era forced the teams of Hahn and Strassmann 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.[8] Meitner's and Frisch's paper explained the physics behind the phenomenon.[9]

Frisch went back to Copenhagen, where he was quickly able to isolate the pieces produced by fission reactions.[10] As Frisch himself later recalled, a fundamental idea of the direct experimental proof of the nuclear fission was suggested to him by George Placzek.[11][12] Many feel that Meitner and Frisch deserved Nobel Prize recognition for their contributions to understanding fission.[13]

In mid-1939 Frisch left Denmark for what he anticipated would be a short trip to

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.[14] He went to America in 1943 having been hurriedly made a British citizen
.

Manhattan Project

Main article: Manhattan Project
Complex scientific apparatus with metal frame surrounding three sections of a sphere held in the center by a system of rods, and separated vertically from one another so as to form a complete sphere when brought together
The Godiva device at Los Alamos

In 1944 at

Lady Godiva assembly".[16] 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'.[16] 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".[16] "In two seconds he received, by the generous standards of the time, a full day's permissible dose of neutron radiation."[17] 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.[18] 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.[19]

Return to England

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[5] and a fellow of Trinity College.

Before he retired he designed[20] 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 Laser-Scan Engineering Ltd., to exploit the idea.

Retirement

University of Birmingham - Poynting Physics Building - blue plaque

He retired from the chair in 1972 as required by University regulations.[20] He died on 22 September 1979.[5]

References

  1. ^
    JSTOR 769874
    .
  2. doi:10.1063/1.2913924. Archived from the original
    on 28 September 2013.
  3. ^ "Otto Robert Frisch | Biography & Facts". Encyclopedia Brittanica. Retrieved 21 December 2023.
  4. S2CID 120793548
    .
  5. ^
    ISBN 978-0-684-86315-3
    . Retrieved 4 December 2021.
  6. ISBN 978-1-61234-890-2
    .
  7. OCLC 13793436
    .
  8. S2CID 5920336
    . The authors were identified as being at the Kaiser-Wilhelm-Institut für Chemie, Berlin-Dahlem. Received 22 December 1938.
  9. S2CID 4113262
    . 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.
  10. S2CID 4076376. 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.
  11. ^ Otto R. Frisch, "The Discovery of Fission – How It All Began", Physics Today, V20, N11, pp. 43-48 (1967).
  12. ^ J. A. Wheeler, "Mechanism of Fission", Physics Today V20, N11, pp. 49-52 (1967).
  13. ^ "Fame without a Nobel Prize". 5 November 2015.
  14. ^ "Culture trails – Blue Plaque Guide" (PDF). University of Birmingham. Retrieved 4 December 2021.
  15. ^ Rhodes, Richard (1986). The Making of the Atomic Bomb. Simon and Schuster. pp. 612–613.
  16. ^
    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.
  17. ISBN 9780671441333
    .
  18. ^ "Here Be Dragons".
  19. S2CID 108799363. {{cite journal}}: Cite journal requires |journal= (help
    )
  20. ^
    ISBN 0-521-40583-1

Bibliography

  • Atomic Physics Today (1961)
  • Working with ATOMS (1965)
  • What Little I Remember (1979)

External links

Wikimedia Commons has media related to Otto Frisch.
Academic offices
Preceded by Jacksonian Professor of Natural Philosophy
1947–1972 		Succeeded by
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