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Origine dynamique de la multifragmentation nucléaire

Abstract : The study of the peripheral and semi-peripheral collisions in the reaction Xe+Sn at 50 A.MeV has lead to the identification of the role of out-of-equilibrium aspects in the production of intermediate mass fragments (IMF). First, it is shown that the experimental observations are incompatible with a model in which a very hot layer of matter is primarily responsible for the production of IMF at intermediate velocity. Next, the same data are compared with a calculation using the quantum molecular dynamics approach (QMD). the quality of agreement with the predictions of this model allows to draw conclusions concerning the production mechanism of fragments. The IMF originate from region that is intermediate between the projectile and the target. It is furthermore shown that this region is not in thermal equilibrium, that the fragments are pre-formed and that their velocity and composition strongly depend on the initial conditions of the reaction. The quasi-projectile and the quasi-target, on the other hand, are only mildly influenced by the collision and their excitation energies are estimated to be below the limit at which multifragmentation will take place. In parallel, an analysis is carried out which correlates he multiplicity of the IMF with the violence of the collision. This shows that a proper analysis of a process as complex as nuclear multifragmentation must simultaneously involve kinetic variables (velocity, energy,...) as well as static ones (multiplicity. charge distribution,...).
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Submitted on : Wednesday, January 14, 2015 - 11:39:12 AM
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  • HAL Id : in2p3-00008666, version 1

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Olivier Tirel. Origine dynamique de la multifragmentation nucléaire. Physique Nucléaire Expérimentale [nucl-ex]. Université de Caen, 1998. Français. ⟨in2p3-00008666⟩

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