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New experimental results on the ratio Rdp of the quasi-elastic charge-exchange yield at the outgoing proton angle $ \theta_{{p,{\rm Lab}}}^{}$ = 0° for the nd $ \rightarrow$ p(nn) reaction to the elastic np $ \rightarrow$ pn charge-exchange yield are presented. The measurements were carried out at the Nuclotron of the Veksler and Baldin Laboratory of High Energies of the JINR (Dubna) at the neutron beam kinetic energies of 0.55, 0.8, 1.0, 1.2, 1.4, 1.8 and 2.0GeV. The intense neutron beam with small momentum spread was produced by break-up of deuterons which were accelerated and extracted to the experimental hall. In both reactions mentioned above the outgoing protons with the momenta p p approximately equal to the neutron beam momentum p n, beam were detected in the directions close to the direction of incident neutrons, i.e. in the vicinity of the scattering angle $ \theta_{{p,{\rm Lab}}}^{}$ = 0° . Measured in the same data taking runs, the angular distributions of the charge-exchange reaction products were corrected for the well-known instrumental effects and averaged in the vicinity of the incident neutron beam direction. These corrected angular distributions for every of nd $ \rightarrow$ p(nn) and np $ \rightarrow$ pn charge-exchange processes were proportional to the differential cross-sections of the corresponding reactions. The data were accumulated by the Delta-Sigma set-up magnetic spectrometer with two sets of multiwire proportional chambers located upstream and downstream of the momentum analyzing magnet. Inelastic processes were considerably reduced by the additional detectors surrounding the hydrogen and deuterium targets. The time-of-flight system was applied to identify the detected particles. The new Rdp data are compared with the existing ones, which were obtained below 1GeV, and with the calculations which were made using the phenomenological NN amplitude sets.

The new Delta-Sigma experimental data on the ratio R dp allowed separating the Flip and Non-Flip parts of the np → pn charge exchange process at the zero angle by the Dean formula. The PSA solutions for the np → np elastic scattering are transformed to the np → pn charge exchange representation using unitary transition, and good agreement is obtain.

New accurate data of the neutron-proton spin-dependent total-cross-section difference ΔσL(np) at the neutron-beam kinetic energies 1.39, 1.69, 1.89, and 1.99 GeV are presented. In general, these data complete the measurements of energy dependence of ΔσL(np) over the Dubna Synchrophasotron energy region. Measurements were carried out at the Synchrophasotron of the Veksler and Baldin Laboratory of High Energies of the Joint Institute for Nuclear Research. The quasi-monochromatic neutron beam was produced by breakup of extracted polarized deuterons. The deuteron (and hence neutron) polarization direction was flipped every accelerator burst. The initial transverse (with respect to beam momentum) neutron polarization was changed to a longitudinal one and longitudinally polarized neutrons were transmitted through the large proton longitudinally polarized target. The target polarization direction was inverted after one to two days of measurements. Four different combinations of the beam and target parallel and antiparallel polarization directions, both oriented along the neutron-beam momentum, were used at each energy. A fast decrease in −ΔσL(np) with increasing energy above 1.1 GeV and a structure in the energy dependence around 1.8 GeV, first observed from our previous data, seem to be well revealed. The new results are also compared with model predictions and with phase-shift analysis fits. The ΔσL quantities for isosinglet state I = 0, deduced from the measured ΔσL(np) values and known ΔσL(pp) data, are also given. The results of the measurements of unpolarized total cross sections σ0tot(np) at 1.3, 1.4, and 1.5 GeV and σ0tot(nC) at 1.4 and 1.5 GeV are presented as well. These data were obtained using the same apparatus and high-intensity unpolarized deuteron beams extracted either from the Synchrophasotron or from the Nuclotron.

The problem of separation of elastic and inelastic parts of a proton spectrum ofnp-interaction at energies 1–2 GeV is successfully solved. The factor of suppression of the inelastic background equals five at energy Tn=2 GeV.

New accurate data on the neutron-proton spin-dependent total cross section difference Δσ L(np) at the neutron beam kinetic energies 1.4, 1.7, 1.9 and 2.0 GeV are presented. A number of physical and methodical results on investigation of an elasticnp→pn charge exchange process over a few GeV region are also presented. Measurements were carried out at the Synchrophasotron and Nuclotron of the Veksler and Baldin Laboratory of High Energies of the Joint Institute for Nuclear Research.

New accurate results of the neutron-proton spin-dependent total cross section difference $\Delta\sigma_{\mathrm L}(np)$ at the neutron beam kinetic energies 1.39, 1.69, 1.89 and 1.99 GeV are presented. Measurements were carried out in 2001 at the Synchrophasotron of the Veksler and Baldin Laboratory of High Energies of the Joint Institute for Nuclear Research. A quasi-monochromatic neutron beam was produced by break-up of extracted polarized deuterons. The deuteron (and hence neutron) polarization direction was flipped every accelerator burst. The vertical neutron polarization direction was rotated onto the neutron beam direction and longitudinally (L) polarized neutrons were transmitted through a large proton L-polarized target. The target polarization vector was inverted after 1-2 days of measurements. The data were recorded for four different combinations of the beam and target parallel and antiparallel polarization directions at each energy. A fast decrease of $\Delta\sigma_{\mathrm L}(np)$ with increasing energy above 1.1 GeV was confirmed. The structure in the $\Delta\sigma_{\mathrm L}(np)$ energy dependence around 1.8 GeV, first observed from our previous data, seems to be well pronounced. The new results are also compared with model predictions and with phase shift analysis fits. The $\Delta\sigma_{\mathrm L}$ quantities for isosinglet state I = 0, deduced from the measured $\Delta\sigma_{\mathrm L}(np)$ values and the known $\Delta\sigma_{\mathrm L}(pp)$ data, are also given. The results were completed by the measurements of unpolarized total cross sections $\sigma_{0\mathrm{tot}}(np)$ at 1.3, 1.4 and 1.5 GeV and $\sigma_{0\mathrm{tot}}(n$ C) at 1.4 and 1.5 GeV. These data were obtained using the same apparatus and high intensity unpolarized deuteron beams were extracted either from the Synchrophasotron, or from the Nuclotron.

Preliminary results of the ΔσL(np) at 1.4, 1.7, 1.9 and 2.0 GeV are presented. They were obtained during the two data-taking runs at the JINR Dubna Synchrophasotron in 2001 and complete the existing data above 1.1 GeV. The data analysis is in progress. The aim of the present studies is to determine the imaginary and real parts of the np spin-dependent forward scattering amplitudes over this energy range.

New data on the spin-dependent np observables measured with quasi-monochromatic polarized neutron beam in the energy region from 1.2 to 3.7 GeV are presented. Further measurements of np scattering observables using the JINR LHE polarization facility (longitudinal and transverse polarized neutron beams and a polarized proton target) are discussed. The aim of these studies is to determine the imaginary and real parts of the forward scattering amplitudes for np and for isospin I=0 systems above 1.1 GeV.

The measurements of np-spin observables at 0° have been performed for the first time on the Delta-Sigma experimental facility of LHE JINR up to P n = 4.5 GeV/c using the monochromatic neutron beam. They include detailed measurements of the Δσ L(np) spin differences and the study of the np → pn elastic charge-exchange process. In the Δσ L(np) and −Δσ L(I = 0) energy dependencies over the energy region Tkin = 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 Tkin = 1.8 GeV and at the higher energies using the Argand diagrams method.

The first results of the measurement of 0o of the cross-section ratioR dp=0.50±0.02 in charge-exchange (np) reaction on H2/D2 targets at the neutron beam kinetic energie 1.0 GeV are presented. As a result the value of the ratio of non spin-flip to spin-flip contribution innp→pn charge-exchange at 0o r =0.33±0.03 was obtained.