Gamma Radiation in RaD and RaE Decay

By using chromatographically separated, carrier-free sources, the electromagnetic spectra of RaD and RaE have been investigated from 4 to 60 kev with an argon-methane gas proportional spectrometer. No gamma rays or $L$ x-rays were detected in the decay of RaE. Aside from the principal 46.5-kev transition, no gamma rays ($L$ x-rays (10 to 16 kev), a broad peak at about 31 kev appeared; it was established conclusively that in reality this is external beta-bremsstrahlung of RaE, whose low-energy region has been attenuated selectively so as to give the appearance of a gamma-ray peak.