Distorted-wave calculation of cross sections for inner-shell ionization by electronand positron impact

S. SEGUI; M. DINGFELDER; F. SALVAT

PHYSICAL REVIEW A - ATOMIC, MOLECULAR AND OPTICAL PHYSICS

APS

Año: 2003 vol. 67 p. 1 - 12

1050-2947

   The relativistic distorted-wave Born approximation is used to calculate differential and total cross sectionsfor inner shell ionization of neutral atoms by electron and positron impact. The target atom is described withinthe independent-electron approximation using the self-consistent Dirac-Fock-Slater potential. The distortingpotential for the projectile is also set equal to the Dirac-Fock-Slater potential. For electrons, this guaranteesorthogonality of all the orbitals involved and simplifies the calculation of exchange T-matrix elements. Theinteraction between the projectile and the target electrons is assumed to reduce to the instantaneous Coulombinteraction. The adopted numerical algorithm allows the calculation of differential and total cross sections forprojectiles with kinetic energies ranging from the ionization threshold up to about ten times this value. Algo-rithm accuracy and stability are demonstrated by comparing differential cross sections calculated by our codewith the distorting potential set to zero with equivalent results generated by a more robust code that uses theconventional plane-wave Born approximation. Sample calculation results are presented for ionization of K- andL-shells of various elements and compared with the available experimental data.