#### Abstract

Expressions for the matrix element governing the emission of magnetic multipole radiation are given. The effect of weak configuration mixing and the small additional contribution to proton matrix elements (∼5%) arising from the nuclear spin-orbit interaction are considered. For $M4\mathrm{}$ transitions, even in nuclei near closed shells, the theoretical matrix elements derived from pure configurations are too large by a factor of two. The effect of configuration mixing reduces these. Choosing a $\delta $-function interaction of reasonable strength leads to a reduction of ∼25% in the matrix element for $1{g}_{\frac{9}{2}}\to 2{p}_{\frac{1}{2}}$ transition in ${}_{39}{}^{}{}_{}{}^{}\mathrm{Y}_{50}^{89}{}_{}{}^{}$. The ${\left(2\mathrm{}{p}_{\frac{1}{2}}\right)}^{-1\mathrm{}}\to {\left(1\mathrm{}{g}_{\frac{9}{2}}\right)}^{-1\mathrm{}}$ transition in ${}_{38}{}^{}{}_{}{}^{}\mathrm{Sr}_{49}^{87}{}_{}{}^{}$ is reduced close to the required 50%. The $1{h}_{\frac{11}{2}}\to 2{d}_{\frac{3}{2}}$ matrix element becomes ∼25% smaller. However, there are no data available for the nucleus ${}_{50}{}^{}{}_{}{}^{}\mathrm{Sn}_{65}^{115}{}_{}{}^{}$, with which one would like to make comparison. Finally, the ${\left(1\mathrm{}{i}_{\frac{13}{2}}\right)}^{-1\mathrm{}}\to {\left(2\mathrm{}{f}_{\frac{5}{2}}\right)}^{-1\mathrm{}}$ transition in ${}_{82}{}^{}{}_{}{}^{}\mathrm{Pb}_{125}^{207}{}_{}{}^{}$ has its matrix element reduced by only ∼6%. Although the reduction in ${}_{39}{}^{}{}_{}{}^{}\mathrm{Y}_{50}^{89}{}_{}{}^{}$ is somewhat too small, one cannot make a positive statement that configuration mixing is incapable of explaining the experimental result since a two-body force of a more realistic type may close the gap between theory and experiment. However, for ${}_{82}{}^{}{}_{}{}^{}\mathrm{Pb}_{125}^{207}{}_{}{}^{}$ there seems no doubt that other effects, for example, meson currents, must be incorporated.

DOI: http://dx.doi.org/10.1103/PhysRev.114.326

- Received 12 November 1958
- Published in the issue dated April 1959

© 1959 The American Physical Society