Decays of mass-separated ${}^{138}{Xe}$ and ${}^{138}{Cs}$

The

β

and subsequent

γ

decays of

{}^{138}{Xe}

and

{}^{138}{Cs}

were investigated using the on-line isotope separator system TRISTAN at the Ames Laboratory research reactor. Ge(Li)

γ

-ray singles and Ge(Li)-Ge(Li)

γ - γ

coincidence measurements were used to construct level schemes for

{}^{138}{Cs}

and

{}^{138}{Ba}

. For the decay of

{}^{138}{Xe}

, 94 of 99 observed

γ

-ray transitions have been placed in a level scheme for

{}^{138}{Cs}

with 27 excited states. For the decay of

{}^{138}{Cs}

, 82 of 86 observed

γ

rays are placed in a level scheme for

{}^{138}{Ba}

with 35 excited states. Ge(Li)-plastic coincidence measurements gave

Q

values of 2.83 ± 0.08 MeV and 5.29 ± 0.07 MeV for

{}^{138}{Xe}

and

{}^{138}{Cs}

, respectively. Spin and parity assignments have been deduced using

γ

-ray transition rates,

β

-decay

log ft

values, and other information existing in the literature. Interpretation of some of the energy levels is made from a shell-model viewpoint.

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Decays of mass-separatedXe138andCs138