Disintegration of cerium of mass 144.

A study of the beta decay of 275 day Ce144 and its daughter 17.5 min. Pr144 , has been made using a thin lens magnetic spectrometer. Analysis of the beta-spectrum Indicates the presence of five spectra with end-points at 3.06 ± 0.09, 1.05 ± 0.05, 0.517 ± O.O36, 0.303 ± 0.020, and 0.179 ± 0.015 Mev. The first three have been assigned to Pr1 , the remaining two to Ce1 . Conversion lines at 90.1 ± 0.9 and 125 ± 1.3 Kev. are attributed to internal conversion of a 132 Kev. gamma-ray following the 0.179 Mev. beta-disintegration of Ce144 . Measurement of gammaray energies by spectrometric methods proved Impractical with the activity available, but absorption methods reveal three other gamma-rays of energies about 2, 0.5 and 0.22 Mev. The results of coincidence experiments are, on the whole, inconclusive, but indicate in general the complexity of the spectra. Tentative disintegration schemes are presented.