The exotic nuclear decay of ${}_{}{}^{223}{}_{}{}^{}\mathrm{Ra}$ by emission of ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$ nuclei has been investigated by use of an intense radioactive ${}_{}{}^{227}{}_{}{}^{}\mathrm{Ac}$ source and a magnetic spectrometer with a large solid angle. After a run of 5 d, a group of eleven events was observed at the expected location of ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$ in a $\Delta E-E$ telescope calibrated with a ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$ beam. A branching ratio of (5.5 ± 2.0) × ${10}^{-10\mathrm{}}$ was measured for the emission of ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$ nuclei relative to $\alpha$ particles from ${}_{}{}^{223}{}_{}{}^{}\mathrm{Ra}$ in agreement with the previously reported ratio of (8.5 ± 2.5) × ${10}^{-10\mathrm{}}$.

• Received 8 June 1984

DOI:https://doi.org/10.1103/PhysRevLett.53.759