Data on the Neutron–Neutron Scattering Length from the nd-Breakup Reaction at En = 8 MeV and En = 11 MeV

Abstract

A kinematically complete experiment devoted to studying the nd-breakup reaction at energies of 8 and 11 MeV via detecting all three secondary particles was performed. The {}^{1}S_{0} neutron–neutron (nn) scattering-length values of a_{nn}={-}19.8pm 0.4 and {-}19.0pm 0.5 fm at, respectively, E_{n}=8 and 11 MeV were obtained from a comparison of the experimental dependence of the yield of the nd-breakup reaction on the relative energy of the nn pair with the results of a simulation. An analysis of the values obtained for the nn scattering length, together with data from other experiments, confirms the hypothesis that three-nucleon forces affect the parameters of nn interaction that are extracted from reactions involving few-nucleon systems and gives a new asymptotic nn scattering length, a_{nn}={-}16.1pm 0.1 fm.