Angular and Energy Distributions of Electrons Emitted from Gases and Thin Foils During Light Ion Bombardment

The energy and angular distributions of electrons ejected by fast charged particles in ionizing collisions provide detailed information regarding the effects of atomic, molecular, and condensed-phase structure on the energy loss process. Analysis of the wide range of available data has lead to several general conclusions. For ionization of atomic and molecular targets by protons having energies above a few hundred keV, the cross sections for electron production have been found to scale as the number of loosely bound target electrons. The more subtle features of the ejected electron energy spectra are, however, dependent on the electronic structure of the target, especially for emission of low-energy electrons. Although ab initio theoretical techniques are currently limited to simple systems, cross sections for electron production in collisions of bare charged particles with atomic targets can be reliably calculated using Born theory. For more complex targets, models have been developed that provide singly-differential electron-emission cross sections for a wide range of ion energies. These models rely on experimental data to determine parameters that are difficult or infeasible to obtain by ab initio theory. Although great strides have been made in understanding ionization processes involving bare ions and atomic and molecular targets, understanding the collision process for structured ions, i.e., ions that carry bound electrons, as well as collision processes in solid targets, presents a greater challenge. With structured ions, the screening of the ion\u27s nuclear charge by its bound electrons results in an effective interaction potential that depends on the collisional energy loss. In addition, this screened potential has been found to vary with energy loss in a functionally different manner for different light ions. For solid targets, differential ionization cross sections for ion impact are fragmentary, and theoretical results exhibit only qualitative agreement

Differential cross sections for electron emission in heavy ion-atom collisions

The systematics of differential ionization cross sections are explored for incident charged particles which possess atomic structure. Although little has been published regarding outer shell ionization by structured projectiles, sufficient data are becoming available to provide some insight into the collision process. This discussion concentrates on systematics of emission cross sections for the intermediate and high energy projectiles where the applicability of high energy approximations can be tested and the dramatic changes in emission spectra observed as the projectile energies decrease. Since heavy ion interactions are important in many research fields, it is particularly useful to determine where simple methods of cross section scaling may be appropriate

Cross Sections for Ionization of Water Vapor by 7-4000-keV Protons

Cross sections for production of electrons and positive ions by proton impact on water vapor have been measured from 7-4000 keV by the transverse-field method

Cross Sections for Ionization of Water Vapor by 7-4000-keV Protons

Cross sections for production of electrons and positive ions by proton impact on water vapor have been measured from 7-4000 keV by the transverse-field method

Experimental And Theoretical Study Of The Electron Spectra In 66.7350-keV/u C++He Collisions

Measurements of the differential and total cross sections for production of free electrons are reported for collisions of 66.7350-keV/u C+ ions with He. The experimental data are compared with theoretical calculations that include electron emission from both target and projectile using the classical-trajectory Monte Carlo method and the independent-electron approximation. Good agreement is observed between theory and experiment, and structures appearing in the electron spectra can be explained in terms of either, or both, target and projectile ionization. © 1990 The American Physical Society

Electron Emission From Both Target And Projectile In C⁺ + He Collisions

The first classical trajectory Monte Carlo calculation of the electronic spectra arising from both target and projectile ionization is presented and compared with experimental measurements of the differential cross section for electrons emitted in C++He collisions. The theoretical treatment is based on an independent-electron model in which the interactions between the electrons are approximated by quantum model potentials. Good agreement is obtained between theory and experiment and structures appearing in the measurements can be explained in terms of the electron emission from either, or both, target and projectile. Further, the relative importance of the electron capture to the continuum and the electron loss to the continuum peaks is analyzed for different impact energies and the conclusions obtained from this analysis are found to be in agreement with experimental works

Electron Emission from Foils and Biological Materials after Proton Impact

Electron emission spectra from thin metal foils with thin layers of water frozen on them (amorphous solid water) after fast proton impact have been measured and have been simulated in liquid water using the event-by-event track structure code PARTRAC. The electron transport model of PARTRAC has been extended to simulate electron transport down to 1 eV by including low-energy phonon, vibrational and electronic excitations as measured by Michaud et al. (Radiat. Res. 159, 3–22, 2003) for amorphous ice. Simulated liquid water yields follow in general the amorphous solid water measurements at higher energies, but overestimate them significantly at energies below 50 eV. Originally published Radiation Physics and Chemistry, Vol. 77, No. 10-12, Oct-Dec 200