Radiations fromW185andW187

The radiations of ${\mathrm{W}}^{185}$ and ${\mathrm{W}}^{187}$ have been examined in a thin-lens magnetic spectrometer, by coincident scintillation spectrometers, and with a gray-wedge analyzer. ${\mathrm{W}}^{185}$ was found to emit no detectable gamma rays. Its beta spectrum is first-forbidden ($\Delta I=1\mathrm{}$ yes!) and of maximum energy 440±5 kev. By observation of internal conversion lines and photoelectric peaks, fourteen gamma rays have been resolved in the decay of ${\mathrm{W}}^{187}$. Three beta-ray spectra are emitted with end-point energies of 340±20, 630±10, and 1325±15 kev with relative intensities of 10%, 70%, and 20%. The most energetic spectrum has the unique shape associated with a spin change of two and a change of parity.