IDENTIFICATION AND STRUCTURE OF HIGH-SPIN PARTICLE-HOLE STATES IN MO-89

Particle-gammagamma and gammagamma-coincidences of the reaction Ni-58(Ar-36, 4 pn)89Mo have been used to gain more information about high spin states in 89Mo and to establish the yrast sequence up to 7.6 MeV excitation energy and probable spin 37/2 h. Spins and parities were assigned on the basis of DCO-ratios measured with the OSIRIS spectrometer and a large volume Ge detector placed at 162-degrees to the beam. Furthermore, a gamma-ray angular distribution experiment was carried out using the reaction Ni-58(Cl-35, 3 pn)89Mo. As in the neighboring isotopes 88Mo and Mo-90, the positive-parity high-spin states can be grouped into shell model multiplets characterized by increasing seniorities of proton particles and neutron holes in the 1 g9/2 shell. The negative-parity states can be explained with one nucleon moving in the P1/2 orbit. The energies and wave functions of these states have been deduced by means of the shell model code RITSSCHIL. The 2584 keV (21/2+) is an isomeric state the mean life of which has been estimated from delayed gammagamma-coincidences.