Effect of charge exchange collisions on the static properties of afully collisional ion sheath

The effect of charge exchange collisions on the properties of a fully collisional, static ion sheath is considered. The existing collisional law, which excludes the effect of electrons, is derived from the fluid equations. The effect of electrons are later considered and an approximate power law solution for the potential is obtained. The effect of collisionality on the sheath properties is discussed. The approximate power law solution, derived with the help of fluid equations, is applied to find the ion energy distribution at the electrode     

Double resonant charge exchange in ion-ion collisions

The process of resonant double charge exchange in low energy ion-ion collisions is considered. The effects of the Coulomb interaction of the nuclei are taken into account. Cross section calculations are performed both for completely and partially stripped projectile ions with 3? Z ? 10.     

Excitation of a singly charged barium ion in electron-atom collisions

Results of the experimental study of excitation of transitions of singly charged barium atoms in collisions of low-energy monokinetic electrons with barium atoms are presented. Regularities of the behavior of cross sections for excitation in spectral series of BaII are found. The results are compared with other authors’ results.     

Time scales for charge equilibration in heavy ion collisions

Charge equilibration was investigated in the reaction²⁰⁸Pb+¹¹⁰Pd at 1,180 and 1,280 MeV incident energy. It is found that the relaxation timeτ′ connected with this degree of freedom shows an increase with increasing bombarding energy. This behaviour can be explained within Langevin's classical theory of Brownian motion.     

A theoretical model for the charge equilibration in heavy ion collisions

We propose to treat the charge equilibration process as a collective high frequency mode and discuss the implications for the first stages of a heavy ion collision. We show how its dynamics can be treated by means of a quantal master equation. We solve numerically the dynamical equations for a two-dimensional model, using charge excess and mass asymmetry as dynamical degrees of freedom.     

Multicomponent transport theoretical approach to ultrarelativistic heavy ion collisions

A new theoretical model is introduced which is able to describe the initial compression and thermalization stage of an ultrarelativistic heavy-ion collision in a hydrodynamical three-flow picture. The first and second fluid is attributed to the nucleons of target and projectile, while a third component is introduced in order to take into account the gradual thermalization of the incoming flow. Based on relativistic transport theory, hydrodynamic equations of motion are derived for each component including transitions of target and projectile nucleons to the thermalized matter component as well as mutual deceleration accompanied with gradual heat transfer between the components. Hence, the multicomponent formalism contains the former two fluid approach as a limiting case.     

Resonant charge exchange in slow collisions involving halogens and oxygen

The coupling of electron momenta is considered for the resonant charge exchange process in slow collisions. Because the electron transfer in this process occurs at large distances between the colliding atomic particles, where ion-atom interactions are relatively weak, we can separate different types of interaction and find the character of coupling of the electron momenta in the quasi-molecule, consisting of the colliding ion and its atom, for real collision pairs. Since the real number of interaction types for colliding particles exceeds that used in the classical Hund coupling scheme, there are intermediate cases of momentum coupling outside the standard Hund scheme. This occurs for the resonant charge exchange involving halogens and oxygen where the quantum numbers of the quasi-molecule in the course of the electron transfer are the total momenta J and j of the colliding ion and atom and the projection M or M_J of the atom orbital or total momentum on the quasi-molecule axis. The ion-atom exchange interaction potential is independent of the ion fine state, and under these conditions, the resonant charge exchange process is not entangled with the rotation of electron momenta, as in case “a” of the Hund coupling. The partial cross section of the resonant charge exchange process depends on quantum numbers of the colliding particles. The average cross sections depend weakly on the coupling scheme.     

Simple approach for charge renormalization in highly charged macroions

We revisit the notion of renormalized charge, which is a concept of central importance in the field of highly charged colloidal or polyelectrolyte solutions. Working at the level of a linear Debye-Hückel-like theory only, we propose a versatile method to predict the saturated amount of charge renormalization, which is, however, a nonlinear effect arising at strong electrostatic coupling. The results are successfully tested against nonlinear Poisson-Boltzmann theory for polyions of various shapes (planar, cylindrical, and spherical), both in the infinite dilution limit or in confined geometry, with or without added electrolyte. Our approach, accurate for monovalent microions in solvents such as water, is finally confronted against experimental results on charged colloids and B-DNA solutions.     

New approach of fragment charge correlations in Xe+Sn central collisions

A previous analysis of the charge (Z) correlations in the ΔZ−Z plane for ¹²⁹Xe+^natSn central collisions at 32 MeV/n has shown an enhancement in the production of equally sized fragments (low ΔZ) which was interpreted as an evidence for spinodal decomposition. However, the signal is weak and rises the question of the estimation of the uncorrelated yield. After a critical analysis of its robustness, we propose in this paper a new technique to build the uncorrelated yield in the charge correlation function. The application of this method to ¹²⁹Xe+^natSn central collision data at 32, 39, 45 and 50 MeV/n does not show any particular enhancement of the correlation function in any ΔZ bin.     

Correlation between the fragmentation modes and light charged particles emission in heavy ion collisions

The correlation between the shape of rapidity distribution of the yield of light charged particles and the fragmentation modes in semi-peripheral collisions for70Zn+70Zn,64Zn+64Zn and64Ni+64Ni at the beam energy of 35 Me V/nucleon is investigated based on Im QMD05 code. Our studies show there is an interplay between the binary, ternary and multi-fragmentation break-up modes.The binary and ternary break-up modes more prefer to emit light charged particles at middle rapidity and give larger values of Rmid yieldcompared with the multi-fragmentation break-up mode does. The reduced rapidity distribution for the normalized yields of p, d, t,3He,4He and6 He and the corresponding values of Rmid yieldcan be used to estimate the probability of multi-fragmentation break-up modes. By comparing to experimental data, our results illustrate that 40% of the collisions events belong to the multifragmentation break-up mode for the reactions we studied.