Data on the Neutron-Neutron Scattering Length from the nd-Breakup Reaction at E.sub.n = 8 MeV and E.sub.n = 11 MeV

A kinematically complete experiment devoted to studying the [Formula omitted]-breakup reaction at energies of 8 and 11 MeV via detecting all three secondary particles was performed. The [Formula omitted] neutron-neutron ( [Formula omitted]) scattering-length values of [Formula omitted] and [Formula omitted] fm at, respectively, [Formula omitted] and [Formula omitted] MeV were obtained from a comparison of the experimental dependence of the yield of the [Formula omitted]-breakup reaction on the relative energy of the [Formula omitted] pair with the results of a simulation. An analysis of the values obtained for the [Formula omitted] scattering length, together with data from other experiments, confirms the hypothesis that three-nucleon forces affect the parameters of [Formula omitted] interaction that are extracted from reactions involving few-nucleon systems and gives a new asymptotic [Formula omitted] scattering length, [Formula omitted] fm.