Experimental investigation of a linear-chain structure in the nucleus 14C

TL;DR

This paper reports the first experimental evidence of a linear-chain cluster state in the radioactive nucleus 14C, supporting theoretical predictions of such configurations in neutron-rich isotopes.

Contribution

It provides the first experimental observation of linear-chain cluster states in 14C, confirming theoretical models and suggesting neutron excess stabilizes such structures.

Findings

Observation of alpha-cluster states in 14C

Levels match theoretical linear-chain predictions

Supports existence of stabilized linear-chain structures

Abstract

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 {\alpha}-cluster states in the radioactive 14C nucleus. Using the 10Be+{\alpha} 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.