The Beta- and Gamma-Radiations fromCopper64andEuropium152

The beta- and gamma-radiations from ${\mathrm{Cu}}^{64}$ and ${\mathrm{Eu}}^{152}$ have been studied with the aid of a magnetic spectrometer of high resolution. Copper emits both positrons and electrons with a maximum energy of 0.659±0.003 and 0.578±0.003 Mev, respectively. The effect on the shape of the spectra of scattering within the source was investigated. The spectra obtained with an extremely thin source were found to contain fewer low energy particles than those obtained with a thicker source. The thin source results in much better agreement with the original Fermi theory of beta-decay than with the later modification introduced by Konopinski and Uhlenbeck. As the source is made thicker there is a gradual change in the shape of the spectra which eventually brings about better agreement with the K-U theory than with the Fermi theory. Eu emits electrons with a maximum energy of 1.885±0.012 Mev and several gamma-rays. The energies of three of the gamma-rays have been determined as 0.123±0.001, 0.163±0.001 and 0.725±0.003 Mev.