Internal Bremsstrahlung and Ionization Accompanying Beta Decay

Internal bremsstrahlung spectra from ${\mathrm{S}}^{35}$ and ${\mathrm{Pm}}^{147}$ have been investigated with the NaI scintillation spectrometer. Both the absolute cross section of production and the energy distribution agree with theoretical predictions. The theoretical internal bremsstrahlung spectrum of RaE was calculated by using both the observed forbidden $\beta$ spectrum and an allowed $\beta$ distribution. No significant differences in shape were found in these two cases except in the absolute cross section of production.