Investigation of the near-threshold cluster resonance in ${}^{14}\mathrm{C}$

An experiment for $p{(}^{14}\mathrm{C}$,${}^{14}{\mathrm{C}}^{\ast }{\to }^{10}\mathrm{B}\mathrm{e}+\alpha )p$ inelastic excitation and decay was performed in inverse kinematics at a beam energy of 25.3 MeV/u. A series of ${}^{14}\mathrm{C}$ excited states, including a new one at 18.3(1) MeV, were observed which decay to various states of the final nucleus of ${}^{10}\mathrm{B}\mathrm{e}$. A specially designed telescope-system, installed around the zero degree, played an essential role in detecting the resonant states near the $\alpha$-separation threshold. A state at 14.1(1) MeV is clearly identified, being consistent with the predicted band-head of the molecular rotational band characterized by the $\pi$-bond linear-chain-configuration. Further clarification of the properties of this exotic state is suggested by using appropriate reaction tools.