Surface localization of the dineutron in ${}^{11}$Li

Abstract

The formation of a dineutron in the nucleus ${}^{11}$Li is found to be localized to the surface region. The experiment measured the intrinsic momentum of the struck neutron in ${}^{11}$Li via the $(p,pn)$ knockout reaction at 246 MeV/nucleon. The correlation angle between the two neutrons is, for the first time, measured as a function of the intrinsic neutron momentum. A comparison with reaction calculations reveals the localization of the dineutron at $r\sim 3.6$ fm. The results also support the density dependence of dineutron formation as deduced from Hartree-Fock-Bogoliubov calculations for nuclear matter.

19 pages, 4 figures. Accepted for Physical Review Letters