Statistical modelling by neural networks in gamma-spectrometry

International audienceLayered Neural Networks are a class of models based on neural computation and have been applied to the measurement of uranium enrichment. The usual methods consider a limited number of $X$- and $\gamma$-ray peaks, and require calibrated instrumentation for each sample. Since the source-detector ensemble geometry conditions critically differ between such measurements, the spectral region of interest is normally reduced to improve the accuracy of such conventional methods by focusing on the $K_{\alpha}X$ region where the three elementary components are present. Such measurements lead to the desired ratio. Experimental data have been used to study the performance of neural networks involving a Maximum-Likelihood Method. The encoding of the data by a Neural Network approach is a promising method for the measurement of uranium ${}^{235}U$ and ${}^{238}U$ in infinitely thick samples

Experimental determination of X-ray atomic fundamental parameters of nickel

Abstract X-ray atomic properties of Nickel were investigated in a singular approach that combines different experimental techniques to obtain new and useful reliable values of atomic fundamental parameters for X-ray spectrometric purposes and for comparison to theoretical predictions. We determined the mass attenuation coefficients in an energy range covering the L- and K- absorption edges, the K-shell fluorescence yield and the Kb/Ka and Kb1,3/Ka1,2 transition probability ratios. The obtained line profiles and linewidths of the Ka and Kb transitions in Ni can be considered as the contribution of the satellite lines arising from the [KM] shake processes suggested by Deutsch et al. [1] and Ito et al. [2]. Comparison of the new data with several databases showed a good agreement but also discrepancies were found with existing tabulated values

Application of GUM Supplement 1 to uncertainty of Monte Carlo computed efficiency in gamma-ray spectrometry

Proceedings of the 20th International Conference on Radionuclide Metrology and its Applications (ICRM), 8-11 June 2015, Vienna, Austria. Organizer TU Wien. Editors Franz-Josef Maringer, Dirk Arnold, Uwe Wätjen.International audienceThe uncertainty of quantities relevant in gamma-ray spectrometry (efficiency, transfer factor, self-attenuation FA and coincidence summing FC correction factors) is realistically evaluated by Monte Carlo propagation of the distributions characterizing the parameters on which these quantities depend. Probability density functions are constructed and summarized as recommended in the GUM Supplement 1 and compared with the values obtained using the traditional approach (GUM uncertainty framework). Special. cases when this approach encounters difficulties (FC uncertainty due to the uncertainty of decay scheme parameters, effect of activity and matrix inhomogeneity on efficiency) are also discussed

Editorial summary of the EXRS 2006 conference

The 12th European X-ray Spectrometry Conference was held between June 19 and 23, 2006, in Paris, France. The organizers were the Laboratoire National Henri Becquerel, CEA, and the Ecole Normale Sup ´ erieure de Lyon, CNRS. The venue of the conference was the Cite Internationale Universitaire, the famous complex of the Universite de Paris built between the two World Wars as an international meeting ground for knowledge and peace. The 35-ha park surrounding the Maison Internationale, which hosted the meeting, is a place for students from over 125 nations to get together, and is spread out among 37 turn-of-the-century residences

Reference-free combined XRR-GIXRF analysis at the French Synchrotron SOLEIL

International audienceChambre d'Analyse Spectrométrique en Transmission ou en Réflexion (Analysis Chamber for Transmission or Reflection Spectrometry) (CASTOR) is a new instrument, operated at the SOLEIL synchrotron facility, dedicated to the metrological characterization of thin films with thicknesses in the nanometer range. The instrument can combine two X-ray techniques, namely, the reflectivity (XRR) measurements with fluorescence (XRF) acquisitions and especially total-reflection X-ray fluorescence (TXRF)-related techniques such as grazing-incidence XRF (GIXRF). The instrument is most often installed on the hard X-ray branch of the Metrology beamline. Geometrical characterization is presented, reproducibility of measurements is studied, and the reference-free GIXRF analysis is described. Some representative examples are given to illustrate the capabilities of the setup and the combined analysis procedure

International Initiative on X-ray Fundamental Parameters status and next steps

International audienceAccurate critical data related to the interactions of X-rays with matter, called Fundamental Parameters (FP), are of paramount importance in many branches of physics and technology. However, the lack of recent reliable values of fundamental parameters with low associated uncertainties, and in addition a high degree of consistency over wider atomic number ranges, is regularly pointed out by end users of X-ray instrumentation e.g., with respect to industrial needs. In order to meet current and upcoming demands, the International Initiative on X-ray Fundamental Parameters (IIFP) started as an expression of common interest in the improvement of X-ray fundamental parameters in a joint effort of companies, university laboratories, and national metrology institutes [1]. This stimulates:(i) experimental measurements based on new facilities such as synchrotron radiation and high-resolution detectors with reduced and traceable uncertainties; comparison between different experimental approaches [2] validates the derived FPs;(ii) theoretical calculations using the most recent theoretical approaches; the MultiConfiguration Dirac-Fock (MCDF) enables the determination of many of the significant atomic parameters due to the possibility of including, a large amount of electronic correlation and radiative corrections. The comparison of experimental and theoretical results on selected elements [3] assesses the validity of calculation that should be used when experimental approaches are difficult or impossible;(iii) preparation of a standardized FP database established through a co-work of national metrology institutes providing user access to reliable data

Reconstruction problem by maximum entropy method applied on a mixture of experts

Layered Neural Networks, which are a class of models based on neural computation, are applied to the measurement of uranium enrichment. The usual methods consider a limited number of γ-ray and X-ray peaks, and require previously calibrated instrumentation for each sample. But since, in practice, the source-detector ensemble geometry conditions are critically different, a mean of improving the above conventional methods is to reduce the region of interest ; this is possible by focusing on the KαX region where the three elementary components are present. The measurement of these components in mixtures leads to the desired ratio. Real data are used to study the performance of neural networks and training is done with a Maximum Likelihood Method. We show that the encoding of data by Neural Networks is a promising method to measure uranium 235U and 238U quantities in infinitely thick samples

Photon emission intensities in the decay of U-235

Proceedings of the 7th International Conference on Radionuclide Metrology - Low Level Radioactivity Measurement Techniques (ICRM-LLRMT), Seattle, USA, SEP 26-30, 2016International audienceNew measurements of photon emission intensities in the decay of U-235 were performed. Source was prepared by deposition of a U-235 solution on glass plate. Standardization was carried out by defined solid angle alpha counting, giving the reference activity with 0.7% relative combined uncertainty. Gamma spectrometry was performed with accurately calibrated high-purity germanium detectors. Corrections for source geometry and coincidence summing effects were applied. The reference line (185.72 keV) intensity was obtained with 1.3% relative standard uncertainty

Determination of absolute photon emission intensities of 210 Pb

Proceedings of the 20th International Conference on Radionuclide Metrology and its Applications (ICRM), 8-11 June 2015, Vienna, Austria. Organizer TU Wien. Editors Franz-Josef Maringer, Dirk Arnold, Uwe Wätjen.International audiencePhoton emission intensities of Pb-210 have been determined using sources prepared from a standard solution, whose activity was measured by liquid scintillation counting. The absolute gamma-ray and X-ray emission intensity was measured by conventional gamma-ray spectrometry. Complementary measurements of the L X-ray spectrum were performed using a cryogenic detector, characterized by very high energy resolution and constant detection efficiency. As a result, precise emission intensities of the individual X-ray lines were obtained taking into account the presence of satellite lines

Atomic and nuclear decay data evaluations at the French national metrology laboratory for ionising radiation

International audienceAs part of the activity related to atomic and nuclear decay data evaluations, the French national metrology laboratory for ionising radiation, the Laboratoire National Henri Becquerel (LNE-LNHB), coordinates the Decay Data Evaluation Project (DDEP). The DDEP is an international collaboration providing easy-to-use and reliable decay data recommendations. It was originally founded in 1994 between two National Metrology Institutes (NMIs) for ionising radiation: the LNE-LNHB, France, and the Physikalisch-Technische Bundesanstalt (PTB) in Germany. The collaboration was later strengthened through the addition of laboratories from the US, China, Romania, Russia, Spain and the UK. Beyond the initial scope of ionising radiation metrology, the DDEP recommendations are used for a wide variety of topics, from fundamental physics to nuclear medicine applications. Most notably, almost all 220 DDEP evaluations are included in the latest version of the radioactive decay data library from the Joint Evaluated Fission and Fusion (JEFF) file project of the OECD Nuclear Energy Agency.This communication aims to present an overview of the evaluation project. The guidelines of the collaboration as well as the evaluation pipeline will be presented. The various dissemination media used by the collaboration will be detailed and the recent update of the website will be highlighted. The future improvements of the database will be discussed