Determination of gamma ray energies and abundances ofTh229

Gamma-ray energies and intensities in the alpha decay of ${}_{}{}^{229}{}_{}{}^{}\mathrm{Th}$ were precisely determined using a high-resolution Ge detector. Twenty new gamma rays were observed whereas 16 gamma rays earlier reported could not be observed. A modified energy level diagram for ${}_{}{}^{225}{}_{}{}^{}\mathrm{Ra}$ is proposed using the present results.