Decay ofEr171

The decay of ${\mathrm{Er}}^{171}$ (7.52 hours) has been studied with beta- and gamma-scintillation spectrometers, a magnetic lens spectrometer, and a 180° permanent-magnet spectrograph. A number of previously unobserved beta-ray and gamma-ray transitions were found. On the basis of coincidence studies, intensity data, internal conversion coefficients, and the measured transition energies, a consistent level scheme for ${\mathrm{Tm}}^{171}$ is proposed which has excited states at energies of 0.0051, 0.1167, 0.1291, 0.4251, 0.636, 0.688, 0.744, 0.921, and 1.008 Mev. The observed states are identified with appropriate orbitals of the Nilsson energy level diagram, and the experimental transition probabilities are examined in terms of the asymptotic selection rules for strongly deformed nuclei.