Transition probabilities between high spin states in 88Mo and 90Mo.

Abstract

The reactions (Ni(Ar, alpha2p)Mo)-Ni-58-Ar-36-Mo-88 and (Ni(Ar, 4p)Mo)-Ni-58-Ar-36-Mo-90 at 149 and 140 MeV beam energies have been used to carry out Doppler shift attenuation and recoil distance lifetime measurements and to determine DCO ratios in Mo-88 and Mo-90. A singles angular distribution experiment using the reaction (Ni(Cl, 3p)Mo)-Ni-59-Cl-35-Mo-90 has been performed at 120 MeV beam energy to measure spin assignments in Mo-90 and to calibrate the DCO analyses for both nuclei. Reduced transition probabilities for more than 60 transitions in Mo-88, Mo-90 have been deduced. The extensive data set is incorporated in a detailed comparison between the two nuclei and, for Mo-90, with predictions from shell model calculations within a restricted pi(p1/2), pi(99/2), nu(p1/2), and nu(g9/2) configuration space and with different residual interaction parameters. The electromagnetic properties of the negative parity states of Mo-90 are well reproduced by the calculations while the positive parity states show hints of seniority mixing at intermediate spins.