  The long range potential of helium-helium interaction, which requires
accurate 'ab initio' calculation, due to the small value of the potential
depth, approximately 11 K (0.091 kJ/mol) at 2.96 angstrom, will be obtained in
this study by an alternative technique. This work presents a robust and
consistent procedure that provides the long range potential directly from
experimental data. However, it is difficult to obtain experimental data
containing information regarding such a small potential depth. Thereby,
sensitivity analysis will be used to circumvent this difficulty, from which
viscosity data at lower temperatures (<5K) were chosen as appropriate data to
be used to retrieve the potential function between 3 and 4 angstrom. The linear
relationship between the potential energy function and the viscosity
coefficient will be established under quantum assumptions and the Bose-Einstein
statistic. The use of quantum theory is essential, since the temperatures are
below 5K. The potential obtained in this study describes the viscosity with an
average error of 1.68% that is less than the experimental error (5%), with the
results being similar to those obtained for recent 'ab initio' potentials.
