A. S. B. Tariq

Microscopic 6Li-28Si potential from the energy-density functional theory

The experimental differential cross-sections for the 6Li elastic scattering by 28Si over the incident energies ELi=7.5–99.0 MeV and vector analyzing power data at 22.8 MeV have been analyzed in terms of a non-monotonic potential, microscopically derived from the energy-density functional (EDF) theory using a realistic two-nucleon potential that incorporates effects of the Pauli principle. The data are accounted for well without any need for renormalization of the potential or adjustment of its parameters. Inclusion of a static spin-orbit potential with the EDF-generated central real one is found to describe satisfactorily the features of the vector analyzing power data.

Non-monotonic potentials and vector analyzing powers of 6,7Li scattering by 12C, 26Mg, 58Ni, and 120Sn

The data on the elastic scattering cross-section (CS) and vector analyzing power (VAP) of 6,7Li incident on 12C , 26Mg, 58Ni and 120Sn nuclei are analyzed in terms of an optical model (OM) potential, the real part of which is generated from a realistic two-nucleon interaction using the energy-density functional (EDF) formalism. The EDF-generated real part of the potential is non-monotonic (NM) in nature. This NM real potential part, without any renormalization, along with an empirically determined imaginary part and spin-orbit potential, embodying the underlying physics of projectile excitation, can successfully account for both CS and VAP data in all four cases. This investigation, for the first time, using the simple OM analysis accounts well for the opposite signs of the VAP data of elastically scattered 6,7Li by 58Ni at Elab≈20 MeV and by 120Sn at Elab=44 MeV. The ramification of successfully describing the data by the EDF-generated potential to the equation of state of nuclear matter is discussed.

Molecular versus squared Woods–Saxon α-nucleus potentials in the 27Al(α, t)28Si reaction

The differential cross-section of the 27Al(α, t)28Si reaction for 64.5 MeV incident energy has been reanalysed in DWBA with full finite range using a squared Woods–Saxon (Michel) α-nucleus potential with the modified value of the depth parameter α = 2.0 as reported in a comment article by Michel and Reidemeister. This new value produces significant improvement in fitting the data of the reaction with its overall performance, in some cases, close to that previously observed for the molecular potential. Although the non-monotonic shallow molecular potential with a soft repulsive core and the Michel potentials produce the same quality fits to the elastic scattering and non-elastic processes, they are not phase equivalent. The two types of potential produce altogether different cross-sections, particularly at large reaction angles. The importance of the experimental cross-sections at large angles for both elastic scattering and non-elastic processes is elucidated.

Non-monotonic potential description of alpha–Zr refractive elastic scattering

Experimental differential cross sections of α elastic scattering by 90Zr in the 15.0–141.7 MeV range of the bombarding energies have been analysed within the framework of an optical model using non-monotonic (NM) potentials. These potentials are generated from the energy-density functional theory using a realistic two-nucleon potential coupled with an appropriate consideration of the Pauli principle. The NM nature of the real part of the potential seems to be gradually diminishing at energies beyond 118.0 MeV. The Airy structure of the nuclear rainbow scattering data in the energy range of 79.5–141.7 MeV is for the first time well accounted for by the shallow NM potential. Two potential families, which are located in the real part, bear a linear variation of a volume integral in the energy range 25.0–141.7 MeV with a threshold anomaly at the lower energies. The potential contains an interior repulsive part that, with energy, shifts towards the surface and gradually weakens until it is almost lost in the nuclear surface. The requirement of a deep attractive real part of the nuclear potential seems to be generally non-stringent for describing the nuclear rainbow oscillations. Some discrete ambiguities in the potentials seem to persist even when the ‘exponential falloff’ in the angular distribution following the ‘rainbow angle’ is well reproduced in this investigation using the NM real part of the optical potentials.

Normalization constant of the (α, t) reaction

SummaryThe DWBA analyses are performed for the ground states and other strong transitions populated in the (α, t) reaction on various targets ranging fromA = 16 to 208 with zero-range and with finite-range corrections in the local energy approximation (LEA). The normalization constants without and with the LEA are found to be, respectively,D20 = (18.16±3.49) × 10 MeV fm andD = (8.67±1.60)× 10 MeV2 fm3 which are reasonably consistent with some other previous studies. The normalization constants for the (α, t) reaction on the Al target are also deduced for different incident energiesEα = 25.0, 25.2, 64.5, 80.0 and 104.0 MeV for studying any possible energy dependence of the normalization constant. No tangible energy dependence was found in the present study and hence the LEA seems to be valid reliably within the energy range studied. The ratioD20/D bears a value of about 2.0 which is remarkably constant over the target masses and incident energies.