Photon-induced L X-ray production differential cross sections in thorium at 22.6 keV

The L1, L alpha, L beta(2,4), L beta(1,3) and L gamma(1,5) X-ray production differential cross sections in Th-90 have been measured at 22.6 keV incide nt photon energy in an angular range 50-130 degrees. The measurements were performed using a Cd-109 annular-source and a Si(Li) detector. The measured differential cross sections for various L X-rays are found to be angle-ind ependent within experimental error. This is contrary to the strong angular- dependence of photon-induced L1 and La X-ray production cross sections as r eported by Kahlon et al, (K.S. Kahlon, H.S. Aulakh, N. Singh, R. Mittal, K. L. Allawadhi, B.S. Sood, Phys. Rev. A 43 (1991) 1455) and Ertugrul (M. Ert ugrul, Nucl. Instr. and Meth. B 119 (1996) 345). Integral cross sections fo r production of L1, L alpha, L eta, L beta(6), L beta(2,4), L beta(1,3), L beta(9,10), L gamma(1,5) and total L gamma X-rays are also deduced and are found to be in good agreement with those calculated using reliable theoreti cal values of the Li (i=1, 2, 3) subshell photoionisation cross sections, f luorescence yields, X-ray emission rates and Coster-Kronig transition proba bilities. (C) 1999 Published by Elsevier Science B.V. All rights reserved.