Gamma-Ray Studies of the Decays of ${\mathrm{Xe}}^{142}$, ${\mathrm{Cs}}^{142}$, ${\mathrm{Ba}}^{142}$, and ${\mathrm{La}}^{142}$

Measurements are reported for $\gamma$-ray energies and intensities present in the $\beta$ decays of four nuclei ${\mathrm{Xe}}^{142}$, ${\mathrm{Cs}}^{142}$, ${\mathrm{Ba}}^{142}$, and ${\mathrm{La}}^{142}$. These nuclei are all members of the isobaric decay chain beginning with ${\mathrm{Xe}}^{142}$, which was made available by use of an on-line isotope separator developed for the study of gaseous fission products. Partial energy level schemes have been constructed for ${\mathrm{Cs}}^{142}$, ${\mathrm{Ba}}^{142}$, ${\mathrm{La}}^{142}$, and ${\mathrm{Ce}}^{142}$ with the aid of Ge(Li)-Ge(Li) coincidence data. Some spin-parity assignments were made and relative transition probabilities determined for levels in ${\mathrm{Ba}}^{142}$ and ${\mathrm{Ce}}^{142}$; comparative half-lives were calculated for the decays of ${\mathrm{Ba}}^{142}$ and ${\mathrm{La}}^{142}$. The energy level scheme of ${\mathrm{Ce}}^{142}$ suggests vibration-like excitations, but that of ${\mathrm{Ba}}^{142}$ supports the suggestion of a transition to deformation effects as the neutron number approaches $N=88\mathrm{}$.