Angular Distribution of Xe5s→εpPhotoelectrons: Disagreement between Experiment and Theory

The angular asymmetry parameter $\beta$ for the Xe $5s\to \epsilon p$ photoelectrons has been studied with use of synchrotron radiation ($h\nu =28-65\mathrm{}$ eV). The present results show that the relativistic random-phase approximation theory does not satisfactorily describe the Xe $5s$ photoionization process close to the Cooper minimum and thus require a renewed theoretical approach. The $5s$ partial photoionization cross section was obtained over the same photon region and the results agree with experimental values found in the literature.