We give a unified description for the ground states of He-6 and He-8 i
n a model comprising an alpha cluster and single-neutron clusters arra
nged into different configurations. Stochastic methods for selecting t
he the terms of the trial function yield excellent numerical convergen
ce both for the energy and wave function. The He-6 and He-8 energies a
re reproduced by the same effective force very well.