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International audience; Differential cross sections of p–6He elastic scattering were measured in inverse kinematics at an incident energy of 200 A MeV, covering the high momentum transfer region of 1.7–2.7 fm−1. The sensitivity of the elastic scattering at low and high momentum transfers to the density distribution was investigated quantitatively using relativistic impulse approximation calculations. In the high momentum transfer region, where the present data were taken, the differential cross section has an order of magnitude higher sensitivity to the inner part of the 6He density relative to the peripheral part (15:1). This feature makes the obtained data valuable for the deduction of the inner part of the 6He density. The data were compared to a set of calculations assuming different proton and neutron density profiles of 6He. The data are well reproduced by the calculation assuming almost the same profiles of proton and neutron densities around the center of 6He, and a proton profile reproducing the known point-proton radius of 1.94 fm. This finding is consistent with the assumption that the 6He nucleus consists of a rigid α-like core with a two-neutron halo.

Tow parameters of a WoodsγSaxon form assumed for the neutron distribution of 208 Pb nucleus are determined with the reaction cross-section and the dip position of the differential cross-section. These observables are calculated based on the relativistic impulse approximation. For the proton density we take the profile obtained from the electron scattering by unfolding the proton form factor.

Using the concept of the neutron Bloch wave presented previously, the possibility of an effective nuclear reaction of a thermal neutron and a nucleus in a boundary region of crystals is determined. Many experimental data of nuclear transmutations in the surface layer or surface region of solid materials loaded with deuterium supposedly induced by nuclear reactions with a thermal neutron are investigated using the nature of the neutron Bloch wave in solids. The physics of the nuclear reaction phenomena is discussed in the trapped neutron catalyzed fusion model.

More than 25 typical experimental data sets of the cold fusion phenomenon have been analyzed phenomenologically by the TNCF (trapped neutron catalyzed fusion) model based on an assumption of the quasi-stable existence of the thermal neutrons in solids with special characteristics, giving a consistent explanation of the whole data set. The densities of the assumed thermal neutron in solids have been determined in the analyses from various experimental data and were in a range of 103 to 1012 cm-3. The success of the analyses verifies the validity of the assumption of the trapped thermal neutron. Physical bases of the model were speculated, facilitating the quasi-stable existence of the thermal neutron in the crystals, thereby satisfying definite conditions.

Neutron elastic-scattering observables are calculated on the basis of the relativistic impulse approximation which has succeeded in analysis of proton-nucleus elastic scattering, particularly at intermediate energies. Calculations are performed for some spin-zero target nuclei: 16O, 40Ca, 90Zr and 208Pb. A difference between predictions for the spin-observables of the proton and neutron is obtained in the case of a heavy target at low energy. The Coulomb potential is found to mainly affect these observables by comparing results of the neutron with those of the proton.

Observables of proton elastic scattering from nickel isotopes (48–82 Ni ) are calculated based on relativistic impulse approximation (RIA), and nuclear density distributions are provided by relativistic mean-field (RMF) calculations. Contributions of a medium effect and multiple scattering to observables are evaluated and shown to be small at incident proton energies from 200 MeV through 500 MeV so that it is confirmed to perform a model analysis based on the fundamental RIA calculation. For 58,60,62,64 Ni isotopes, are considered proton distributions which are obtained by means of unfolding the charge form factor of proton from charge densities determined by the experiments of electron scattering. Through comparisons between results for the different proton densities, contributions of proton form factor to proton distributions and to elastic scattering observables at 300 MeV are discussed. It is shown that the neutron distribution is determined from the restricted observables, reaction cross-section and the first dip of differential cross-section, based on a model analysis of Woods–Saxon distribution in the case of 64 Ni target at 300 MeV. Contributions of tensor density and empirical proton density are shown to obtaining the neutron distribution with the model analysis. Compared with the similar studies for 40,60 Ca and 208 Pb , problems of the model analysis, which arise out of errors in observables, are discussed.

We study theoretically how we can determine the neutron density distributions of unstable nuclei from proton elastic scattering. We apply the relativistic impulse model to study the sensitivities of the observables to the density distributionswhich are expressed in Woods-Saxon form. We find that the both radius and diffuseness of densities can be determined from restricted elastic scattering data in principle. We think this result is helpful to design future experiments., Comment: 22 pages, 9 ps figures, Latex