Accurate Compton scattering measurements of noble gases: the importance of electron correlations in heavy atoms

The Compton profiles of He, Ar and Xe atoms are measured using 121.7 keV synchrotron x-rays. Comparisons of the results with recent mean-field Dirac-Hartree-Fock calculations reveal that the degree of discrepancy between the experiment and theory increases as the atomic number increases although the profile of He is reproduced well by the calculation. This study underlines the importance of incorporating the effects of electron correlations into the relativistic calculations.