Internal Pair Conversion inMg24

The positron spectra from the internal pair conversion of the two $\gamma$-rays following the ${\beta }^{-}$ decay of ${\mathrm{Na}}^{24}$ have been observed, and the internal pair conversion coefficients found to be 7.1×${10}^{-4\mathrm{}}$ in the case of the 2.758-Mev $\gamma$-ray and 0.6×${10}^{-4\mathrm{}}$ in the case of the 1.380-Mev $\gamma$-ray. The value of the coefficients and the shape of the spectra lead to the conclusion that both $\gamma$-rays are electric quadrupole transitions.