Searches for a dineutron in the nd → p( nn) charge-exhcange process at enegry T n = 0.5∇⋅2.0 GeV

Our measurements of differential cross-sections of both np ‎→‎ pn elastic and nd ‎→‎ p(nn) quasielastic charge-exchange reactions under 0∘ over the energy range Tn = 0.5∇⋅2.0 GeVallowed to define the ration Rdp between them and it separates two Flip and Non-Flip parts of the free np ‎→‎ pn process using the Dean theorem. The main idea of this theorem calculations is based on the Pauli principle for two slow neutrons in the final state that allowed to express the quantitative difference between the elastic and quasielastic np-reactions. However they should also differ in their quality because the deuteron is converted to the nn-pair and the nd-interaction becomes non absolutely elastic. In the first view we can take into account the binding energy ɛ ≈ 2.3 MeV but this simple correction can not explain all features which are observed in the momentum spectrum of the secondaries protons. We need to suppose that two slow neutrons in the final state form the intermediate system which has own distribution of internal Fermi momentum and it cannot be described by the suitable Hulthen expression or using other approaches for deuteron. Also it cannot be explaned by the hypoteisis of quasi particle dineutron with mass about of 2 mn.

charge-exchange, qusielastic reaction, dineutron, binding energy, Fermi-momentum, Hulthen expression