[en] A wide range of phenomena is observed in heavy-ion collisions, calling for a comprehensive theory based on fundamental principles of many-particle quantum mechanics. At low energies, the nuclear dynamics is controlled by the mean field, as we know from spectroscopic nuclear physics. We therefore expect the comprehensive theory of collisions to contain mean-field theory at low energies. The mean-field theory is the subject of the first lectures in this chapter. This theory can be studied quantum mechanically, in which form it is called TDHF (time-dependent Hartree-Fock), or classically, where the equation is called the Vlasov equation. 25 references, 14 figures

[en] There are two quite different mathematical representations of the RPA, namely the response-function formalism and the A, B-matrix formulation. The program presented in this chapter has as its primary focus the resonances in the continuum, and it uses the response-function method. (orig./HSI)

No abstract available

[en] This work deals with the halation nuclei. Atomic nuclei rich in neutrons and protons are surrounded by an halation. Their studies inform us on the nuclear cohesion strengths. The answer to the question : how neutrons and protons combine to form halation nuclei is given in the first part. Then are reported the experiments carried on the lithium 11 nuclei. The third part is a description of the different theories given on the matching of two halation neutrons. The last part speaks about the future of halation. (O.L.). 5 refs., 5 figs

[en] Atomic nuclei containing a lot of protons and neutrons are surrounded by a halo. Their study inform us on the strengths of nuclear cohesion. (authors)

[en] Spectroscopic properties of nuclei are accessible with projectile fragmentation reactions, but approximations made in the reaction theory can limit the accuracy of the determinations. We examine here two models that have rather different approximations for the nucleon wave function, the target interaction, and the treatment of the finite duration of the reaction. The nucleon-target interaction is treated differently in the eikonal and the transfer-to-continuum model, but the differences are more significant for light targets. We propose a new parametrization with that in mind. We also propose a new formula to calculate the amplitudes that combines the better treatment of the wave function in the eikonal model with the better treatment of the target interaction in the transfer-to-continuum model

[en] Projectile fragmentation reactions are well suited to structure studies of weakly bound nuclei, but an accurate reaction theory is necessary to extract quantitative spectroscopic properties. We examine here the accuracy of the commonly used eikonal approximation for the nuclear-induced breakup of halo nuclei. Comparing to numerical solutions of the full time-dependent Schroedinger equation, we find that the eikonal remains fairly accurate for calculating breakup probabilities of halo nuclei even down to 20 MeV/nucleon, reproducing relative spectroscopic strengths to within a few percent. Absolute reaction probabilities tend to be underpredicted by the eikonal, which would make extracted spectroscopic strengths somewhat too high. We discuss other features that are seen in the full calculation but are missing in the eikonal approximation such as the ''towing'' mode

[en] Fragmentation reactions offer a useful tool to study the spectroscopy of halo nuclei, but the large extent of the halo wave function makes the reaction theory more difficult. The simple reaction models based on the eikonal approximation for the nuclear interaction or first-order perturbation theory for the Coulomb interaction have systematic errors that they investigate here, comparing to the predictions of complete dynamical calculations. They find that stripping probabilities are underpredicted by the eikonal model, leading to extracted spectroscopy strengths that are two large. In contrast, the Coulomb excitation is overpredicted by the simple theory. They attribute this to a screening effect, as is well known in the Barkas effect on stopping powers. The errors decrease with beam energy as E(sub beam)(sup -1), and are not significant at beam energies above 50 MeV/u. At lower beam energies, the effects should be taken into account when extracting quantitative spectroscopic strengths

[en] We calculate the different nuclear breakup cross sections (diffraction, stripping and absorption) within the Serber model for single-nucleon as well as two-neutron halos (so-called Borromean nuclei). In contrast to calculations up to now, we use realistic wave functions as well as a realistic model for the interaction with the target. We show results of our calculations for total as well as differential cross sections

[en] The Institute for Nuclear Theory was created as a national center by the Department of Energy. It began operations March 1, 1990. This annual report summarizes the INT's activities during its fourth year of operations