High spin states in 89Y

States of 89Y, populated through the 87Rb(α,2n) reaction in the energy range Esub(α)=30 to 55 MeV, were studied using in-beam γ-ray spectroscopy techniques. Excitation functions, γ-ray angular distributions and γ-γ coincidences were measured. Nine hitherto unknown states above 3.3 MeV were found and their decay modes were determined. These levels are tentatively assigned spin values from I=13/2 up to 23/2. Their energies are found to be close to those obtained from coupling the 3-, (5)-, (6)- and (7)- states of the 88Sr core with the single-particle 9/2+ isomeric state at 908.8 keV. The validity of a weak coupling description for these high spin states is further supported by the similarities with the known 87Sr data. The analogy with 87Sr seems however to breakdown regarding the I=15/2 highest spin member of the [3-Xgsub(9/2)] multiplet. This state appears to lie significantly higher in 89Y. The data confirm the previous information existing on levels below 3.3 MeV, with the exception of a level found at 2894.3 keV and for which a tentative I=13/2+ assignment is proposed. (Auth.)