TRANSITION QUADRUPOLE-MOMENTS IN ZR-84

The high spin levels in Zr-84 have been populated through the Co-59(Si -28,p2n) reaction using 98 MeV Si-28 beam. Lifetime measurements for t he 20(+) and 22(+) levels in the yrast positive parity band using the line-shape analysis method gave values nearly a factor of 2.5 larger c ompared to those reported earlier-indicating a smaller deformation at high spins for Zr-84. The transition quadrupole moments obtained from the present measurements show a decrease at I similar to 8h and an inc rease at I similar to 16h. Theoretical calculations using the Nilsson model with the Woods-Saxon potential show that this decrease (increase ) is directly related to the 2p (2n) alignment in high (low) Omega orb itals.