Abstract
The decay of mass-separated Cs141 produced in thermal neutron fission of U235 was studied by x-ray and γ-ray spectroscopy. The level scheme deduced for the N=85 isotone Ba141 differs substantially from previous level schemes. A new 72- level at 55.0 keV was established as the second-excited state, completing the triplet of low-lying 32-, 52-, and 72- states expected for this "quasi-f72" nucleus. For transitions among these levels, values of |δ|(E2M1) were deduced. Comparisons are made with level structures of other N=85 isotones. Systematic trends in energies of states characteristic of quasi-f72 nuclei are discussed. RADIOACTIVITY Cs141 [from U235(n,f)]; measured Eγ, Iγ, γγ coin., HpGe and Ge(Li) detectors; Ba141 deduced levels, J, π, logft, |δ|(E2M1). Mass-separated Cs141 activity. © 1982 The American Physical Society.