Beta Spectrum ofTl206

The spectrum shape of the $\beta$ particles emitted in the $0^{-}\to 0^{+}$ decay of ${}_{}{}^{206}{}_{}{}^{}\mathrm{Tl}$ was determined using a $4\pi$ solid-state $\beta$ spectrometer. The sources used were isotopically separated and extremely thin. The shape factor shows only small deviations from a statistical form. The half-life was determined as ${\tau }_{\frac{1}{2}}=4.27\mathrm{}\pm 0.05$ min.