High-spin structures of La-138(57)81

Odd-odd La-138 nuclei have been produced in the C-12+U-238 fusion-fission reaction and their. rays studied with the Euroball array. The high-spin level scheme has been built up to similar to 4.5 MeV excitation energy and spin I similar to 16 similar to from the triple gamma-ray coincidence data. An isomeric state lying at 739-keV excitation energy has been identified. The configurations of the structures are first discussed by analogy with the proton excitations identified in the semimagic La-139(82) nucleus, which involve the three high-j orbits lying above the Z = 50 gap, pi g(7/2), pi(5/2), and pi h(11/2). The competition of these three orbits to produce the yrast line is confirmed by the results of shell-model calculations performed in this work