  In order to study the bound-state structure of the Helium halo nuclei, the
8-nucleon Yakubovsky formalism has been implemented for 8He in a 5-body
sub-cluster model, i.e. alpha+n+n+n+n. In this case, the 8-nucleon Yakubovsky
equations has been obtained in the form of two coupled equations, based on the
two independent components. In addition, by removing the contribution
interactions of the 8 and 7s bound nucleons in the formalism, the obtained
equations explicitly reduce to the 6-nucleon Yakubovsky equations for 6He, in
the case of effective 3-body model, i.e. alpha+n+n. In view of the expectation
for the dominant structure of 8He, namely an inert alpha-core and four
loosely-bound neutrons, Jacobi configurations of the two components in momentum
space have been represented to provide technicalities which were considered
useful for a numerical performance, such as bound-state calculations and
momentum density distributions for halo-bound neutrons.
