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AbstractAbstract
[en] The last theoretical developments concerning the fusion process are reviewed. They concern the appearance of new dissipative mechanisms: fast fission, when the fission barrier of the compound nucleus vanishes due to angular momentum, and quasifission which takes place for heavy systems. The conditions under which these processes, as well as fusion, occur are discussed in details using the fast fission and the extra push models
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Sep 1983; 23 p; International conference on nuclear physics; Florence (Italy); 29 Aug - 3 Sep 1983
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AbstractAbstract
[en] Few typical examples of reaction mechanisms observed in heavy ion collisions at low, medium and high bombarding energies are presented. The present paper is primarily addressed to non specialists in the field. 18 refs
[fr]
Nous presentons quelques exemples typiques de mecanismes de reaction observes lors de la collision entre 2 noyaux lourds a basse, moyenne et haute energie. Tout au long de l'expose nous avons essaye de nous adresser aux non specialistes du domaine ce qui a conduit a schematiser quelque peu l'explication des phenomenes observes. 18 refs.Original Title
Dynamique de la voie d'entree
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Sep 1985; 9 p; Congress of the French Physical Society; Nice (France); 9-13 Sep 1985; DPH-N-S--2302
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[en] We review the conditions under which two heavy ions can fuse together. Then we discuss fast fission mechanism which is an intermediate mechanism between inelastic and compound nucleus reactions
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Apr 1983; 12 p; Seminar on heavy ion physics; Alushta (USSR); 14-21 Apr 1983
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[en] Recent experimental data on fusion which call for a better understanding are reviewed. A macroscopic dynamical model allowing to understand these data is described. In this approach a phenomenon intermediate between deep inelastic reactions and compound nucleus formation appear: fast fission. The conditions under which fast fission can be observed, as well as its properties are discussed. A comparison with another approach of the same problems is made: the extrapush model. Finally a simple dynamical model of fusion is reviewed which reproduces pretty well a large number of experimental fusion excitation functions
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Feb 1984; 20 p; Winter college on fundamental nuclear physics; Trieste (Italy); 7 Feb - 30 Mar 1984
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[en] In these notes we review, in a schematic way, some aspect of the physics with heavy ions. In the first lecture we review how is possible to describe the dissipative phenomena observed above the Coulomb barrier, up to 10-15 MeV/u, using transport theories. The second lecture is devoted to the question of fusion and the appearance of a new mechanism: fast fission. It is shown that one can now have a global understanding of these phenomena within single picture. The third lecture presents, in a simplified way, some results obtained recently with heavy ions in the range of 30-50 MeV/u at GANIL and SARA
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Jul 1984; 50 p; Course on frontiers and nuclear dynamics; Erice (Italy); 16-27 Jul 1984; DPH-N-S--2181
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ARGON 40 REACTIONS, CHARGED-PARTICLE TRANSPORT THE, DEEP INELASTIC SCATTERING, ENERGY LOSSES, FAST FISSION, FISSION FRAGMENTS, GEV RANGE 01-10, GOLD 197 TARGET, HEAVY ION FUSION REACTIONS, HEAVY ION REACTIONS, KRYPTON 84 REACTIONS, LECTURES, LINEAR MOMENTUM TRANSFER, MEV RANGE 100-1000, NEON 20 REACTIONS, QUASI-FISSION, REVIEWS, URANIUM 238 TARGET
BARYON REACTIONS, DOCUMENT TYPES, ENERGY RANGE, FISSION, GEV RANGE, HADRON REACTIONS, INELASTIC SCATTERING, INTERACTIONS, LEPTON-BARYON INTERACTIONS, LEPTON-HADRON INTERACTIONS, LEPTON-NUCLEON INTERACTIONS, MEV RANGE, MOMENTUM TRANSFER, NEUTRON REACTIONS, NUCLEAR FRAGMENTS, NUCLEAR REACTIONS, NUCLEON REACTIONS, NUCLEOSYNTHESIS, PARTICLE INTERACTIONS, SCATTERING, SYNTHESIS, TARGETS, TRANSPORT THEORY
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AbstractAbstract
[en] Some aspects of heavy-ion physics between approximately 20-50 MeV/u are reviewed on two examples. First, one describes the present situation concerning the amount of linear momentum that a projectile can transfer to a fused system. One shows that this amount depends on the bombarding energy and on the mass of the projectile. The limit of incomplete fusion is discussed in terms of the maximum energy content of a nuclear system. Second, one describes some new results obtained with Kr projectiles on medium and heavy targets where one observes strongly inelastic events. These products are interpreted qualitatively in terms of a participants-spectators picture modified by the mean field interaction. The difference between Kr and lighter projectiles induced reactions is interpreted in terms of the Coulomb interaction as it is also the case at low bombarding energies
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Oct 1985; 20 p; Topical meeting on phase space approach to nuclear dynamics; Trieste (Italy); 30 Sep - 4 Oct 1985; DPH-N-S--2303
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ANGULAR CORRELATION, ARGON 40 REACTIONS, COULOMB FIELD, DEEP INELASTIC HEAVY ION REACT, ENERGY DEPENDENCE, EXCITATION, GEV RANGE 01-10, GOLD 197 TARGET, INCOMPLETE FUSION REACTIONS, KINETIC ENERGY, KRYPTON 84 REACTIONS, LINEAR MOMENTUM TRANSFER, MASS, MEV RANGE 100-1000, MOLYBDENUM 98 TARGET, NUCLEAR FRAGMENTS, URANIUM 238 TARGET
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AbstractAbstract
[en] Heavy ions like Ar or Kr are now available at bombarding energies between approximately 20 and 50 MeV/u at GANIL or SARA. They can be used to investigate what happens when a heavy projectile interacts by nuclear forces with a heavy target. In these lectures we shall try to present some aspects of these results and see whether some general features emerge in this bombarding energy region. In the first lecture we shall summarize the results which have been obtained in the experiments where one looks at how much linear momentum the projectile can transfer to a fused system. In the second lecture we shall describe very recent results obtained with Kr projectiles. Finally, in the last part we shall investigate, from the theoretical point of view, whether nuclei could be mechanically unstable. This will be done in the framework of a time dependent Thomas Fermi approach. We shall see that compression, can be a cause of mechanical instability
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Apr 1985; 25 p; Course on nucleus-nucleus collisions from the Coulomb barrier up to the quark-gluon plasma; Erice (Italy); 10-22 Apr 1985; DPH-N-S--2275
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ARGON 40 REACTIONS, BISMUTH 209 TARGET, GEV RANGE 01-10, GOLD 197 TARGET, HEAVY ION FUSION REACTIONS, INCOMPLETE FUSION REACTIONS, KRYPTON 84 REACTIONS, LEAD 208, LECTURES, LINEAR MOMENTUM TRANSFER, MEV RANGE 100-1000, MOLYBDENUM 92 TARGET, MOLYBDENUM 98 TARGET, NEON 20 REACTIONS, NUCLEAR MATTER, NUCLEAR TEMPERATURE, SILVER 108 TARGET, THOMAS-FERMI MODEL, URANIUM 238 TARGET
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[en] We review the following aspects of fusion ractions in the tandem energy region: the experimental definition of the fusion, the experimental techniques to measure fusion sections, the analysis of the data in terms of critical angular momentum, the static and dynamical interpretations of the fusion process
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Mar 1983; 19 p; International symposium on nuclear physics at large tandem accelerators; Padua (Italy); 16-18 Mar 1983; 27 refs.
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[en] Review of a recent theoretical approach to heavy ion fusion above the Coulomb barrier. Presentation of a simple dynamical model which allows to well reproduce a lot of experimental data. It is shown that the fusion cross section is governed by a dynamical barrier which is, in some cases, different from the static one. Then we investigate what happens to the fused system. It is shown that some of the unexplained experimental data can be understood by the occurence of a new mechanism: fast fission. Its properties are discussed and we give the conditions of occurence for such a mechanism
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Sep 1984; 19 p; International symposium on heavy ion fusion reactions; Tsukuba (Japan); 3-7 Sep 1984; DPH-N--2186
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AbstractAbstract
[en] These lectures describe the properties of dissipative heavy ion collisions observed in low bombarding energy heavy ion reactions. These dissipative collisions are of two different types: fusion and deep inelastic reactions. Their main experimental properties are described on selected examples. It is shown how it is possible to give a simple interpretation to the data. A large number of phenomenological models have been developped to understand dissipative heavy ion collisions. The most important are those describing the collision by classical mechanics and friction forces, the diffusion models, and transport theories which merge both preceding approaches. A special emphasis has been done on two phenomena observed in dissipative heavy ion collisions: charge equilibratium for which we can show the existence of quantum fluctuations, and fast fission which appears as an intermediate mechanism between deep inelastic reactions and compound nucleus formation
[fr]
Ce cours decrit les proprietes des reactions dissipatives observees dans la collision de deux noyaux lourds a basse energie. Ces reactions dissipatives sont de deux types: la fusion ou les reactions tres inelastiques. Les principales proprietes experimentales de ces phenomenes sont decrites a l'aide d'exemples choisis. Il est montre comment il est possible d'interpreter de facon simple ces resultats. Un grand nombre de modeles phenomenologiques ont ete developpes pour interpreter ces collisions dissipatives. Les principaux sont ceux decrivant la collision par la mecanique classique et des forces de friction, les modeles de diffusion et les theories de transport qui permettent de faire la synthese des deux approches precedentes. Une mention toute particuliere a ete faite a deux phenomenes observes dans les collisions dissipatives: l'equilibre de charge ou l'on peut mettre en evidence des fluctuations de type quantique, et la fission rapide qui est un mecanisme intermediaire entre les reactions tres inelastiques et la formation d'un noyau composeOriginal Title
Approches phenomenologiques des collisions dissipatives entre ions lourds a basse energie
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Sep 1983; 320 p
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