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George Placzek asked Bohr why uranium seemed to fission with both very fast and very slow neutrons. Walking to a meeting with Wheeler, Bohr had an insight that fission at low energies was due to the uranium-235 isotope, while at high energies it was mainly due to the far more abundant uranium-238 isotope. [24] They co-wrote two more papers on ...
When Bohr began his work on a new atomic theory in the summer of 1912 [8]: 237 the atomic model proposed by J J Thomson, now known as the Plum pudding model, was the best available. [ 9 ] : 37 Thomson proposed a model with electrons rotating in coplanar rings within an atomic-sized, positively-charged, spherical volume.
George Placzek asked Bohr why uranium fissioned with both very fast and very slow neutrons. Walking to a meeting with Wheeler, Bohr had an insight that the fission at low energies was due to the uranium-235 isotope, while at high energies it was mainly due to the far more abundant uranium-238 isotope. [120]
Nuclear fission is an extreme example of large-amplitude collective motion that results in the division of a parent nucleus into two or more fragment nuclei. The fission process can occur spontaneously, or it can be induced by an incident particle."
The first theoretical description of nuclear pairing was proposed at the end of the 1950s by Aage Bohr, Ben Mottelson, and David Pines (which contributed to the reception of the Nobel Prize in Physics in 1975 by Bohr and Mottelson). [15] It was close to the BCS theory of Bardeen, Cooper and Schrieffer, which accounts for metal superconductivity ...
The liquid-drop model was first proposed by George Gamow and further developed by Niels Bohr, John Archibald Wheeler and Lise Meitner. [3] It treats the nucleus as a drop of incompressible fluid of very high density, held together by the nuclear force (a residual effect of the strong force ), there is a similarity to the structure of a ...
Niels Bohr and John Wheeler had theorized that heavy isotopes with odd atomic mass numbers were fissile. If so, then plutonium-239 was likely to be fissile. [ 42 ] In May 1941, Emilio Segrè and Glenn Seaborg produced 28 μg of plutonium-239 in the 60-inch (150 cm) cyclotron at the University of California, Berkeley and found that it had 1.7 ...
The Wheeler–Feynman absorber theory (also called the Wheeler–Feynman time-symmetric theory), named after its originators, the physicists Richard Feynman and John Archibald Wheeler, is a theory of electrodynamics based on a relativistic correct extension of action at a distance electron particles. The theory postulates no independent ...