K. Hagino

We carry out realistic coupled-channel calculations for the ${}^{11}\mathrm{Be}{+}^{208}\mathrm{Pb}$ reaction in order to discuss the effects of breakup of the projectile nucleus on subbarrier fusion. We discretize in energy the particle continuum states, which are associated with the breakup process, and construct the coupling form factors to these states on a microscopic basis. The incoming boundary condition is employed in solving coupled-channel equations, which enables us to define the flux

Paring correlations in weakly bound nuclei on the edge of the neutron-drip line is studied by use of a three-body model. A density-dependent contact interaction is employed to calculate the ground state of halo nuclei $^{6}\mathrm{He}$ and $^{11}\mathrm{Li}$, as well as a skin nucleus $^{24}\mathrm{O}$. Dipole excitations in these nuclei are also studied within the same model. We point out that the dineutron-type correlation plays a dominant role in the halo nuclei $^{6}\mathrm{He}$ and $^{11}\m

We investigate the spatial structure of the two-neutron wave function in the Borromean nucleus (11)Li, using a three-body model of (9)Li + n + n, which includes many-body correlations stemming from the Pauli principle. The behavior of the neutron pair at different densities is simulated by calculating the two-neutron wave function at several distances between the core nucleus (9)Li and the center of mass of the two neutrons. With this representation, a strong concentration of the neutron pair on

We study in detail the barrier distributions extracted from large-angle quasielastic scattering of heavy ions at energies near the Coulomb barrier. Using a closed-form expression for scattering from a single barrier, we compare the quasielastic barrier distribution with the corresponding test function for fusion. We examine the isocentrifugal approximation in coupled-channels calculations of quasielastic scattering and find that for backward angles it works well, justifying the concept of a barr

The measured fusion barrier distributions for $^{40}C\mathrm{a}+^{192}O\mathrm{s}$, ${}^{194}$Pt show significant features due to projectile excitation, while none are seen for $^{16}O+^{144}S\mathrm{m}$. This conflict is reconciled using realistic coupled-channel calculations, which show that the higher excitation energy of the ${3}^{\ensuremath{-}}$ state in ${}^{16}$O produces an adiabatic potential renormalization, without affecting the structure in the barrier distribution. This result indi

Using the method of the local transmission matrix, we generalize the well-known WKB formula for barrier penetrability to multichannel systems. We compare the WKB penetrability with a solution of the coupled-channels equations, and show that the WKB formula works well at energies well below the lowest adiabatic barrier. We also discuss the eigenchannel approach to a multichannel tunneling, which may improve the performance of the WKB formula near and above the barrier.

A recent publication reports that heavy-ion fusion cross sections at extreme sub-barrier energies show a continuous change of their logarithmic slope with decreasing energy, resulting in a much steeper excitation function compared with theoretical predictions. We show that the energy dependence of this slope is partly due to the asymmetric shape of the Coulomb barrier; that is, its deviation from a harmonic shape. We also point out that the large low-energy slope is consistent with the surprisin

The role of higher order coupling of surface vibrations to the relative motion in heavy-ion fusion reactions at near-barrier energies is investigated. The coupled channels equations are solved to all orders and also in the linear and the quadratic coupling approximations. Taking ${}^{64}$Ni + ${}^{92,96}$Zr reactions as examples, it is shown that all order couplings lead to considerably improved agreement with the experimentally measured fusion cross sections and average angular momenta of the c

We study the spatial structure of four valence neutrons in the ground state of $^{8}\mathrm{He}$ and $^{18}\mathrm{C}$ nuclei using a core$+4n$ model. For this purpose, we employ a density-dependent contact interaction among the valence neutrons, and solve the five-body Hamiltonian in the Hartree-Fock-Bogoliubov (HFB) approximation. We show that two neutrons with the coupled spin of $S=0$ exhibit a strong dineutron correlation around the surface of these nuclei, whereas the correlation between t

Recent high precision experimental data for heavy-ion fusion reactions at sub-barrier energies systematically show that a surprisingly large surface diffuseness parameter for a Woods-Saxon potential is required in order to fit the data. We point out that experimental data for quasielastic scattering at backward angles also favor a similar large value of the surface diffuseness parameter. Consequently, a double folding approach with a short-range imaginary potential for the compound nucleus forma