High-K,t1/2=1.4(1) ms, isomeric state in Lr255

An isomeric state in 255 Lr with a half-life of t ½ = 1.4(1) ms and E x > 720-keV has been observed for the first time using the GABRIELA setup at the focal plane of the VASSILISSA separator. Based on its K-forbiddeness, the configuration of the state is most probably formed by coupling the valence proton to a two quasiparticle neutron excitation. Possible three quasiparticle configurations are discussed.