Neutron-dominant quadrupole collective motion in 16C

Inelastic proton scattering to the 2(1)(+) state of neutron-rich C-16 is studied in inverse kinematics using a 33-MeV/nucleon beam. The deformation parameter beta(')(pp)=0.47(5) obtained is consistent with the global systematics of even-even nuclei, based on the homogeneous quantum liquid-drop model. This result contrasts that of a recent lifetime measurement for the 2(1)(+) state in C-16, where an anomalously reduced E2 transition strength is observed. A combination of these two results yields a large M-n/M-p ratio of about 7, indicating a dominant neutron contribution to the quadrupole collectivity.