Application of a two-step dynamical model to calculating properties of fusion-fission reactions
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CLEI Theory
Application of a Two-Step Dynamical Model to Calculating Properties of Fusion–Fission Reactions G. I. Kosenko1)* , F. A. Ivanyuk2), V. V. Pashkevich3), and D. V. Dinner1) Received February 13, 2008; in final form, May 27, 2008
Abstract—The two-step model of fusion–fission reactions that was proposed previously by the present authors is extended in such a way as to describe the multiplicity of light particles emitted from nuclearfission fragments. Calculations are performed for the reaction induced by 48 Ca + 244 Pu collisions. The mass distribution of fragments, their mass–energy distribution, and the total multiplicity of neutrons and gamma rays are obtained for Elab = 230, 238, 249, and 255 MeV. It is shown that the model reproduces qualitatively relevant experimental data. In order to attain quantitative agreement, it is necessary to take into account the angular momentum carried away by particles from the nucleus undergoing fission and various types of gamma rays emitted by the nucleus and its fission fragments. PACS numbers: 05.10.Gg, 25.70.-z, 25.70.Jj DOI: 10.1134/S1063778808120065
1. INTRODUCTION The physics of fusion–fission nuclear processes has long been the subject of vigorous experimental investigations. Since the discovery of reactions induced by deep-inelastic collisions [1], it has become clear that the formation of a compound nucleus is an intricate process. The effect of the entrance channel on properties of decay products was studied in [2, 3]. The fact that there is an intimate relation between fission reactions and reactions involving the synthesis of new elements was indicated back in [4]. The importance of studying neutrons emitted by a nucleus undergoing fission and, after that, by its fission products was highlighted in the review article of Newton [5]. He also emphasized that it would be of interest to take into consideration protons, alpha particles, and gamma rays emitted in the fission process. The experimental studies reported in [6–8] furnished a vast body of information about the multiplicities of light particles emitted in heavy-ion reactions. The fragment-mass dependences of the multiplicities of these particles were obtained there. The investigations in question covered reactions leading to the synthesis of superheavy elements. The importance of studying the fusion–fission process starting from the 1)
Omsk State University, pr. Mira 55A, Omsk, 644077 Russia. 2) Institute for Nuclear Research, National Academy of Sciences of Ukraine, pr. Nauki 47, 03680 Kyiv, Ukraine. 3) Joint Institute for Nuclear Research, Dubna, Moscow oblast, 141980 Russia. * E-mail: [email protected]
point at which the ions involved come into contact was indicated in [5]. One of the first attempts at taking into account the effect of the entrance channel was undertaken in [9], where the effect of the point of stopping of the relative motion of participant ions on the probability of compound-nucleus formation was studied. A method for describing fusion–fission reactions on the basis of a two-step mode
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