Manabu Ueda

Elastic scattering of a halo nucleus at medium energies

Abstract The angular distribution of elastic scattering of a halo nucleus is compared to that between stable nuclei. We show that the optical limit approximation of the Glauber theory, which is conventionally used to describe collisions of stable nuclei, overestimates the reaction cross section when the projectile has an extended neutron halo. This suggests the important role played by the breakup reactions in the elastic scattering of halo nuclei, and also that the corresponding dynamic polarization potential has a sizable positive real part. The overestimate is shown to occur for a wide range of the incident energy, though it decreases with increasing bombarding energy.

Suppressed fusion cross section for neutron halo nuclei

Abstract Fusion reactions of neutron-halo nuclei are investigated theoretically with a three-body model. The time-dependent wave-packet method is used to solve the three-body Schrodinger equation. The halo neutron behaves as a spectator during the Coulomb dissociation process of the projectile. The fusion cross sections of 11Be–209Bi and 6He–238U are calculated and are compared with measurements. Our calculation indicates that the fusion cross section is slightly hindered by the presence of weakly bound neutrons.

Time-dependent wave-packet approach for fusion reactions of halo nuclei

Abstract The fusion reaction of a halo nucleus 11 Be on 208 Pb is described by a three-body direct reaction model. A time-dependent wave packet approach is applied to a three-body reaction problem. The wave packet approach enables us to obtain scattering solutions without considering the three-body scattering boundary conditions. The time evolution of the wave packet also helps us to obtain intuitive understanding of the reaction dynamics. The calculations indicate a decrease of the fusion probability by the presence of the halo neutron.

Application of an absorbing boundary condition to nuclear breakup reactions

Absorbing boundary condition approach to nuclear breakup reactions is investigated. A key ingredient of the method is an absorbing potential outside the physical area, which simulates the outgoing boundary condition for scattered waves. After discretizing the radial variables, the problem results in a linear algebraic equation with a sparse coefficient matrix, to which efficient iterative methods can be applicable. No virtual state such as discretized continuum channel needs to be introduced in the method. Basic aspects of the method are discussed by considering a nuclear two-body scattering problem described with an optical potential. We then apply the method to the breakup reactions of deuterons described in a three-body direct reaction model. Results employing the absorbing boundary condition are found to accurately coincide with those of the existing method which utilizes discretized continuum channels.

Fusion Reaction of Halo Nuclei : Proton Halo versus Neutron Halo

The fusion reaction of halo nuclei on heavy target is investigated in a three-body reaction model. A time-dependent wave-packet method is employed to solve the three-body Schrodinger equation. We find that the fusion probability is enhanced by the presence of the halo nucleon for proton halo nuclei, contrary to the neutron halo case for which we previously reported that the halo neutron suppresses the fusion. The reason of the opposite effect between proton and neutron halos is discussed.

Forward nuclear glory scattering of a halo nucleus

Abstract We show that characteristics of the elastic scattering of a halo nucleus manifest themselves in the forward nuclear glory scattering. Using the analysis of the sum of difference cross section, we demonstrate that the nuclear scattering amplitude at extremely forward angles is strongly enhanced compared with that in the scattering of stable nuclei if the projectile in heavy-ion collisions is a halo nucleus. Another characteristic is that the first glory minimum shifts towards a smaller angle. This can be seen if one can choose a scattering system, where the Coulomb rainbow angle is larger than the first glory minimum.

Fusion reaction of halo nuclei : A real-time wave-packet method for three-body tunneling dynamics

Fusion reactions of halo nuclei are investigated theoretically with a three-body model. The time-dependent wave-packet method is used to solve the three-body Schrodinger equation. Dynamics of the halo nucleons are visualized in the coordinate space. Significant differences between the neutron-halo and the proton-halo systems are discussed in connection to the Coulomb breakup process. The fusion cross sections are calculated for 11Be - 209Bi and 6He - 238U. Our calculation indicates that the fusion cross section is slightly hindered by the presence of weakly bound neutrons. The present results nicely agree with recent measurements.

Absorbing Boundary Condition Approach for Breakup Reactions of Halo Nuclei

Application of the absorbing boundary condition is discussed to analyse breakup reactions of weakly bound nuclei. The key ingredient is an introduction of the absorbing potential outside the physical area which simulates the outgoing boundary condition approximately. The scattering problem is then recasted into the Schrodinger like equation with a source term in the interaction region and with the vanishing boundary condition at the boundary. We demonstrate usefulness of the method taking a few examples. Deuteron breakup reactions are examined comparing present results with those by the continuum-discretized coupled-channel method. We next discuss the breakup reactions of single-neutron halo nucleus, 1 1 Be.

Fusion reaction of halo nuclei: A real‐time wave‐packet method for three‐body tunneling dynamics

We investigate fusion cross section of a nucleus with a valence neutron, using the time‐dependent wave‐packet method. For a stable projectile, in which the valence neutron is tightly bound (en −1 MeV), the fusion probability is hindered by the presence of the weakly bound neutron.

Continuum Response and Reaction in Neutron‐Rich Be Nuclei

We study E1 resonances, breakup and fusion reactions for weakly bound Be nuclei. The absorbing‐boundary condition (ABC) is used to describe both the outgoing and incoming boundary conditions. The neutron continuum plays important roles in response and reaction of neutron drip‐line nuclei.