Decay of the 25-min Activity ofTe131

The decay of the 25-min activity of ${\mathrm{Te}}^{131}$ has been investigated with scintillation spectrometers and also with an intermediate image beta-ray spectrometer. The energies of the gamma rays which have been observed are 145, 350, 445, 490, 590, 650, 930, 985, 1130, and 1280 keV. On the basis of gamma-gamma coincidence measurements, it is proposed that the 350-, 930-, and 985-keV gamma rays are doublets of gamma rays with energies close to each other. The observed coincidences are explained by proposing levels at 145, 490, 590, 1065, 1130, 1425, and 1480 keV. The total absorption gamma-ray spectrum and sum-coincidence spectra have also been studied to confirm these levels and their decay modes. Spin and parity assignments have been made to these levels on the basis of the $log\mathrm{ft}$ values of the beta transitions feeding them and also their decay modes.