Development of a SQUID-type detector and a study on systematics of neutron optical potential in the energy region from 0 to a few MeV.

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The optical model is the most valid and useful model for neutron cross-section evaluation in the nuclear engineering field. The model describes an averaged interacton between neutrons and nuclei in the wide neutron energy range by using the complex optical potential, U(r, E) = V(r, E) + iW(r, E). Continuing efforts have been devoted to a more precise determination of the neutron optical potential.On the other hand, recent studies have shown that an optical potential derived from the dispersion theory represents both the neutron scattering states and bound states in the wide neutron energy range. The dispersion relation offers a useful method to evaluate optical potential more precisely. Usually W(r, E) must be known in the wide energy range for the analysis based on the relation. So far, however, the imaginary surface potential W(r, E) less than the Fermi-surface energy has not been well investigated because the value is not obtained from experiments directly.From this point of view, in the present work, we have studied the systematics of neutron optical potential. We carried out (d, P) or (p, d) reaction experiments for several nuclei by using polarized beam at RCNP (Osaka University) and evaluated the spreading width, G, of the single particle or hole states. The corresponding W(r, E) was calculated on the basis of the relation G = 2W.Previously obtained data were reanalyzed in the same manner. In addition to this, we made some basic investigation on a new type SSD telescope system for the future experiments related to this subject.From the work in this project, we have established an evaluation method of imaginary surface potential W(r, E) of the neutron optical potential and found the feasibility for further investigations.