Prompt and delayed spectroscopy of Tb142 using recoil-isomer tagging

Recoil-isomer tagging has been used to characterize the states built upon an I-pi=8(+) isomer in Tb-142. High-spin states of the neutron-deficient nucleus Tb-142 were populated using an Fe-54 beam, accelerated onto a Mo-92 target of thickness similar to 500 mu g/cm(2) at energies of 245, 252, and 265 MeV using the K130 cyclotron at the University of Jyvaskyla, Finland. Use of the JUROGAM target-position Ge-detector array coupled with the GREAT focal-plane spectrometer at the RITU gas-filled recoil separator has significantly increased the efficiency of the isomer-tagging technique. The rotational band built upon the I-pi=8(+) isomeric state was established with isomer-tagged gamma-gamma coincidence data and angular distributions were measured for some of the more intensely populated states. Two previously unobserved bands that bypass the isomer were also established. The new data have been interpreted within the framework of the cranked-shell model. The data show good agreement with the calculated triaxial nuclear shape with gamma=-30(degrees) for the Tb-142m2 isomeric state. The B(M1)/B(E2) branching ratios, nuclear alignment, signature splitting, and reduced transition probability, B(E1), of the isomeric state have been systematically compared with those of the neighboring nuclei. These comparisons give further evidence for the pi h(11/2)circle times nu h(11/2) configuration of the isomer.