Evolution From Spherical Single-Particle Structure To Stable Triaxiality At High Spins In Nd-140

The level structure of Nd-140(60)80 has been established up to spin 48 by in-beam gamma-ray spectroscopy by use of the Zr-96(Ca-48, 4n) reaction. High-fold gamma-ray coincidences were measured with the EUROBALL spectrometer. Twelve new rotational bands have been discovered at high spins. They are interpreted as being formed in a deep triaxial minimum at epsilon(2) approximate to 0.25 and gamma approximate to 35(degrees). Possible configurations are assigned to the observed bands on the basis of configuration-dependent cranked Nilsson-Strutinsky calculations.