Characteristic \alpha and ^{6}He decays of the linear-chains in ^{16}C

The linear-chain states of ${}^{16}$C and their decay modes are theoretically investigated by using the antisymmetrized molecular dynamics. It is found that the positive-parity linear-chain states have the $(3\mathrm{/}{2}_{\pi }^{-}{)}^2(1\mathrm{/}{2}_{\sigma }^{-}{)}^2$ configuration and primary decay to the ${}^{12}$Be($2_1^{+}$) as well as to the ${}^{12}$Be(g.s.) by the $\alpha$ particle emission. Moreover, we show that they also decay to the $^6{\rm He}+{}^{10}{\rm Be}$ channel. In the negative-parity states, it is found that two types of the linear-chains exist. One has the valence neutrons occupying the molecular-orbits $(3\mathrm{/}{2}_{\pi }^{-}{)}^2(1\mathrm{/}{2}_{\sigma }^{-})(3\mathrm{/}{2}_{\pi }^{+})$, while the other’s configuration cannot be explained in terms of the molecular orbits because of the strong parity mixing. Both configurations constitute the rotational bands with large moment of inertia and intra-bands $E2$ transitions. Their $\alpha$ and ${}^6\mathrm{H}\mathrm{e}$ reduced widths are sufficiently large to be distinguished from other non-cluster states although they are smaller than those of the positive-parity linear-chain.