New candidate for an alpha cluster condensed state in O 16 ( α , α ′ ) at 400 MeV

• Published in: Physics letters. B 2007-09, Vol.653 (2), p.173-177
• Main Authors: Wakasa, T., Ihara, E., Fujita, K., Funaki, Y., Hatanaka, K., Horiuchi, H., Itoh, M., Kamiya, J., Röpke, G., Sakaguchi, H., Sakamoto, N., Sakemi, Y., Schuck, P., Shimizu, Y., Takashina, M., Terashima, S., Tohsaki, A., Uchida, M., Yoshida, H.P., Yosoi, M.
• Format: Article
• Language: English
• Subjects: [formula omitted] scattering; α cluster condensation
• ISSN: 0370-2693; 1873-2445
• DOI: 10.1016/j.physletb.2007.08.016

Inelastic α scattering on 16O is studied at 400 MeV using an ice target. Near the 4 α breakup threshold of 14.4 MeV, a broad peak is observed at an excitation energy of 13.6 ± 0.1  MeV with a width of 0.6 ± 0.2  MeV . The spin-parity is estimated to be 0 + from the momentum-transfer dependence. The observed width is significantly larger than that of the 0 + state at 12.0 MeV with the α + C 12 structure, indicating a well-developed α cluster structure. The magnitude of the cross section is sensitive to the density distribution of the constituent α clusters. The observed cross section is consistent with the theoretical prediction for the α cluster condensed state, characterized by its dilute density distribution with a large root-mean-square radius.