Reorientation-effect measurement of the first 2 state in C: confirmation of oblate deformation
M. Kumar Raju · J. N. Orce · P. Navratil · G. C. Ball · T. E. Drake · S. Triambak · G. Hackman · C. J. Pearson · the TIGRESS/UWC Collaboration
A Coulomb-excitation reorientation-effect measurement using the TIGRESS ray spectrometer at the TRIUMF/ISAC II facility has permitted the first determination of the diagonal matrix element in C from particle coincidence data. Required state-of-the-art no-core shell model calculations of the nuclear polarizability for the ground and first-excited (2) states in C using chiral NN NLO500 and NN+3NF350 interactions have been performed. Consistent predictions show a larger polarizability than previously anticipated. The polarizability of the 2 state is introduced into the current and previous Coulomb-excitation reorientation-effect analysis of C. Spectroscopic quadrupole moments of eb and eb are determined, respectively, yielding a weighted average of eb, in agreement with recent ab initio calculations. The present measurement confirms that the 2 state of C is oblate and emphasizes the important role played by the nuclear polarizability in Coulomb-excitation studies of light nuclei.