LIFETIME OF THE 3(1)- STATE AND OCTUPOLE COLLECTIVITY IN ZR-96

The half-life of the 1897.2-keV, 3(1)- state in Zr-96 has been measure d as (67.8 +/- 4.3) ps using the recoil-distance technique following i nelastic excitation by 105-MeV S-32 ions. This is equivalent to a life time which is about 40% longer than those reported from two recent cen troid-shift measurements. Our lifetime implies B(E3)up = (0.180 +/- 0. 018) e2b3, i.e., (47.1 +/- 4.7) W.u., which is the most enhanced one-p honon g.s. --> 3(1)- transition strength observed in nuclei. A recent quasiparticle random-phase approximation (QRPA) calculation reproduces our result. Serious doubts are raised about an earlier conclusion tha t the reduced octupole transition probabilities of ''mirror'' nuclei c orrespond to the harmonic low for small amplitude vibrations. The enha nced B(E1:3(1)- --> 2(1)+) = (1.71 +/- 0.11) 10(-5) e2b deduced from t he present work is consistent with appreciable octupole deformation. T he measured B(E3)up resolves problems in the interpretation of the iso spin character of the E3 transition derived from inelastic scattering data.