Angular distributions of differential X-ray production cross sections for Cu and Ta in photoionization

The characteristic K-shell X-ray emission of Cu and L X-rays of Ta in photoionization has been measured at excitation energy of 15.9keV. The differential X-ray production cross sections of K_α and K_β for Cu and L_α, L_β1, L_β2, L_γ1 for Ta are derived at emission angles ranging from 100° to 150°. The ratio of K_β and K_α X-ray production cross sections, K_β/K_α, is calculated for Cu and it is found to be consistent with other work even at different incident energy. While the ratios of L_α/L_β, L_α/L_γ1 and L_β/L_γ1 for Ta are found to be different with other results at different excitation energy. The reasons giving rise to this discrepancy are clarified with thorough analysis.