Electron, Positron and Photon Collisions with Atoms and Molecules

Heavy Particle Collisions

Extensive calculations have been performed for single ionization of neutral target atoms by highly charged ion-impact at KeV to MeV collision energies using the continuum distorted wave eikonal-initial state (CDW-EIS) and continuum distorted wave (CDW) approximations. The calculations are of relevance to experiments in recoil-ion spectroscopy and ejected electron spectroscopy which allow one to measure the vector momenta of several ions and electrons resulting from atomic fragmentation. These calculations provide detailed knowledge about the properties and behaviour of highly charged ions which is crucial for other areas including astro- and solar physics. Additionally computer codes have also been developed and published in Computer Physics Communications for calculation of ionization cross sections by fast ion impact for neutral target atoms ranging from hydrogen to neon are available world wide.

Calculations involving charge transfer processes which are of interest to physicists studying a wide range of phenomena in astrophysics have also been considered using the CDW approximation. Data arising from these calculations have been extensively published in articles in IOP Science and Physical Review journals. 

Coincidence studies

Coincidence studies provide valuable insights into ionization dynamics, helping to elucidate ionization mechanisms. A coincidence measurement involves the determination of the momentum and charge state of the ingoing and exiting projectile as well as the momentum of the ionized electron(s). In CTAMOP there is considerable expertise in the theoretical study of coincidence processes, ranging from very low energies up to the relativistic domain, and from single ionization processes to double excitation processes such as ionization with excitation and transfer ionization.

Recent work has focused upon ionization with antiprotons, protons, C6+, C6-, Au24+, Au53+, and O8+, and with targets of H(1s), He(1s2), Li(2s) and Li(2p) (McGovern et al, Phys Rev A 79, 042707 (2009); 81, 032708 (2010); 81, 042704 (2010); 82, 032702 (2010); Walters and Whelan, Phys Rev A 85, 062701 (2012)).

A powerful armoury of interlocking techniques has been developed, ranging from perturbation theory, both non-relativistic and relativistic, to highly sophisticated large scale coupled pseudostate methods.