Unexpected decrease in moment of inertia between N=98-100 in Gd-162,Gd-164

From prompt gamma - gamma - gamma coincidence studies with a Cf-252 source, the yrast levels were identified from 2(+) to 16(+) and 14(+) in neutron-rich Gd-162,Gd-164, respectively. Transition energies between the same spin states are higher and moments of inertia lower at every level in N = 100 Cd-164 than in N = 98 Gd-162. The same trend is seen in Dy-164,Dy-166. These observations are in contrast to the continuous decrease in the 2(+) energy to a minimum at neutron midshell (N = 104) in Er, Yb, and Hf nuclei. The lowest known 2(+) energy in this region now occurs for N = 96 Nd-156 and next for N = 98 Sm-160, which are well removed from midshell for both protons and neutrons.