Neutron halo, tritons and alpha clusters in the nucleus ${^8}He$

Abstract

Recent experiments clearly demonstrate the importance of the excited state $2^+$ at 1.8 MeV in the substruture ${^6}He$ for the ground state of the nucleus ${^8}He$. It is shown here that this means that the ground state structure of ${^8}He$ rather than being $\alpha$ + 4n is actually ${^3}H$ + ${^3}H$ +2n. As such the pair of tritons would form a compact core around which the two valence neutrons provide a halo structure in ${^8}He$. Hence both ${^6}He$ and ${^8}He$ are two neutron halo nuclei but with cores of quite different nature. All this demonstrates significance of triton clustering in neutron rich nuclei.