Gamow peak approximation near strong resonances

We discuss the most effective energy range for charged particle induced reactions in a plasma environment at a given plasma temperature. The correspondence between the plasma temperature and the most effective energy should be modified from the one given by the Gamow peak energy, in the presence of a significant incident-energy dependence in the astrophysical S-factor as in the case of resonant reactions. The suggested modification of the effective energy range is important not only in thermonuclear reactions at high temperature in the stellar environment, e.g., in advanced burning stages of massive stars and in explosive stellar environment, as it has been already claimed, but also in the application of the nuclear reactions driven by ultra-intense laser pulse irradiations

Bound Electron Screening Corrections to Reactions in Hydrogen Burning Processes

How important would be a precise assessment of the electron screening effect, on determining the bare astrophysical $S$-factor ($S_b(E)$) from experimental data? We compare the $S_b(E)$ obtained using different screening potentials, (1) in the adiabatic limit, (2) without screening corrections, and (3) larger than the adiabatic screening potential in the PP-chain reactions. We employ two kinds of fitting procedures: the first is by the conventional polynomial expression and the second includes explicitly the contribution of the nuclear interaction and based on a statistical model. Comparing bare $S$-factors that are obtained by using different screening potentials, all $S_b(E)$ are found to be in accord within the standard errors for most of reactions investigated, as long as the same fitting procedure is employed. $S_b(E)$ is, practically, insensitive to the magnitude of the screening potential.Comment: 13 pages, 5 figure

Isospin Effects on Astrophysical S-Factors

We estimate the ratios of bare astrophysical S-factors at zero incident energy for proton and deuteron induced reactions in a model which assumes a compound nucleus formation probability plus a statistical decay. The obtained ratios agree well with available experimental values, as far as the reactions which have dominant s-wave entrance channel components are investigated. Due to its simplicity the model could be used as a guidance for predictions on reactions which have not been investigated yet.Comment: 12 pages, 1 figure

Application of the X-ray laser to muon-catalyzed d-t fusion

We discuss the alpha-muon sticking coefficient in the muon-catalysed d-t fusion in the framework of the Constrained Molecular Dynamics model. Especially the influence of muonic chaotic dynamics on the sticking coefficient is brought into focus. The chaotic motion of the muon affects not only the fusion cross section but also the muon-alpha sticking coefficient. Chaotic systems lead to lar ger enhancements with respect to regular systems because of the reduction of the tunneling region. Moreover they give smaller sticking probabilities than those of regular events. By utilizing a characteristic of the chaotic dynamics one can avoid losing the muon in the muCF cycle. W e propose that the application of the so-called microwave ionization of a Rydberg atom to the present case could lead to the enhancement of the reactivation process by using X-rays