Spin-dependent triaxial deformation in neutron-rich mo isotopes

The Eurogam-2 array has been used to study γ rays emitted following the spontaneous fission of a 248Cm source. Analysis of Doppler-broadened line shapes corresponding to decays from excited rotational states in neutron-rich Sr, Zr, and Mo fission fragments has enabled the first measurements of state lifetimes in these nuclei at around I = 10. The results are consistent with a predicted rotation-induced change in the triaxiality of the yrast states of the Mo isotopes that contrasts with the more stable behavior observed in the Zr and Sr nuclei. © 1996 The American Physical Society.