Inelastic proton scattering to the $2_1^{+}$ state of neutron-rich ${}^{16}\mathrm{C}$ is studied in inverse kinematics using a 33-MeV/nucleon beam. The deformation parameter ${\beta }_{{\mathit{pp}}^{\text{'}}}=0.47(5)$ 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 ${}^{16}\mathrm{C}$, 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.

• Received 1 December 2004

DOI:https://doi.org/10.1103/PhysRevC.73.024610