Éditeur(s) : HAL CCSD American Chemical Society
Résumé : Absolute Mα and Mβ X-ray intensities were measured for the elements Pt, Au, Pb, U, and Th by electron impact for energies ranging from 6 to 38 keV. Experimental data were obtained by measuring the X-ray intensity emitted from bulk samples with an electron microprobe using high-resolution wavelength-dispersive spectrometers. Recorded X-ray intensities were converted into absolute X-ray yields by evaluation of the detector efficiency and then compared with X-ray intensities calculated by means of Monte Carlo simulations. Simulated Mα and Mβ X-ray intensities were found to be in good agreement with the measurements, allowing their use in standardless quantification methods. A procedure and a software program were developed to accurately obtain virtual standard values. Standardless quantifications of Pb and U were tested on standards of PbS, PbTe, PbCl2, vanadinite, and UO2.
ISSN: 0003-2700

hal-01217495
https://hal.archives-ouvertes.fr/hal-01217495
DOI : 10.1021/acs.analchem.5b01443

Éditeur(s) : HAL CCSD Institute of Electrical and Electronics Engineers (IEEE) Institute of Electrical and Electronics Engineers
Résumé : International audience
Conventional quantitative electron probe microanalysis of actinides requires the use of reference standard samples. However, for such elements, standards are generally not available. To overcome this difficulty, standardless methods of analysis are used, in which the x-ray intensity emitted by the standard is calculated. To be reliable, such calculations require accurate knowledge of physical data such as the x-ray production cross section. However, experimental data of this quantity are not always available for actinide elements. In the present work, experimental L and M x-ray production cross sections were measured for elements uranium and lead. Measurements were performed with two electron microprobes using wavelength-dispersive spectrometers using thin self-supporting targets. Experimental results are compared with calculated cross sections obtained from different analytical formulae, and, whenever possible, with experimental data obtained from the literature.
ISSN: 0018-9499

hal-01122820
https://hal.archives-ouvertes.fr/hal-01122820
DOI : 10.1109/TNS.2014.2321016

Éditeur(s) : HAL CCSD Wiley-Blackwell
Résumé : International audience
Absolute Mα x-ray production cross sections have been measured and calculated for heavy elements Au, Pb, Bi, and U for electron incident energies from the ionization threshold up to 38 keV. The experimental cross sections were deduced from M x-ray intensities emitted from ultrathin samples of the elements of interest deposited onto self-supporting C films. The measurements were performed using two electron microprobes and several wavelength-dispersive spectrometers. X-ray intensities were converted into x-ray production cross sections by using estimated values of the number of incident electrons, target thickness, and spectrometer efficiency. Experimental results are compared with calculated cross sections using different predictive formulae. Good agreement is found between the measured cross sections and the predictions from the distorted-wave Born approximation, which indicates that this approximation is suited for the calculation of M-shell ionization cross sections of heavy elements.
ISSN: 0142-2421

hal-01122839
https://hal.archives-ouvertes.fr/hal-01122839
DOI : 10.1002/sia.5561

Éditeur(s) : HAL CCSD IOP Publishing
Résumé : International audience
M-subshell ionization cross sections of U by electron impact with kinetic energies between 4 and 38 keV were determined experimentally. The cross sections have been deduced from high-resolution measurements of the M x-ray emission spectra resulting from the radiative decay of M-subshell vacancies. The experimental cross sections are compared with cross sections calculated within the plane- and distorted-wave Born approximations. The predictions of the distorted-wave Born approximation represent experimental measurements well within experimental errors.
ISSN: 0953-4075

hal-01054329
https://hal.archives-ouvertes.fr/hal-01054329
DOI : 10.1088/0953-4075/47/5/055202

Éditeur(s) : HAL CCSD EDP Sciences
Résumé : We propose and we justify a Monte-Carlo algorithm which solves a spatially homogeneous kinetic equation of Boltzmann type that models the fusion reaction between a deuterium ion and a tritium ion, and giving an α particle and a neutron. The proposed algorithm is validated with the use of explicit solutions of the kinetic model obtained by replacing the fusion cross-section by a Maxwellian cross section.
ISSN: 1270-900X

hal-00689821
https://hal.archives-ouvertes.fr/hal-00689821
https://hal.archives-ouvertes.fr/hal-00689821/document
https://hal.archives-ouvertes.fr/hal-00689821/file/proc_versionHAL.pdf

Éditeur(s) : HAL CCSD IOP Publishing
Résumé : Absolute L- and M-subshell x-ray production cross sections of Pb have been measured for incident electron energies ranging from 3 to 38 keV. The experimental cross sections were obtained by measuring Lα, Lβ, Mα, Mβ and Mγ x-ray intensities emitted from ultrathin Pb films deposited onto self-supporting thin C films. Measurements were performed on two electron microprobes using wavelength-dispersive spectrometers. X-ray intensities were converted into x-ray production cross sections by using estimated values of the number of incident electrons, target thickness and spectrometer efficiency. Experimental results are compared with calculated cross sections obtained using different predictive formulae, and, whenever possible, with experimental data from the literature.
ISSN: 0953-4075

hal-00858079
https://hal.archives-ouvertes.fr/hal-00858079
DOI : 10.1088/0953-4075/46/11/115202