engleski

Estimation of effective charge for subshells of an atom using the impulse approximation for Compton scattering

The impulse approximation (IA) has been applied for the explanation of Compton spectra obtained in photon scattering on bound atomic electrons at higher momentum transfer. Recently made precise measurement of double differential cross section d2sigma/dE/dOmega on absolute scale has shown that an agreement between experimental data and corresponding theoretical values using IA depends on the choice of atomic wave functions. In the present work, we show that IA using the hydrogen-like (HL) wave functions is almost as good as the IA using Hartree-Fock (HF) wave functions if appropriate values of the effective charge are used. These values we have obtained by fitting the double differential cross-section functions obtained by the IA with HL wave functions to the values of double differential cross sections calculated by the IA with HL wave functions, separately for each subshell. In the fitting the effective charges are almost independent on scattering angle and energy of incident photons in cases where the application of the IA is valid. That means that the IA, regarding the effective charge, is very sensitive to the variation of the wave function, where it is not valid. That result indicates the possibility of making a criterion for the validity of the IA within its framework.

Compton spectra; impulse approximation; hydrogen-like wave functions; double differential cross section

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