Polarization Observables in Few-Nucleon Scattering

Systems composed of a few nucleons are subject of experimental studies for many years with the aim to gain precise information on the interaction between nucleons. Intermediate energies, below the threshold for pion production, deserve special attention: it is a region where comparison with exact theoretical calculations is possible, while the sensitivity to various aspects of interaction, like subtle effects of the dynamics beyond the pairwise nucleon-nucleon force, is significant. In addition to differential cross section, the observables related to nuclear polarization are studied, like vector and tensor analyzing powers, spin-correlation coefficients or polarization transfer coefficients. A brief survey of results of recent studies in few-nucleon systems is given.

POLARIZATION TRANSFER MEASUREMENT FOR d-p ELASTIC SCATTERING: TO SEARCH FOR THREE NUCLEON FORCE EFFECTS

Precise measurements of the deuteron to proton polarization transfer coefficients for the d-p elastic scattering have been made at 135 MeV/u at RIKEN Accelerator Research Facility. The obtained results are compared with the Faddeev calculations based on modern nucleon-nucleon forces together with Tucson-Melbourne Tucson-Melbourne' and Urbana–Argonne type of three nucleon forces.

THREE-BODY EFFECTS IN $\vec{p}d$ ELASTIC SCATTERING AT 250 MEV

The angular distributions of the cross section, the proton analyzing power and all of proton polarization transfer coefficients of [Formula: see text] elastic scattering were measured at 250 MeV. The present data are compared with theoretical predictions based on exact solutions of the three-nucleon Faddeev equations and modern realistic nucleon-nucleon potentials combined with three-nucleon forces. These results call for a better understanding of the spin structure of the three-nucleon force and very likely for a full relativistic treatment of the three-nucleon continuum.