The radiations from ${\mathrm{Re}}^{186}$ have been studied by means of beta-ray spectrometers and scintillation counting techniques. It has been found that ${\mathrm{Re}}^{186}$ decays both by beta-emission and by $K$-capture. Three partial beta-ray spectra of 1.07-, 0.93-, and 0.3-Mev maximum energies have abundances of 76, 19, and 0.4 percent, respectively, and lead to the ground state and 137- and 627-kev excited states of ${\mathrm{Os}}^{186}$. Two $K$-capture branches of 3 and 2 percent abundances lead to the ground state and a 123-kev excited state of ${\mathrm{W}}^{186}$. Transitions between these states give rise to electric quadrupole gamma-rays of 137 and 123 kev and other relatively weak magnetic dipole gamma-rays of 764- and 627-kev energy. A decay scheme in which spins and parities are assigned to all the levels is proposed.

• Received 8 February 1951

DOI:https://doi.org/10.1103/PhysRev.82.646