The ionization of atoms, ions and molecules by electron impact are basic processes of atomic and molecular physics, with fundamental applications in different areas as astrophysics, condensed matter physics, plasma physics, fusion physics, surface science etc. Electron coincidence experiments in which an incoming electron knocks out a bound electron in a collision with target and the two outgoing electrons are then detected in coincidence with defined kinematics are known as (e, 2e) experiments. Such types of investigations have been done to study the momentum distribution of valence electrons in atoms and molecules [1]. Recently, Purohit et al [2], Sud and Purohit [3] and Sud et al [4] have theoretically demonstrated up-down asymmetry and dichroism effects in the relativistic (e, 2e) processes for the K-shell ionization of atoms respectively. They have demonstrated that up-down asymmetry and dichroism effect depends on the interference between the transition charge and component of the transition current perpendicular to the scattering plane. We present in this communication the results of our calculation of right-left asymmetry in the relativistic (e, 2e) processes for inner K-shell ionization of atoms. The calculation has been performed in plane wave Born approximation (PWBA) using one photon exchange approximation. In our model the incident and scattered electrons are described by Dirac plane waves, bound electron by Darwin wave function in Coulomb potential and ejected electron by non relativistic Coulomb wave function multiplied by Darwin matrix. The triple differential cross section (TDCS), in plane wave Born approximation (PWBA) can be factorized into products of electron kinematic factors and atomic structure functions [5]. The right left asymmetry in the relativistic (e, 2e) process on the K-shell of the atoms has been shown to depend on the interference between the transition charge and component of the transition current in the scattering plane. Further, we will discuss the dependence of right-left asymmetry on the incident electron energy, atomic number of the target and scattering angles.

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