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Consequences of Charge Independence for Nuclear Reactions Involving Photons

Gell-Mann, Murray and Telegdi, Valentine L. (1953) Consequences of Charge Independence for Nuclear Reactions Involving Photons. Physical Review, 91 (1). pp. 169-174. ISSN 0031-899X. doi:10.1103/PhysRev.91.169.

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Some effects of the charge independence of nuclear forces on the emission and absorption of photons by light nuclei are investigated. It is found that the selection rules governing the change of isotopic spin T in such transitions are of practical importance in nuclei with T_z=0, particularly the rule that E1 transitions without change of isotopic spin are forbidden. Two examples of forbidden E1-emission (in N^(14) and O^(16)) are discussed, and detailed experimental reinvestigation is suggested in conection with each of them. The main consequence for photonuclear reactions of the aforementioned selection rule is that for each T_z=0 nucleus there is a threshold for (allowed) E1 absorption, corresponding to the first level with J=1−, T=1. For (γ, α)- and (γ, d)-reactions, where no isotopic spin can be carried off by the particle, E1 absorption can become effective only when there is enough energy to leave the residual nucleus in a T=1 state. The roles of E2 and M1 absorption, with and without change of isotopic spin, are discussed, and appropriate sum rules are derived. The rules governing (γ, α) processes are applied particularly to reactions in C^(12) and O^(16), where considerable experimental evidence is available and appears to support the theoretical conclusions.

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Additional Information:© 1953 American Physical Society. Received January 22, 1953. Published 1 July 1953. Work assisted in part by contract with the U.S. Office of Naval Research.
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Office of Naval Research (ONR)UNSPECIFIED
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Official Citation:Consequences of Charge Independence for Nuclear Reactions Involving Photons Murray Gell-Mann and Valentine L. Telegdi Phys. Rev. 91, 169 – Published 1 July 1953
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:60473
Deposited By: Ruth Sustaita
Deposited On:24 Sep 2015 21:05
Last Modified:10 Nov 2021 22:34

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