Abstract
The measurements of np-spin observables at 0 degrees have been performed for the first time on the Delta-Sigma experimental facility of LHE JINR up to P-n = 4.5GeV/c using the monochromatic neutron beam. They include detailed measurements of the Delta sigma(L)(np) spin differences and the study of the np --> pn elastic charge-exchange process.
In the sigma(L)(np) and -Delta sigma(L)(I = 0) energy dependencies over the energy region T-kin = 1.2-3.7 GeV the peculiarity at 1.8 GeV was observed. Such energy behavior was predicted by the QCD approach as a signal of the NN --> 6q phase transition.
For the exhaustive investigation of this effect it is necessary to measure the energy dependence of the complete set of np observables with both longitudinal (L) and transverse (T) polarizations of the neutron beam and proton target. This will allow Direct Reconstruction of all three NN forward Scattering Amplitudes (DRSA) to be performed, and the observed peculiarity to be checked around T-kin = 1.8 GeV and at the higher energies using the Argand diagrams method.