MEASUREMENT OF ANGULAR-DISTRIBUTION AND POLARIZATION OF PHOTON-INDUCED FLUORESCENT X-RAYS IN THORIUM AND URANIUM

The angular distribution and polarization of the L-shell fluorescent x rays excited by 59.57-keV photons in Th and U have been measured. It is found that the L-gamma group of L x rays is isotropic in spatial distribution and unpolarized but, the Ll and L-alpha groups are anisotropically distributed and are polarized. Although no anisotropy of the L-beta group is detected, it is found to be slightly polarized. The present results contradict the predictions of the calculations of Cooper and Zare [Atomic Collision Processes (Gordon and Breach, New York, 1969)] that after photoionization the magnetic substates of all subshell vacancy states are equally populated. However, the present results confirm the predictions of Flugge, Mehlhorn, and Schmidt [Phys. Rev. Lett. 29, 7 (1972)] that the population distribution of the magnetic substates of all subshell vacancy states with J > 1/2 is nonstatistical.