A study of the collective properties of the degenerate electronic gas in metals using the (e, 2e), (e, 3e), and (γ, 2e) processes at high energies 10³ to 10⁴ eV

The process of quasielastic knock‐out of an electron by the projectile electron (e, 2e) allows one to study the κ‐ and also ε‐dependence of the single‐particle spectral density A (κ, ε). The plasmaronhole excitations of the metal conduction band and the modification of Mahan‐Nozières singularities in the production of a deep hole in a metal are considered as examples. Depending upon the experimental procedure the (e, 3e) and (γ, 2e) processes of knocking out the electron pair provide direct information either about the two‐hole spectral density B (κ 1 , κ 2 , ε) or about the Fourier image fk 1 κ 2 (q) of the electron‐electron correlator f ( r 2 ).