Enhanced deformation in light Pr nuclei

We observe for the first time rotational bands of enhanced deformation (ED) in (127)pr and (128)pr, and suggest that these bands are built upon pi g(9/2) ([404](9/2)) in Pr-127 and on the pi g(9/2)upsilon h(11/2) orbitals in Pr-128. These are the lightest isotopes of Pr for which ED bands have been observed. A contrasting trend in the dynamical moments of inertia (J((2))) versus N is observed at low frequencies for the "normal-deformed" pi h(11/2) and "enhanced-deformed" pi g(9/2) bands of Pr127-131 both experimentally and in self-consistent Woods-Saxon calculations. The trends in J((2)) and beta(2) are correlated with a decreasing probability for pair scattering into the deformation-driving upsilon h(9/2)/f(7/2) ([541]1/2) orbital. (C) 1998 Published by Elsevier Science B.V. All rights reserved.