The results issued from the unfolding procedure are, in general, dependant on some input parameters, in particular, the default spectrum and the response functions. So in order to quantify the effect of a perturbation of both cited parameters, we have performed an overall sensitivity analysis. The variations considered for the first parameter together with its main characteristics are summarized in Table 3 as follows, taking into account a maximum number of iterations set at 2000 (stopping criterion) for the GRAVEL code