  Background: Several Time-Dependent Hartree-Fock-Bogoliubov (TDHFB)
calculations predict that the super- fluidity enhances the fluctuations of the
fusion barrier. This effect is not fully understood and not yet revealed
experimentally. Purpose: The goal of this study is to investigate empirically
the effect of the superfluidity on the fusion barrier width. Method: First, the
local regression method is introduce and used to determine the barrier
distribution more precisely. A second method that requires only the calculation
of an integral of the cross section is developed to determine accurately the
fluctuations of the barrier. A benchmark is done between this two methods and
with the fitting method usually used. This integral method showing a better
agreement in a test case, it is applied systematically in a selection of 115
fusion reactions. Results: The fluctuations of the barrier for superfluid
systems are on average larger than for magic or semi-magic nuclei. This is due
to the deformation effects and the effect of the superfluidity. To disentangle
those two effects, we compare the experimental width to the width estimated
from a model that takes into account the tunneling, the deformation and the
vibration effect. The deviation of the experimental width from this theory for
reaction between superfluid nuclei shows that the superfluidity enhance the
fusion barrier width. Conclusions: This analysis shows that the predicted
effect of the superfluidity on the width of the barrier is real and is of the
order of 1 MeV.
