Lifetime of the ($15/{2}_{1}^{-}$) state in 135Te

The lifetime of the (15/2(1)(-)) state of Te-135 has been measured to be tau = 809(22) ps, corresponding to a reduced transition rate of B(E2; 15/2(1)(-) -> 11/2(1)(-)) = 6.6(2) W.u. The experiment was performed at the focal point of the Lohengrin spectrometer and mu s-delayed gamma rays from mass-selected A = 135 ions were detected by four LaBr3(Ce) scintillators. This allowed the fast-timing technique to be used to access lifetimes in the 10s-of-ps to ns time region. The B(E2; 15/2(1)(-) -> 11/2(1)(-)) value is typical of a vibrational transition, despite Te-135 possessing only one valence neutron and two valence protons. Shell model calculations performed with the jj56pnb state-of-the-art effective interaction predict a B(E2) value close to the experimental one and show that contributions from the pi(g(7/2), d(5/2))nu f(7/2) couplings are coherent.