Article

# 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 **ABSTRACT**

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. -
##### Article: Der Zerfall des Gd153

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**ABSTRACT:**The electron capture decay of Gd153 was studied by mounting the radioactive source in three different ways: Outside or in the center or built in in the lattice of a NaJ (Tl)-crystal. The PL+M+/PK-capture ratio was measured for the disintegration into the 975 resp. 103 keV level and into the 1725 level of Eu153: 034002 and 08503. These results were used to determine the disintegration energy of Gd153: 27958 kev and 269 –16 +26 keV. Moreover, branching ratios, log ft-values and conversion coefficients were determined. - [Show abstract] [Hide abstract]

**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.

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