Selection rules for beta and gamma particle transitions in strongly deformed nuclei

Institute “Rudjer Boškovič” and University of Zagreb, Zagreb, Croatia
Nuclear Physics (Impact Factor: 1.71). 08/1957; 4:625-631. DOI: 10.1016/0029-5582(87)90066-6


In the present paper we give a complete list of selection rules for beta and gamma particle transitions in strongly deformed nuclei. For the beta decay the list covers all transitions up to the second forbidden ones, while for the gamma decay the selection rules are given for the electric and magnetic dipole, quadrupole, and octupole transitions. This list represents a slight correction and enlargement of the selection rules already given in ref. 5). References to the papers making use of the selection rules in classifying nuclear states and explaining relative beta and gamma intensities are given at the end of the article.

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    ABSTRACT: General aspects of the problem of anomalous nuclear-structure-dependent contributions to the internal-conversion process are considered in conjunction with highly retarded electric or magnetic dipole transitions. Formulas for an elementary theory of anomalous internal conversion for E1 transitions are given. Selection rules for the relevant nuclear matrix elements are given in the quantu, numbers appropriate to spheroidally deformed nuclei . Similar selection rules for M1 transtions are given on the basis of the anomalous operators previously derived by Church and Weneser.
    Nuclear Physics 03/1958; 5(5):617-646. DOI:10.1016/0029-5582(58)90061-0 · 1.71 Impact Factor
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    ABSTRACT: The description of intrinsic states of deformed even-mass nuclei by the product wave functions of the strong coupling model, using Nilsson wave functions to describe the intrinsic particle configurations, is shown to lead to selection rules which depend on the coupling between the last two particles. In the case in which the coupling in the final and initial states is the same, the description leads, in the asymptotic limit of the Nilsson wave functions, to selection rules similar to those proposed earlier for odd-mass nuclei. For nuclear states with different relative couplings the selection rules lead most frequently to K-forbiddenness. It is shown that, if the non-transforming particle in the two-particle product wave function is not the same in the final and initial states, the resulting two-particle transition is formally forbidden. The experimental transition rates in even-mass nuclei to which definite configurations can be assigned are observed to fall within well-defined ranges characteristic of the degree of forbiddenness predicted by the selection rules. Furthermore, the data on log ft-values indicate that single-particle transitions occur with essentially the same speed whether the transforming particle is in an odd-mass or an even-mass nucleus.
    Nuclear Physics 05/1960; 16(2):215–230. DOI:10.1016/S0029-5582(60)81033-4 · 1.71 Impact Factor
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    ABSTRACT: The intrinsic level scheme calculated for a deformed nucleus by Nilsson has been used in conjunction with a single particle excitation model to compute the photonuclear electric dipole absorption cross section for Al27. The resultant curve contains peaks at 16, 18.5 and 21 MeV, in accord with the high resolution experimental results of Mihailovic. The calculated energy distribution of photoneutrons contains high energy direct emission groups, in agreement with experiment. Angular distributions computed also agree with experimental results. A new small cross section peak is predicted near 26 MeV.
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