[en] We investigate the ³¹Ne and ³²Ne neutron-rich nuclei by using the Generator Coordinate Method. The wave functions are defined by a ³⁰Ne + n and ³⁰Ne + n + n cluster structure, respectively. The binding energies of both systems are studied with different parameters of the nucleon-nucleon interaction, and are shown to be similar. Assuming the particle stability of ³²Ne, the ³¹Ne nucleus is therefore predicted to be stable with respect to neutron decay. Spectroscopic properties (r.m.s. radii and E2 transition probabilities) are presented for both nuclei

[en] The ⁸B(p,γ)⁹C, ¹¹C(p,γ)¹²N and ¹³N(p,γ)¹⁴O capture cross sections are investigated in a microscopic cluster model, with a full p-shell description of the target nuclei. For the ⁸B(p,γ)⁹C reaction and its mirror, the E1 and E2 components are analyzed. The present model confirms previous microscopic calculations for ⁸B(p,γ)⁹C and ¹³N(p,γ)¹⁴O, but yields a significant reduction of the ¹¹C(p,γ)¹²N reaction rate. In each case, the sensitivity with respect to the nucleon-nucleon interaction is evaluated, and shown to be weak

[en] We investigate the ¹⁵N(α,γ)¹⁹F and ¹⁵O(α,γ)¹⁹Ne reactions by using a multicluster description of ¹⁵N and ¹⁵O. The ¹⁵N(α,γ)¹⁹F and ¹⁵O(α,γ)¹⁹Ne wave functions are defined in the Generator Coordinate Method, using α and triton (or ³He) wave functions. The band structure and the E2 transition probabilities are well reproduced by the model, but some resonances, important for astrophysics, are missing. The non-resonant part of the ¹⁵N(α,γ)¹⁹F and ¹⁵O(α,γ)¹⁹Ne capture cross sections is discussed

[en] The ^15,17,19 C neutron-rich isotopes are investigated with the Generator Coordinate Method, involving ^14,16,18 C + n configurations. Core excitations are taken into account and are shown to play an important role for several states. The ¹⁵ C nucleus is used as a test case. Analysis of spectroscopic properties provides a 1/2⁺ assignment for the ¹⁹ C ground state. For ¹⁷ C, both 1/2⁺ and 3/2⁺ spins are possible. The theoretical ¹⁹ C Coulomb photodissociation cross section is in good agreement with experiment. We suggest that a similar experiment with ¹⁷ C would provide valuable information about the spin. An exploratory study of ²¹ C shows that this nucleus could be particle stable with a spin 1/2⁺

No abstract available

[en] A microscopic three-cluster model is used to investigate the ¹²C, ²⁴Mg and ⁴⁸Cr nuclei, described by α+α+α, ¹⁶O+α+α and ⁴⁰Ca+α+α configurations, respectively. For each system, a fairly good agreement with experiment is obtained. We essentially focus on the ⁴⁸Cr nucleus for which a band structure is suggested. In addition to the well-known ground-state band, we predict the existence of additional bands

[en] Short communication

[en] The ¹⁶O spectrum is investigated microscopically in a multiconfiguration generator-coordinate basis, including the α+¹²C(0⁺), α+¹²C(2⁺), p+¹⁵N(1/2^-) and n+¹⁵O(1/2^-) configurations. This choice allows a microscopic description of T=1 states and of isospin impurities in low-lying states of the ¹⁶O nucleus. The model reproduces most of the T=0 and T=1 states below 14 MeV excitation energy. Different bands are suggested, for which valuable experimental candidates exist. A satisfactory agreement with experiment is obtained for the E1, E2 and M1 transition probabilities. (orig.)

[en] We report on a microscopic description of low-energy nuclear reactions, in the framework of the Generator Coordinate Method. The model is briefly presented and illustrated by applications to the ⁷Li(n,γ)⁸Li, ⁷Be(pγ)⁸B, and ¹²C(α,γ)¹⁶O capture reactions and to the ⁸Li(α,n)¹¹B transfer reaction. (Author)

[en] The hyperspherical formalism is applied in the framework of the microscopic generator-coordinate method. Three-cluster systems are described with a single generator coordinate, the hyperradius. This model is a natural extension of previous microscopic theories, and can be applied to bound states and resonances in a range of nuclei exhibiting a cluster structure. As an illustrative example, the model is applied to ⁶He and ⁶Li. Density distributions and electric dipole transition strengths are calculated, including B(E2;0⁺→2⁺) in ⁶He. The results are consistent with a neutron halo structure for the ground state of ⁶He, and with a proton-neutron halo structure of its isobaric analog state in ⁶Li. No 1^- 'soft dipole' resonance is found in ⁶He