Bound state properties of Borromean halo nuclei: 6He and 11Li

Cluster emission, transfer and capture in nuclear reactions

Resonance phenomena in quantum physics are very familiar in many fields of physics, but we have not yet obtained a complete physical understanding, mathematical description or computational treatment, especially in the case of many-body resonances. Recently, in experimental developments concerning unstable nuclear physics and heavy-ion nuclear reactions, much interest has been concentrated on many-body resonance problems. In the last quarter century, theoretical and mathematical treatments of many-body resonances have experienced great development through application of the complex scaling method (CSM). We can now treat resonant states of three-body systems in the same way as those of twobody systems. In this article, starting from the definition of a resonant state and discussion of its norm, we present a summary of recent studies of CSM to treat many-body resonances and applications to three-body resonant states in two-neutron halo nuclei and three-cluster systems.

The Complex Scaling Method for Many-Body Resonances and Its Applications to Three-Body Resonances

This paper is focused mainly on the subject of elastic magnetic electron scattering and how it has come to be a useful tool for studying the spatial distributions of convection and magnetization currents in the nuclear ground state. Using such a probe, emphasis is clearly placed on the electromagnetic currents provided by the valence nucleons in the nucleus, indeed, by neutrons as well as protons. These do not yield a complete description of the problem, however, and more complex nuclear many-body configurations are generally required. Various models are employed (shell-model configuration mixing, core-polarization effects, models of deformed nuclei, for instance), giving rise to quantitative comparisons with experimental measurements. Moreover, to achieve such successful descriptions, especially at high momentum transfers, it is frequently necessary to go beyond a purely one-body nucleonic reaction mechanism and to include the effects of two-body meson-exchange currents based on non-nucleonic degrees of freedom ($\ensuremath{\pi}$,$\ensuremath{\rho}$,$\ensuremath{\Delta},\dots{}$). The authors discuss all of these various facets of the problem, beginning with surveys of the historical development of the field and of the experimental techniques employed in such studies. They present a detailed treatment of the formalism needed in discussions of elastic electron scattering, including an introduction to the density-matrix approach to the nuclear many-body problem, with simple examples to clarify the ideas involved. For the nonspecialist a separate section of illustrative examples is supplied in which qualitative discussions of various aspects of the physics accessible in such ($e$,${e}^{\ensuremath{'}}$) studies are highlighted. Experimental and theoretical results for a large number of nuclei ranging from $A=2 \mathrm{to} 209$ are described in detail; this represents a compilation of virtually all of the high-quality data that are available at present. The paper concludes with projections as to which directions may be followed in the future, in particular, with a relatively complete discussion of the use of polarization in elastic electron scattering.

Elastic magnetic electron scattering from nuclei

The $\alpha$-bosonic properties such as single-$\alpha$ orbits and occupation numbers in $J^\pi$=$0^+$, $2^+$, $1^-$ and $3^-$ states of $^{12}$C around the $3\alpha$ threshold are investigated with the semi-microscopic $3\alpha$ cluster model. As in other studies, we found that the $0^+_2$ ($2^+_2$) state has dilute-$3\alpha$-condensate-like structure in which the $\alpha$ particle is occupied in the single $S$ ($D$) orbit with about 70% (80%) probability. The radial behaviors of the single-$\alpha$ orbits as well as the occupation numbers are discussed in detail in comparison with those for the $0^+_1$ and $2^+_1$ states together with the $1^-_1$ and $3^-_1$ states.

Single $\alpha$-particle orbits and Bose-Einstein condensation in $^{12}$C

Detailed study of the cluster structure of light nuclei in a three-body model: (II). The spectrum of low-lying states of nuclei with A = 6

Detailed study of the cluster structure of light nuclei in a three-body model: (I). Ground state of 6Li

For pt.I see ibid., vol.8, no.5, p.667-78 (1982). The variational approach to calculations of multicluster systems which was developed in part I, is applied to a study of low-lying states with Jpi T=1+0 and 0+1 in nuclei with A=6. The interaction Hamiltonian includes the central spin-orbit and tensor forces. The effect of the Pauli principle is included through the requirement of orthogonality of the total wavefunction to the forbidden OS state in the n- alpha and p- alpha subsystems. The Coulomb interaction is included accurately. The P-component admixtures to the total wavefunction are studied. The value of the mathematical expectation of the 6Li Hamiltonian is shown to be relatively insensitive to the P-component contribution. The character of saturation in the pseudo-potential coupling constant corresponding to the contribution of the forbidden states is studied. The calculated Coulomb differences for the 6He-6Li-6Be isobaric triplet prove to be in rather good agreement with the experimental data, as are the value of the RMS radius and the behaviour of the charge form factor of the 6Li ground state.

A variational study of the ground and excited states of light nuclei in a three-body model on the complete basis. II. The structure of 6He-6Li-6Be nuclei in the α+2N model

P.B. Sazonov

Papers

Detailed study of the cluster structure of light nuclei in a three-body model: (II). The spectrum of low-lying states of nuclei with A = 6

Detailed study of the cluster structure of light nuclei in a three-body model: (I). Ground state of 6Li

A variational study of the ground and excited states of light nuclei in a three-body model on the complete basis. II. The structure of 6He-6Li-6Be nuclei in the α+2N model

The deuteron structure and NN-phase shifts for realistic local superdeep NN-potential with an extra state

The NN-potential with forbidden state suggested from a six-quark model with one-pion exchange