Ionization of Helium and Argon by Very Slow Antiproton Impact

The total cross sections for single ionization of helium and single and double ionization of argon by antiproton impact have been measured in the kinetic energy range from 3 to 25 jeVusing a new technique for the creation of intense slow antiproton beams. The new data provide benchmark results for the development of advanced descriptions of atomic collisions and we show that they can be used to judge, for the first time, the validity of many recent theories.

Evidence for rescattering in molecular dissociation

Dissociation of the singly ionized CO2+ ion has been investigated in an intense ultrafast (55 fs) laser field, by employing an intensity selective scan technique and comparing the signals from linearly and circularly polarized pulses. Non-sequential contributions have been observed unambiguously for the first time, highlighting the role of rescattering in the dissociative process.

2-D R-matrix Propagator: Application and Future Developments

Ongoing developments of the 2-D R-matrix propagator are discussed. These include application to electron and photon collisions with H-like ions; computational innovations; and important theoretical developments to enable the accurate treatment of electron and photon collisions with multi-electron atoms at intermediate energies.

Electron-impact excitation of the astrophysically important singly ionized Fe-peak ions Sc and Ti

In this work we report on the evaluation of electron-impact collision strengths and Maxwellian averaged effective collision strengths for the lowly-ionized Fe-peak elements Sc II and Ti II using the parallel R-matrix package RMATRX II.

Electron-Impact Excitation of Fe-peak Ions for Astrophysical Applications

This paper discusses one of the major outstanding problems in atomic collision physics, namely the accurate theoretical treatment of electron scattering from open d-shell systems, and explores how this issue has been addressed over recent years with the development of the new parallel R-matrix suite of codes. It focuses on one code in particular - the new parallel R-matrix package PRMAT, which has recently been extended to account for relativistic fine-structure effects. This program facilitates the determination of accurate electron-impact excitation rates for complex open 3d-shell systems including the astrophysically important Fe-peak ions such as Ni II, Fe II and Fe III. Results are presented for collision strengths and Maxwellian averaged effective collision strengths for the optically forbidden fine-structure transitions of Ni II. To our knowledge this is the most extensive calculation completed to date for this ion.