| Revision as of 01:24, 23 June 2009 editAbd (talk | contribs)14,259 editsm missing word← Previous edit | Revision as of 01:31, 23 June 2009 edit undoජපස (talk | contribs)Extended confirmed users, Pending changes reviewers, Rollbackers60,450 edits The Coulomb barrier, in general, is what is overcome. It's only the one predicted by the Bohr Model which is wrong. See talk.Next edit → | ||
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| In this process the ] half of an energetic ] fuses with a target ], transmuting it to a heavier ], while the ] half is ejected. An example would be the ] of ] to ]. | In this process the ] half of an energetic ] fuses with a target ], transmuting it to a heavier ], while the ] half is ejected. An example would be the ] of ] to ]. | ||
| The process is considered important because it allows a nuclear interaction to take place at energies insufficient to directly penetrate the ], due to a polarization of the deuteron where the proton-end faces away from the incident nucleus and the neutron-end faces towards the incident nucleus during the most energetically favorable arrangement for the reaction.<ref name=friend68 /> | The process is considered important because it allows a nuclear interaction to take place at energies insufficient to directly penetrate the ] expected from the ], due to a polarization of the deuteron where the proton-end faces away from the incident nucleus and the neutron-end faces towards the incident nucleus during the most energetically favorable arrangement for the reaction.<ref name=friend68 /> | ||
| == History == | == History == | ||
Revision as of 01:31, 23 June 2009
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The Oppenheimer–Phillips process or strip reaction is a type of deuteron-induced nuclear reaction.
In this process the neutron half of an energetic deuteron fuses with a target nucleus, transmuting it to a heavier isotope, while the proton half is ejected. An example would be the nuclear transmutation of carbon-12 to carbon-13.
The process is considered important because it allows a nuclear interaction to take place at energies insufficient to directly penetrate the Coulomb barrier expected from the Bohr model, due to a polarization of the deuteron where the proton-end faces away from the incident nucleus and the neutron-end faces towards the incident nucleus during the most energetically favorable arrangement for the reaction.
History
Explanation of this effect was published by J. Robert Oppenheimer and Melba Phillips in 1935, considering experiments with the Berkeley cyclotron showing that some elements became radioactive under deuteron bombardment.
Mechanism
The Coulomb barrier sets the requisite energy that interacting atomic nuclei need to fuse. Since nuclei are always positively charged the electrostatic force is always repulsive. However, for neutrons themselves, since they have no charge, there is no Coulomb barrier.
During the O-P process, the deuteron's positive charge is spatially polarized, as if at one end of a barbell, the proton end. When a deuteron approaches the target nucleus, the proton is repelled by the electrostatic field until, assuming the incident energy is not sufficient for it to surmount the barrier, the proton approaches to a minimum distance, having climbed the Coulomb barrier as far as it can. If the deuteron is close enough for the strong nuclear force, which only operates over very short distances, to exceed the repulsive electrostatic force, fusion with the target nucleus may begin.
In the O-P process, as the neutron is drawn to the target nucleus, the deuteron binding force exerted by it pulls the proton closer than it would otherwise have approached on its own, increasing the potential energy of the proton. If the neutron is captured, the proton is stripped from it and is ejected. The proton at this point is able to carry away more than the incident kinetic energy of the deuteron since it has approached the target nucleus more closely than what is possible for an isolated proton with the same incident energy. In such instances, the transmuted nucleus is left in an energy state as if it had fused with a neutron of negative kinetic energy.
References
- ^ Friendlander, 2008, p. 68-69
- Oppenheimer, 1995, page 192 cf. Note on the transmutation function for deuterons, J. Robert Oppenheimer and Melba Phillips, Phys. Rev. 48, September 15, 1935, 500-502, received July 1, 1935.
- Blatt, 1991, pp. 508-509
- Blatt, 1991, pp. 508-509
- J. Robert Oppenheimer (1995). Alice Kimball Smith, Charles Weiner (ed.). Robert Oppenheimer: Letters and Recollections (reimpressed, illustrated ed.). Stanford University Press. ISBN 0804726205, 9780804726207.
{{cite book}}: Check|isbn=value: invalid character (help) - Gerhart Friedlander (1949). Introduction to Radiochemistry. John Wiley And Sons. ISBN 1443723096, 9781443723091.
{{cite book}}: Check|isbn=value: invalid character (help) - M. Blatt, John (1991). Theoretical Nuclear Physics (illustrated ed.). Courier Dover Publications. pp. 505–516. ISBN 0486668274, 9780486668277.
{{cite book}}: Check|isbn=value: invalid character (help); Unknown parameter|coauthor=ignored (|author=suggested) (help)
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