ELECTRON-CAPTURE FROM LITHIUM AND ITS IONS BY HIGH-ENERGY PROTONS

The continuum-distorted wave method is used to calculate cross sections for electron capture by fast protons from the lithium atom and its related positive ions. With the exception of Li2+(12S), each target electronic state is described by a Hartree-Fock wavefunction. For the lithium atom, capture can occur from either the K or L shell and the resulting ion can exist either in its ground state 11S or in one of the excited states 21S or 23S; cross sections are tabulated for each of these states for capture into the hydrogen levels (nl). Results for the individual capture states (nl) are also reported for the Li+ target. Total capture cross sections are calculated for each target by means of the Oppenheimer n-3 rule. For Li and Li+, total cross sections are also evaluated at E<200 keV. A procedure for determining the effective screening of the target nucleus by the uncaptured electrons is discussed and the sensitivity of the cross sections with respect to such screening is examined.