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Small deviations from the statistical shape which has previously been reported for Pr 143 might be expected from a theoretical prediction for such a once-forbidden nonunique transition. The spectrum was investigated with greater precision and in greater detail than in past studies, with magnetic and scintillation spectrometers. The spectrum is found to exhibit small deviations from a statistical shape. The spectrum can be fitted with a once-forbidden, nonunique shape factor.

The conversion electron spectra arising from electron-capture decay of Am 239 and Am 240 have been studied with a 180° photographic spectrograph at ^0.1% resolution. The Am 239 spectrum and the multipolarity data obtained therefrom are similar to those observed from the beta decay of Np 239 , but the electron intensity data indicate somewhat different relative populations of the Pu 239 excited states in the two cases. An attempt to assign the spin and parity of Am 239 from // values by the use of AI and AK selection rules does not give a consistent explanation.The energies of the first two excited states of Pu 240 are accurately measured, and from these values (42.87±0.04 and 141.77=b0.2 kev) the constants in the Bohr-Mottelson two-term rotational formula are evaluated: 4 = 7.16±0.01 kev, 5 = 0.005^0.002 kev.