Experimental investigation of a linear-chain structure in the nucleus 14 C
H. Yamaguchi (Center for Nuclear Study (CNS), University of Tokyo, RIKEN campus, 2-1 Hirosawa, Saitama, Wako, 351-0198, Japan); D. Kahl (Center for Nuclear Study (CNS), University of Tokyo, RIKEN campus, 2-1 Hirosawa, Saitama, Wako, 351-0198, Japan, School of Physics and Astronomy, the University of Edinburgh, Peter Guthrie Tait Road, Edinburgh, EH9 3BF, UK); S. Hayakawa (Center for Nuclear Study (CNS), University of Tokyo, RIKEN campus, 2-1 Hirosawa, Saitama, Wako, 351-0198, Japan); Y. Sakaguchi (Center for Nuclear Study (CNS), University of Tokyo, RIKEN campus, 2-1 Hirosawa, Saitama, Wako, 351-0198, Japan); K. Abe (Center for Nuclear Study (CNS), University of Tokyo, RIKEN campus, 2-1 Hirosawa, Saitama, Wako, 351-0198, Japan); et al - Show all 26 authors
It is a well-known fact that a cluster of nucleons can be formed in the interior of an atomic nucleus, and such clusters may occupy molecular-like orbitals, showing characteristics similar to normal molecules consisting of atoms. Chemical molecules having a linear alignment are commonly seen in nature, such as carbon dioxide. A similar linear alignment of the nuclear clusters, referred to as linear-chain cluster state (LCCS), has been studied since the 1950s, however, up to now there is no clear experimental evidence demonstrating the existence of such a state. Recently, it was proposed that an excess of neutrons may offer just such a stabilizing mechanism, revitalizing interest in the nuclear LCCS, specifically with predictions for their emergence in neutron-rich carbon isotopes. Here we present the experimental observation of α -cluster states in the radioactive 14 C nucleus. Using the Be10+α resonant scattering method with a radioactive beam, we observed a series of levels which completely agree with theoretically predicted levels having an explicit linear-chain cluster configuration. We regard this as the first strong indication of the linear-chain clustered nucleus.
