Measurement of photon-induced L3 subshell to M shell vacancy transfer probabilities and angular distribution of fluorescence x-rays and determination of anisotropy parameters

ABSTRACT Ph. D. Thesis MEASUREMENT OF PHOTON-INDUCED L3 SUBSHELL TO M SHELL VACANCY TRANSFER PROBABILITIES AND ANGULAR DISTRIBUTION OF FLUORESCENCE X-RAYS AND DETERMINATION OF ANISOTROPY PARAMETERS Yüksel ÖZDEMİR Atatürk University Faculty of Arts and Sciences Department of Physics Supervisor: Assoc. Prof. Dr. Rıdvan DURAK The differential cross-sections for the emission of M-shell fluorescence X-rays for elements atomic range 71^ Z <, 92 using 5.96 keV photons have been measured at seven angles ranging from 120° to 150°. It is found that differential cross-sections in decrease with increase in the emission angle showing anisotropic spatial distribution of M-shell fluorescence X-rays. The obtained results have been compared with the theoretical values. At second section of our work, the differential cross-sections for the emission of M and L shell fluorescence X-rays for elements atomic range 71 < Z < 92 have been measured using K X-rays of Zn, Ga, Ge, As, Se, Br, Rb,, Nb, and Mo respectively at the same angles ranging and same geometry. Energies of K. X-ray are above the L3 edge but below L2 edge energies of the respective target elements under reference, therefore the M X-rays are produced not only due to direct interaction of incident photons with M shell electrons but also due to the decay of L3 subshcll vacancies to M shell. At third section of our study, in order to obtain the experimental angular distributions of L3 subshcll vacancies to M shell from the measured angular distribution of M shell fluorescence X-ray differential cross-sections obtained first section and second section at the same geometry of our work have been used. Angular distributions of vacancy transfer probabilities from L3 subshell to M shell have been also obtained for the elements The obtained results have been compared with the theoretical values. Li anizotropy parameter and the lineer polarization degree of LI, La, L/3, and Ly X- rays of some elements in the atomic range 65 < Z < 92 have been measured. Because the polarization degrees of characteristic L X-rays is not found in the literature the comparison has been not made with experimental and theoretical results. 2002, 145 pages Keyword: X-ray fluorescence, vacancy transfer probability, cross-sections, photoionization, X-ray polarization. 11