The absolute scale of neutrino masses is very important for understanding the evolution and the structure formation of the Universe as well as for nuclear and particle physics beyond the present standard model.
Elastic scattering of 4He atoms when they approach the surface of 4He liquid, has been studied. The liquid surface is assumed to be uniform and the density profile is the same along and perpendicular to the surface. The incident 4He atom will interact with a large number of 4He atoms in the liquid near the surface of liquid 4He. Hence, the effective interaction of the incident particle will be due to many-body forces.