Production of A+1 and Z+1 Isotopes in Proton-Induced Reactions on AZ Nuclei. Application to Po Production in p-209Bi and Bi Production in p-208Pb Reactions

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Amélioration du modèle de cascade intranucléaire de Liège en vue de l'étude de cibles de spallation pour les systèmes hybrides

L’intérêt pour les réactions de spallation comme source intense de neutrons s’est renouvelé ces dix dernières années avec les études de transmutation des actinides mineurs dans les systèmes hybrides (ADS).Parmi les modèles de réaction de spallation, le modèle de cascade intranucléaire de Liège (INCL), couplé au modèle d’évaporation ABLA, s’est révélé être l’un des plus prédictifs pour des nucléons incidents de 200 MeV à quelques GeV.Cependant le modèle INCL présente encore quelques lacunes et fait donc encore l’objet de développements. Dans cette thèse nous avons tenté de remédier aux points suivants:- évaluation du pic quasi-élastique en introduisant la dépendance en isospin et en énergie du champ nucléaire moyen des baryons,- les voies faisant intervenir les pions en étendant les sections efficaces pion-nucléon de part et d’autre de la résonnance D et en introduisant un potentiel moyen pour les pions déterminé par ajustement sur de nombreuses données expérimentales de production de pions et induites par des pions.En vue de l’extension du modèle INCL aux basses énergies nous avons également comparé ce modèle à des modèles de prééquilibre, en théorie mieux adaptés pour des énergies incidentes comprises entre 10 et 200 MeV.Finalement nous avons étudié l’impact de nos investigations pour l’étude de cibles de spallation épaisses et d’ADS.Le résultat le plus important de nos recherches tant pour des cibles minces que pour la conception de cibles épaisses, est une nette amélioration (réduction) de l’estimation des isotopes hautement radiotoxiques du Po à partir de cibles en Bi

Theoretical Description of Proton and Light Ion-Induced Reactions within the HINDAS Collaboration

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Effects of isospin and energy dependences of the nuclear mean field in spallation reactions

In many applications of the intranuclear-cascade (INC) model to spallation reactions, all nucleons in the target are assumed to move in a common potential well. However, the potential depth should depend upon nucleon isospin and energy. The present paper describes the first results obtained after the introduction of these features in the Liege INCL3 model. It is shown that such modifications change cascade particle multiplicities significantly but total particle multiplicities are only slightly altered. Nucleon inclusive cross-sections are not modified significantly, except in the region of the quasi-elastic peaks. In particular, the centroid of the peak in neutron double differential cross-sections relative to proton-induced reactions can be sizeably shifted toward larger energy losses, as is observed experimentally. Implications of these results are discussed

Pion physics in the Liege intranuclear cascade model

The implementation of pi production in the Liege intranuclear cascade model (INCL4) for spallation reactions is revisited to alleviate the overestimate of the pi yield. Three modifications are proposed for this purpose: a better pi N cross section at high energy, the introduction of a pi average potential, and the modification of the average mass of the Delta resonance. The pi potential is determined from a global fit of a set of data bearing on pi production in proton-induced reactions, on pi-nucleus and absorption cross sections, and on proton production in pi-induced reactions. The resulting pi potential is poorly determined in the nuclear interior and agrees with the phenomenological optical-model potentials in the surface region. With these modifications, the predictions of the INCL4 model concerning pi production cross sections in proton-induced reactions are considerably improved. Predictions of the improved version for pi-nucleus reaction and absorption cross sections and for proton, residue, and fission cross sections in pi-induced reactions are also presented and shown to give reasonably good agreement. Neutron production and some aspects of fission in pi-induced reactions are also investigated and reasonably well predicted. Effects on the modifications on observables, which are not directly linked with pi's, such as the neutron yield and the residue mass and charge spectra in proton-induced reactions are also investigated and shown to improve the description of these observable quantities. Several results on pi production and the relative insentivity to the pi potential in the nuclear interior are shown to be consistent with the fact that most pi's are not produced in early collisions. Importance of rescattering in pi absorption on nuclei is also pointed out. A comparison is made with the so-called Delta-hole model. Residual discrepancies are identified and are interpreted as due to the lack of pi interaction with two nucleons at low energy, to the neglect of quantum motion effects, and to a possible underestimate of rescattering

Spallation Reactions with Neutron-Rich and Neutron-Poor Nuclei

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Recent Progress of the Liège Intranuclear Cascade Model

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Influence of the Nucleon and Pion Mean Fields on the Description of Spallation Reactions

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Fission in Spallation Reactions Seminar on Fission, cientific, 2008, 241-258

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