Adiabatic hyperspherical study of triatomic helium systems

The 4He3 system is studied using the adiabatic hyperspherical representation. We adopt the current state-of-the-art helium interaction potential including retardation and the nonadditive three-body term, to calculate all low-energy properties of the triatomic 4He system. The bound state energies of the 4He trimer are computed as well as the 4He+4He2 elastic scattering cross sections, the three-body recombination and collision induced dissociation rates at finite temperatures. We also treat the system that consists of two 4He and one 3He atoms, and compute the spectrum of the isotopic trimer 4He2 3He, the 3He+4He2 elastic scattering cross sections, the rates for three-body recombination and the collision induced dissociation rate at finite temperatures. The effects of retardation and the nonadditive three-body term are investigated. Retardation is found to be significant in some cases, while the three-body term plays only a minor role for these systems.Comment: 24 pages 6 figures Submitted to Physical Review

ATOMES DE RYDBERG EN PRESENCE DE CHAMPS ELECTRIQUES ET MAGNETIQUES PARALLELES

PARIS-BIUSJ-Physique recherche (751052113) / SudocCentre Technique Livre Ens. Sup. (774682301) / SudocSudocFranceF

Cross Section Database for Carbon Atoms and Ions: Electron-impact Ionization, Excitation, and Charge Exchange in Collisions with Hydrogen Atoms

A database have been constructed for the recommended cross sections on electron-impact excitation and ionization of carbon atoms and ions C, C^+-C^5+, as well as charge-exchange processes between carbon ions C^+-C^6+ and hydrogen atoms. We have collected a large amount of theoretical and experimental cross section data from the literature, and have critically assessed their accuracy. The recommended cross sections, the best values for use, are expressed in a form of simple analytical functions. These are also presented in graphical form

Precise calculation of the triple- α reaction rates using the transmission-free complex absorbing potential method

We study the triple-α reaction process at low temperatures, which is known to play an important role in stellar physics. The Schrödinger equation for three α particles is solved by using hyperspherical coordinates, while a complex absorbing potential is introduced in order to describe correctly the three-body continuum states. We use an angular-momentum-independent α-α potential and introduce three-body potentials to reproduce the energies of both the Hoyle state and the first 2+ state. The triple-α reaction rate is computed accurately at temperatures from T=0.01 to 10 GK and compared with those available in the literature. Our reaction rate is found to be up to three orders of magnitude larger than the NACRE rate at low temperatures T≈0.01 GK, while we find a reasonable agreement between them at higher temperatures T 0.1 GK.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Triple-α continuum structure and Hoyle resonance of C 12 using the hyperspherical slow variable discretization

We develop a method for calculating the bound and continuum energy spectrum of three particles interacting through both short-range and Coulomb potentials. Our method combines hyperspherical coordinates with the slow variable discretization approach. A complex absorbing potential is employed to describe accurately the continuum wave functions. The method is well known in atomic and molecular physics. It is extended here to nuclear physics, with a special emphasis on the long-range Coulomb interaction. The method is applied to compute the energy spectrum of C12 in a 3α-particle model, focusing on an accurate calculation of the Hoyle resonance width of the narrow near-threshold Jnπ=02+ state, which plays an important role in stellar nucleosynthesis. We employ an effective α-α interaction potential which reproduces both the energy and width of Be8, while a three-body force is added in order to fix the C12 energy levels at the experimental values. We also analyze the structure of the bound and resonance states by calculating the wave functions and one-dimensional distribution functions.SCOPUS: ar.jinfo:eu-repo/semantics/publishe