Enhancement of M1 transition rates at high spin in Mo-90

High spin states in Mo-90 have been populated through the Co-59 (Cl-35,2p2n ) Mo-90 reaction at a beam energy of 116 meV. Level Lifetimes of the positi ve-parity decay sequence are measured by using the Doppler shift attenuatio n method. It is observed that the M1 transition strengths show a substantia l enhancement at high spin. This behaviour may be related to occupation of high Omega orbitals by a pair of g(9/2) protons. A deformed, oblate, shape is suggested above the 13(+) state.