Three-cluster model of radiative capture reactions in seven-nucleon systems. Effects of cluster polarization
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NUCLEI Theory
Three-Cluster Model of Radiative Capture Reactions in Seven-Nucleon Systems. Effects of Cluster Polarization* V. S. Vasilevsky**, A. V. Nesterov*** , and T. P. Kovalenko**** Bogolyubov Institute for Theoretical Physics, Kiev, Ukraine Received August 4, 2011; in final form, October 19, 2011
Abstract—We apply the microscopic three-cluster model, developed by the authors recently, to study the effects of cluster polarization on the capture reactions 3 He(α, γ)7 Be, 3 H(α, γ)7 Li, 6 Li(p, γ)7 Be, and 6 Li(n, γ)7 Li. These reactions are of great importance for astrophysical applications. Thus, the main attention is paid to the cross sections (or the astrophysical S factor) of the reactions in the low-energy region. Correlations between the astrophysical S factor of the reactions at zero energy and different quantities associated with the ground state of a compound nucleus are studied in detail. DOI: 10.1134/S106377881204014X
INTRODUCTION The aim of the present work is to study how strongly the cluster polarization affects the cross sections or astrophysical S factor of the capture reactions 3 He(α, γ)7 Be, 3 H(α, γ)7 Li, 6 Li(p, γ)7 Be, and 6 Li(n, γ)7 Li in 7 Be and 7 Li nuclei. This investigation is stimulated by two circumstances. First, the radiative capture and photonuclear reactions are a source of interesting and valuable information about the dynamics and the structure of nuclear systems. This information is of great importance for fundamental and applied investigations. It is well known that the cross sections of radiative capture and photodisintegration reactions (within the standard approximations) are determined by the wave functions of bound and continuous-spectrum states of a compound nucleus. Thus, these reactions are a good testing site for numerous microscopic and semimicroscopic models to check the quality of wave functions obtained within the models. This test verifies both the internal and asymptotic parts of wave functions. On the other hand, these reactions are a basic stage of processes running inside the Sun and other stars and in the Universe. Astrophysical aspects of the reactions under consideration (related, for instance, to the problem of solar neutrino and the abundance of light elements in the Universe after the Big Bang) are thoroughly discussed in [1–6]. Thus, ∗
The text was submitted by the authors in English. E-mail: [email protected] *** E-mail: [email protected] **** E-mail: [email protected] **
the theoretical analysis of the reactions is of great importance for understanding and revealing main factors, which have a great impact on the processes, and for predicting a behavior of the cross sections of these reactions in the energy range dominating in the Sun and the Universe. Numerous experiments have been performed [7–18] to determine the astrophysical S factor of the reactions at energies that are relevant to astrophysical applications. Moreover, the huge theoretical efforts have been applied within microscopic and semimicroscopic methods (see, e.g., [19–37]) to a
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