Phase analysis of 4He-4He scattering at energies of 40–50 MeV

Abstract

A phase analysis of 4 He-4 He elastic scattering is performed for energies of 40-50 MeV.Let us consider measurements of differential elastic scattering cross sections and phase analysis for the 4 Не-4 Не system at different energies and present a brief review of the experimental data obtained in different works for energies up to 50 MeV.Measurements of the differential elastic scattering cross sections and phase analysis at energies of 0.6-3.0 MeV were performed in [1], where values of scattering cross sections and phases were tabulated. This allows one to recalculate the scattering phases. The energy interval 3.0-5.0 MeV was studied in [2], but values of scattering phases and cross sections were shown only in figures. Energies of 3.8-11.9 MeV were analyzed in [3], where the results of phase analysis were tabulated, but the differential cross sections were shown only in figures. Energies of 12.9-21.6 MeV were examined in [4], but values of the scattering cross sections and scattering phases were shown in figures.Very accurate measurements of the differential elastic scattering cross sections and phase analysis were performed in [5,6], where the experimental scattering cross sections and scattering phases were tabulated for energies of 12.3-22.9 MeV. For energies of 18.0-29.5 MeV, good data were obtained in [7], where values of the elastic scattering cross sections and results of phase analysis were tabulated in detail. In [8], the differential scattering cross sections were measured and the phase analysis was performed for energies of 23.1-38.4 MeV; however, only the differential scattering cross sections were tabulated.Experimental investigations of the elastic scattering sections for energies of 36.8-47.3 MeV were performed in [9], where the measured cross sections were tabulated. Theoretical study of some energy values from this interval was performed in [10], where the parameters of the optical potential were found and then phases of 4 He-4 He elastic scattering were calculated for the known optical potential. The quality of optical fitting in this energy interval leaves much to be desired, which is seen immediately from the figures presented in [10]. In addition, when the scattering phases were extracted from the optical potentials, only their real parts were calculated, whereas the imaginary parts of the scattering phases were considered small, of the order of 1-2°. This is not justified for energies of 40 MeV and higher.Energies of 38.5 and 49.9 MeV were examined and the measured differential cross sections were presented in [11,12], but the phase analysis of these data was not performed in those works.From the foregoing review it follows that the standard phase analysis of the experimental data, that is, of the differential elastic scattering cross sections for the 4 He-4 He system at energies from 38.5 to 49.9 MeV has not yet been performed. The quality of fitting of the optical potential parameters in this energy interval can be considered only as preliminary, which is not surprising, because all these ...