Beta Decay of Thulium-171

Abstract

The radiations emitted in the decay of 1.9-year ${\mathrm{Tm}}^{171}$ have been studied with a 180°, 40-cm radius of curvature, shaped magnetic-field spectrometer, a scintillation spectrometer, and a 125-gauss permanent-field spectrograph. Beta-gamma coincidence measurements have also been made. Two beta groups with end-point energies of 96.5±1 kev and ∼30 kev were observed. A 66.7±0.5 kev transition, probably an $M1-E2\mathrm{}$ mixture, was also observed. Possible spin assignments are discussed.