Isomers and high-spin structures in the N=81 isotones Xe-135 and Ba-137

© 2017 American Physical Society. The high- spin structuresand isomers of the N=81 isotonesXe135 and Ba137 are investigated after multinucleon-transfer (MNT) and fusion-evaporation reactions. Both nuclei are populated (i) in Xe136+U238 and (ii) Xe136+Pb208 MNT reactions employing the high-resolution Advanced Gamma Tracking Array ( AGATA) coupled to the magnetic spectrometer PRISMA, (iii) in the Xe136+Pt198 MNT reaction employing the γ-ray array GAMMASPHEREin combination with the gas-detectorarray CHICO, and (iv) via a B11+Te130 fusion-evaporation reaction with the HORUS γ-ray array at the University of Cologne. The high-spin level schemesof Xe135 and Ba137 are considerably extended to higher energies. The 2058-keV (19/2-) state in Xe135 is identified as an isomer, closing a gap in the systematics along the N=81 isotones. Its half-life is measured to be 9.0(9) ns, corresponding to a reduced transition probability of B(E2,19/2-→15/2-)=0.52(6) W.u. The experimentally deduced reduced transition probabilities of the isomeric states are compared to shell-modelpredictions. Latest shell-modelcalculations reproduce the experimental findings generally well and provide guidance to the interpretation of the new levels.