Analysis of the first Feshbach resonances in electron collisions in rare gases

In this paper we present an analysis of the Feshbach resonances located below the first inelastic threshold in helium, neon, argon, krypton, and xenon. The measurements were made with an electron-scattering spectrometer called MAPDESS capable of simultaneous measurements at up to 19 angles, ranging from 18^∘{} to 162^∘{}. Data are analyzed using single-phase-shift formalism to evaluate the angle-dependent form factors of the resonances, describing the interference of the resonant amplitude with the nonresonant one. For each gas, the use of data at many angles enables a precise evaluation of the first three or four phase shifts and the resonance width. In some cases, the agreement of the analyzed experiment and theory is not perfect at small and large scattering angles.