Measurement of the atomic alignment by electron impact from L x-rays angular distribution

• Grant number: 13/24803-5
• Support type: Scholarships in Brazil - Doctorate
• Effective date (Start): April 01, 2014
• Effective date (End): October 08, 2017
• Field of knowledge: Physical Sciences and Mathematics - Physics - Atomic and Molecular Physics
• Principal researcher: Vito Roberto Vanin
• Grantee: Suelen Fernandes de Barros
• Home Institution: Instituto de Física (IF). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

We propose to measure the angular distribution of L x rays obtained by impact of electrons with energies of 10 to 100 keV, produced by the injector of the Microtron accelerator in elements of varied atomic number. If this distribution is found to be anisotropic, we will determine the degree of alignment of ions with a precision of about 10%. We plan to perform measurements for targets with varying thicknesses, in order to understand better the competing processes that affect the measurements. Some theories predict alignment when the total angular momentum J of the vacancy is larger than 1/2 while others conclude that the angular distribution is isotropic, regardless of the J value. The experimental data found in the literature refer mostly to the alignment by impact of protons or photoionization, are scarce and discrepant: while some authors found a strong anisotropy in the angular distribution parameter and high alignment, others observed an isotropic angular distribution. Although the alignment and orientation of atomic shells in the excitation of outer-shell electrons by electron impact is a well-studied and well-known phenomenon, the alignment by ionization has not yet been conclusively observed. A quantitative explanation of this phenomenon, or its absence, and the resulting angular distribution of the emission of x rays constitute a particularly sensitive test of the atomic structure model.

Scientific publications

(4)

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

BARROS, SUELEN F.; VANIN, VITO R.; MANGIAROTTI, ALESSIO; MAIDANA, NORA L.; FERNANDEZ-VAREA, JOSE M. Atomic alignment of Ta-73, W-74, and Au-79 after L-3 subshell ionization by 10-100-keV electron impact. Physical Review A, v. 100, n. 6 DEC 10 2019. Web of Science Citations: 0.

VANIN, VITO R.; MAIDANA, NORA L.; MANGIAROTTI, ALESSIO; LIMA, ROBERTO R.; MALAFRONTE, ALEXANDRE A.; BARROS, SUELEN F.; MARTINS, MARCOS N. The 10-100 keV beam line of the Sao Paulo Microtron electron accelerator. Radiation Physics and Chemistry, v. 154, n. SI, p. 26-31, JAN 2019. Web of Science Citations: 3.

BARROS, SUELEN F.; VANIN, VITO R.; MALAFRONTE, ALEXANDRE A.; MAIDANA, NORA L.; MARTINS, MARCOS N. Energy-dependent dead-time correction in digital pulse processors applied to silicon drift detector's X-ray spectra. JOURNAL OF SYNCHROTRON RADIATION, v. 25, n. 2, p. 484-495, MAR 2018. Web of Science Citations: 1.

BARROS, SUELEN F.; VANIN, VITO R.; MAIDANA, NORA L.; MARTINS, MARCOS N.; GARCIA-ALVAREZ, JUAN A.; SANTOS, OSVALDO C. B.; RODRIGUES, CLEBER L.; KOSKINAS, MARINA F.; FERNANDEZ-VAREA, JOSE M. Ionization cross sections of the Au L subshells by electron impact from the L-3 threshold to 100 keV. JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS, v. 51, n. 2 JAN 28 2018. Web of Science Citations: 3.