Impact-Parameter Dependence of Vacancy Production in Strongly Bound Quasimolecular States of Heavy Collision Systems

Abstract

With a new method to determine the impact-parameter dependence, $P(\ensuremath{\rho})$, of $K$-shell vacancy production, which utilizes a kinematic analysis of Doppler-broadened x-ray lines, we show that the $K$-shell excitation probability in heavy collision systems at Coulomb barrier energies is both large and narrowly peaked at small impact parameters. In particular, for $1s\ensuremath{\sigma}$ excitations, $P(\ensuremath{\rho}\ensuremath{\simeq}0)$ can exceed a few percent with approximately half the total cross section contributed by collisions with $\ensuremath{\rho}\ensuremath{\lesssim}40$ fm.