On the angular dependence of L x-ray production cross sections following photoionization at an energy of 59.54 keV

Abstract

The anisotropy of L x-ray fluorescence induced by 59.54 keV unpolarized photons is investigated by means of an experimental procedure which allows the relative L x-ray production cross section to be evaluated without taking account of the angular set-up and the instrumental efficiency. Thick targets of Yb, Hf, Ta, W and Pb are considered, and the angular trend of the relative experimental ratios, I L α /I L β , is calculated by simple evaluations of the peak area alone. Within the experimental uncertainties, which are found to be of the order of 1.6% in the worst cases, the results do not show any significant angular dependence of the L α emission lines if the isotropy of the L β lines is assumed. This fact contrasts with the results of some groups, which report evidence of strong angular dependence at this level of photon energy.

Multiple scattering of photons using the Boltzmann transport equation

“…Rayleigh and Compton scattering are strongly dependent on the polarisation state of the source. In contrast, the transitions filling photoelectric vacancies are almost independent of it [13]. Consequently, multiple scattering comprising different types of collisions will mix the behaviours concerning polarisation of the single participating collisions.…”

Angular Dependence of Fluorescence X-Rays and Alignment of Vacancy State Induced by Radioisotopes

“…The present measurements rule out the possibility of a strong angular dependence of differential cross sections for various L 3 subshell X-rays following selective photoionization of the L 3 subshell. Tartari et al, (2003) investigated the anisotropy of L X-ray fluorescence induced by 59.54 keV unpolarized photons by means of an experimental procedure which allows the relative L X-ray production cross section to be evaluated without taking account of the angular set-up and the instrumental efficiency. Thick targets of Yb, Hf, Ta, W and Pb are considered, and the angular trend of the relative experimental ratios, ⁄ , is calculated by simple evaluations of the peak area alone.…”

X-ray fluorescence activities at Saha Institute of Nuclear Physics, India

“…Data from different groups show contradictory results. The groups at Patiala, India [17][18][19][20] and in Turkey [21][22][23][24][25][26][27][28] got very strong anisotropy while the others [29][30][31][32][33][34][35][36] observed no anisotropy or very little anisotropy in their measurements. Moreover, it is observed that the theoretical value of the alignment parameter based on non-relativistic calculation of Berezhko et al [37] are 2-3 times higher than the experimental values of Küst et al [35], almost five times larger in the case of Papp and Campbell [29] and about half of the experimental values of Yamaoka et al [34].…”