Beta Decay of Naturally RadioactiveIn115

A liquid scintillator loaded with indium has been used to study the fourth-forbidden beta decay of ${\mathrm{In}}^{115}$. Specific activity measurements yield a half-life of (6.9±1.5)×${10}^{14}$ years. A crude beta spectrum was obtained. Linear extrapolation of the Fermi-Kurie plot gives an end-point energy of 625±70 kev.