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The decay of M Am has been studied by observing a-y coincidences using Si (Au) surface-barrier and Ge (Li) detectors in conjunction with a 4096-channel two-parameter analyzer, y rays of 31.2, 43.6, 50.6, 55.4, 74.8, 86.7, 117.8, 142.0, 169, 195, and 220 keV were observed. Only the 43.6-, 74.8-, and 117.8-keV y rays have been previously reported. These results confirm many features of the previously accepted level scheme of the 239 Np daughter. Furthermore, new levels at 72 and 123 keV have been found which are apparently the f-f and ^+ members, respectively, of the ground-state rotational band. These energies agree well with predictions based on the collective model. The intensity ratio of a groups to the ground and first excited states has been measured to be 1.17, in poor agreement with a theoretical estimate of 2.03.

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A praseodymium isotope with a half-life of 75 min has been assigned to 137 Pr. It decays with a iC-captureto-positron ratio of 2.5±0.2 and a maximum positron energy of 1.74±0.05 MeV. Approximately 6% of the disintegrations are to excited states of 137 Ce. The energies and intensities of 28 gamma-ray transitions were measured with a Ge(Li) detector. Coincidences of the gamma rays were measured using two 3-in. Nal(Tl) crystals and a multiparameter analyzer. An energy-level diagram consistent with the observed gamma-ray energies, intensities, and coincidences has been deduced.

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A precision study of the decay of 134CSg and ~ 34Cs" has been made, using ordinary Ge(Li) spectrometers and a Compton-suppression spectrometer. The logft value of the second forbidden nonunique fl-decay to 134Xe has been measured to be 13.0_+0.2. The M4 7-ray transition in 13~Csm(8-) decay has been measured to have c~K= 73 + 7 and a hindrance of 7.0 over the Moskowski estimate. This is discussed in terms of the level configurations and the analogous transition in ~33Xe. A new intensity limit of 2 x 10 -6 has been set for the zero-phonon transition between the 4 + and 2 + members of the two-phonon triplet. This leads to an upper limit for B(E2)4~2, greater than 905. This and the more precise 7-ray intensity values are discussed in relation to presently available nuclear models.Radioactivity 134Cs and ~34Csm. Measured E~, I~,, 134Ba, 13'~Cs deduced levels.