Excited-State Positronium Formation from Helium, Argon, and Xenon

Excited-state positronium formation from helium, argon, and xenon.

The cross sections for the formation of positronium in the 2P state in collisions of positrons with He, Ar, and Xe atoms have been determined by measuring coincidences between the remnant ion and the Lyman-alpha photon from positronium. The maximum fractional contributions of these to the total Ps formation cross sections increase from approximately 0.06+/-0.01 in He to 0.12+/-0.04 in Ar and 0....

Nuclear-Charge Screening in Positronium Formation from Helium Atoms

An analytical treatment of the electron screening effect within an active-electron model is given for positronium formation from helium atoms. A first-order distorted wave approximation with correct boundary conditions is applied to evaluate the transition amplitude. In the range of impact energy for which the introduced perturbative approach is valid, both the total and differential cross sect...

nuclear-charge screening in positronium formation from helium atoms

an analytical treatment of the electron screening effect within an active-electron model is given for positronium formation from helium atoms. a first-order distorted wave approximation with correct boundary conditions is applied to evaluate the transition amplitude. in the range of impact energy for which the introduced perturbative approach is valid, both the total and differential cross sect...

Beam Induced Fluorescence Monitor - Spectroscopy in Nitrogen, Helium, Argon, Krypton and Xenon Gas

As conventional intercepting diagnostics will not withstand high intensity ion beams, Beam Induced Fluorescence (BIF) profile monitors constitute a preeminent alternative for non-intercepting profile measurements [1]. This diagnostic technique makes use of the optical fluorescence emission of beam-excited gases. Recently BIF became an important diagnostic tool for transversal beam profile measu...

Ground- and excited-state properties of solid argon under pressure