Narrow Results

A brief history of the continuum shell model with full correction for target recoil is provided. Past applications to nucleon induced reactions, nucleon capture, knockout reactions by pions and electrons, and strangeness exchange reactions are provided. Recent progress of the model is reviewed. Examples of continuum states for p-shell nuclei, derived from both two and three-body interactions, are given. Finally, the general model is presented in which any core states and any states of the composite system may be incorporated in a calculation.

In this work, we explore the possibility that the motion of the deuterium ions emitted from Coulomb cluster explosions is highly disordered enough to resemble thermalization. We analyze the process of nuclear fusion reactions driven by laser–cluster interactions in experiments conducted at the Texas Petawatt laser facility using a mixture of D₂+³He and CD₄+³He cluster targets. When clusters explode by Coulomb repulsion, the emission of the energetic ions is “nearly” isotropic. In the framework of cluster Coulomb explosions, we analyze the energy distributions of the ions using a Maxwell–Boltzmann (MB) distribution, a shifted MB distribution (sMB), and the energy distribution derived from a log-normal (LN) size distribution of clusters. We show that the first two distributions reproduce well the experimentally measured ion energy distributions and the number of fusions from d–d and d-³He reactions. The LN distribution is a good representation of the ion kinetic energy distribution well up to high momenta where the noise becomes dominant, but overestimates both the neutron and the proton yields. If the parameters of the LN distributions are chosen to reproduce the fusion yields correctly, the experimentally measured high energy ion spectrum is not well represented. We conclude that the ion kinetic energy distribution is highly disordered and practically not distinguishable from a thermalized one.

Rate constants of chemical reactions can be computed directly: employing flux correlation functions, no scattering calculations are required. If the reaction is direct, the dynamical simulation can be restricted to the vicinity of the reaction barrier. Therefore accurate thermal rate constants and cumulative reaction probabilities can be calculated for rather large systems. Recent calculations have studied systems with up to six atoms, e.g., H + CH₄ → H₂ + CH₃. The calculations provide a full-dimensional quantum description of the reaction process.

In the article, an introduction to the theory of flux correlation functions is given. Methods for the efficient computation of accurate thermal rate constants and cumulative reaction probabilities are reviewed. Connections to transition state ideas are highlighted. The multi-configurational time-dependent Hartree (MCTDH) approach, which facilitates efficient multi-dimensional wave packet propagation, is described and its use in reaction rate calculation is discussed. As examples, recent results for the prototypical polyatomic reaction H + CH₄ → H₂ + CH₃ are presented and rotational effects on the reaction rates of H₂ + OH → H + H₂O, O + HCl → OH + Cl, and H₂ + Cl → H + HCl are discussed.

The results of use of chemical kinetics receptions, approaches and methods for the study of porphyrins and their metal complexes reactivity are discussed on an example of oxidation, acid-basic, and catalytic reactions of rhodium, palladium, and rhenium complexes of porphyrin in liquid solutions. The peculiarity of the porphyrin reaction rates is analyzed in a brief context of general provisions of the chemical kinetics. The opportunity to use the quasistationarity principle at the definition of the kinetic equation of the reactions with participation of metal porphyrins is shown. The transition from the process kinetic description to consideration of its mechanism is explored.

In this talk, we report our main results on the study of the low-energy reactions K^-p → Σ⁰π⁰, Λπ⁰, , ηΛ in a quark model. This model might be a powerful approach to deal with these low-energy reactions. In the analysis, we find that the u- and t-channel backgrounds play crucial roles in the low-energy scatterings. Significant evidence of some low-lying Λ and Σ hyperon resonances in these processes are found. Furthermore, we obtain some properties of the low-lying Λ and Σ hyperon resonances. For example, Λ(1670)S₀₁ should have a much stronger coupling to ηΛ, while having a weaker coupling to than that derived in the SU(6) ⊗ O(3) limit; the coupling of Λ(1690)D₀₃ to ηΛ is very small. The configuration mixing effects might be crucial to understand the strong interaction properties of the low-lying negative Λ resonances.

Rare isotopes are most often studied through nuclear reactions. Nuclear reactions can be used to obtain detailed structure information but also in connection to astrophysics to determine specific capture rates. In order to extract the desired information it is crucial to have a reliable framework that describes the reaction process accurately. A few recent developments for transfer and breakup reactions will be presented. These include recent studies on the reliability of existing theories as well as effort to reduce the ambiguities in the predicted observables.