Levels and transitions in ¹⁴⁰Ba populated following the β decay of ¹⁴⁰Cs

Levels in ¹⁴⁰Ba were populated following the beta decay of ¹⁴⁰Cs (T₁2/=64 s) which was produced by the online fission product mass separator OSTIS at the Institut Laue-Langevin. Gamma data were recorded in an event-by-event mode and the coincidence results enable a decay scheme with 52 levels up to 5.8 MeV to be established. Directional correlation measurements were made on 14 direct cascades and 11 skip cascades, all in coincidence with the 2₁⁺ to 0₁⁺ ground state transition. Definite spin assignments were made for 14 levels and tentative assignments for 5 levels, with multipole mixing ratios being extracted where applicable. In addition, approximate log ft values were calculated for all the beta -fed levels and these, together with the relevant modes of decay, were used as a bias for tentative assignments for all but two of the levels not studied using the correlation technique. The experimental data for the neutron-rich barium isotopes ^140-146Ba have been fitted using IBM-2 and the 2⁺ level at 1994 keV in ¹⁴⁰Ba is identified as a mixed-symmetry state.