We discuss some experimental facets of electron pair emission from surfaces using two different approaches. In the first case instrument consists a hemispherical analyzers which are operated with continuous primary beams electrons or photons. The second employs time-of-flight spectrometers require pulsed excitation source. A key quantity is ratio ‘true’ to ‘random’ coincidences can be determine...

Abstract The electric field surrounding a single positron in metal is screened by an increase the local electron density which, case of nearly free-electron metals (like Al, Na, etc.), has radial distribution similar to that positronium (Ps). In such metals, singlet pair positrons would experience attractive interaction and at low enough densities could possibly form bound state held together e...

In photon-atom scattering the customary partitioning of the elastic scattering amplitude into Rayleigh and Delbr uck amplitudes (as well as nuclear amplitudes) in the single-electron formalism involves summations over complete sets of intermediate electron states in the atomic potential. This leads to the Rayleigh amplitude which is usually compared with experiment. However another consequence ...

We study Schwinger pair creation of charged particles due to the inhomogeneous electric field created by the thin electron layer at the surface of quark stars (the electrosphere). As suggested earlier, due to the low photon emissivity of the quark-gluon plasma and of the electrosphere, electron-positron pair emission could be the main observational signature of quark stars. To obtain the electr...