14 results on '"Julien-Laferrière Sylvain"'
Search Results
2. From fission yield measurements to evaluation: status on statistical methodology for the covariance question
- Author
-
Voirin Brieuc, Kessedjian Grégoire, Chebboubi Abdelaziz, Julien-Laferrière Sylvain, and Serot Olivier
- Subjects
Nuclear engineering. Atomic power ,TK9001-9401 - Abstract
Studies on fission yields have a major impact on the characterization and the understanding of the fission process and are mandatory for reactor applications. Fission yield evaluation represents the synthesis of experimental and theoretical knowledge to perform the best estimation of mass, isotopic and isomeric yields. Today, the output of fission yield evaluation is available as a function of isotopic yields. Without the explicitness of evaluation covariance data, mass yield uncertainties are greater than those of isotopic yields. This is in contradiction with experimental knowledge where the abundance of mass yield measurements is dominant. These last years, different covariance matrices have been suggested but the experimental part of those are neglected. The collaboration between the LPSC Grenoble and the CEA Cadarache starts a new program in the field of the evaluation of fission products in addition to the current experimental program at Institut Laue-Langevin. The goal is to define a new methodology of evaluation based on statistical tests to define the different experimental sets in agreement, giving different solutions for different analysis choices. This study deals with the thermal neutron induced fission of 235U. The mix of data is non-unique and this topic will be discussed using the Shannon entropy criterion in the framework of the statistical methodology proposed.
- Published
- 2018
- Full Text
- View/download PDF
3. New measurements on isobaric fission product yields and mean kinetic energy for 241Pu thermal neutron-induced fission
- Author
-
Julien-Laferrière Sylvain, Kessedjian Grégoire, Serot Olivier, Chebboubi Abdelaziz, Bernard David, Blanc Aurélien, Köster Ulli, Litaize Olivier, Materna Thomas, Meplan Olivier, Rapala Michal, and Sage Christophe
- Subjects
Physics ,QC1-999 - Abstract
Nuclear fission yields data measurements for thermal neutron induced fission of 241Pu have been carried out at the Institut Laue Langevin (ILL) in Grenoble, using the Lohengrin mass spectrometer. Mass, isotopic and isomeric yields have been extracted for the last measurements. A focus is given in this document to the mass yield results which are obtained for almost the entire heavy peak and most of the light high yields masses, along with the covariance matrix. The mean kinetic energy as a function of the fission product mass has also been extracted from the measurements. The total mean kinetic energy pre and post neutron emission have been assessed and compared to other works showing a rather good agreement.
- Published
- 2018
- Full Text
- View/download PDF
4. Theoretical investigation of fission fragment kinetic energy distributions in the symmetric mass region for 233U(nth,f)
- Author
-
Chebboubi Abdelaziz, Serot Olivier, Kessedjian Grégoire, Litaize Olivier, Blanc Aurelien, Bernard David, Faust Herbert, Julien-Laferrière Sylvain, Köster Ulli, Letourneau Alain, Materna Thomas, Méplan Olivier, Mutti Paolo, Rapala Michal, and Sage Christophe
- Subjects
Physics ,QC1-999 - Abstract
Fission yields are essential for nuclear reactor studies (decay heat, fuel inventory…) and constitute also one of the main observables needed to improve our understanding of the fission process. The symmetric mass region is of particular interest due to various intriguing properties of the fission fragments already reported in the literature : inversion of the nuclear charge polarization, large width of the fission fragment kinetic energy distribution, strong change of the prompt neutron multiplicity, etc. Recently, measurements of fission yields and kinetic energy distributions in the symmetric mass region were achieved at the LOHENGRIN mass spectrometer of the Institut Laue-Langevin (ILL). This experimental work is challenging due to the low counting rate and the appearance of contaminant masses, leading to pronounced components in the fission fragment kinetic energy distribution. Despite removing the undesirable contributions, the fission fragment kinetic energy distributions still show two components, indicating that the fission process could be modal. To go further and better characterize these components a comparison between our experimental data and Monte Carlo calculations (FIFRELIN code) simulating the de-excitation of the fission fragments for different fission channels will be presented and discussed.
- Published
- 2017
- Full Text
- View/download PDF
5. Near Real-Time Earthquake Line-Source Models Derived from Felt Reports
- Author
-
Bose Maren, Julien-Laferrière Sylvain, Bossu Rémy, and Massin Frédérik
- Subjects
Earthquake ,Felt Reports - Abstract
Rapid information on fault rupture geometry is critically important to assess damage and fatalities in large earthquakes and is strongly needed to coordinate rapid rescue efforts if and where necessary. Many countries around the world, however, cannot afford to operate dense seismic networks required to rapidly determine rupture geometry. In this feasibility study, we investigate if crowd-sourced felt intensity reports can be used to close this information gap and enable determination of the orientation and spatial extent of fault ruptures. We apply the Finite-Fault Rupture Detector (FinDer) algorithm to felt intensity reports collected by the European-Mediterranean Seismological Centre (EMSC). We develop an empirical relationship between the azimuthal gap between felt reports and FinDer performance for automated event selection. This gives us a dataset of 36 global earthquakes (6:0≤M≤7:3) between 2014 and 2020. We find that the resulting FinDer line-source models are generally consistent with the spatially dependent intensity patterns described by the felt reports, and in many earthquakes achieve a good agreement with the finite-source models published in the literature: for 50% of events the difference in strike is less than 30°, and for 75% less than 55°. FinDer line-source models could be calculated automatically for global earthquakes (M≥6) within 10–30 min after their occurrence, provided a sufficient number of felt reports were available. However, our proposed method not only provides faster results, but also helps to fill a general information gap for many earthquakes around the world, for which rupture geometry information is currently unavailable.
- Published
- 2021
- Full Text
- View/download PDF
6. Near Real-Time Earthquake Line-Source Models Derived from Felt Reports
- Author
-
Böse, Maren, primary, Julien-Laferrière, Sylvain, additional, Bossu, Rémy, additional, and Massin, Frédérick, additional
- Published
- 2021
- Full Text
- View/download PDF
7. Citizen Seismology Without Seismologists? Lessons Learned From Mayotte Leading to Improved Collaboration
- Author
-
Fallou, Laure, primary, Bossu, Rémy, additional, Landès, Matthieu, additional, Roch, Julien, additional, Roussel, Frédéric, additional, Steed, Robert, additional, and Julien-Laferrière, Sylvain, additional
- Published
- 2020
- Full Text
- View/download PDF
8. Rapid Public Information and Situational Awareness After the November 26, 2019, Albania Earthquake: Lessons Learned From the LastQuake System
- Author
-
Bossu, Rémy, primary, Fallou, Laure, additional, Landès, Matthieu, additional, Roussel, Fréderic, additional, Julien-Laferrière, Sylvain, additional, Roch, Julien, additional, and Steed, Robert, additional
- Published
- 2020
- Full Text
- View/download PDF
9. Approche expérimentale et phénoménologique des rendements de la fission induite par neutron thermique du 239Pu et du 241Pu
- Author
-
Julien-Laferrière, Sylvain, Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS), Université Grenoble Alpes, Grégoire Kessedjian, and Olivier Sérot
- Subjects
Lohengrin ,Fifrelin ,Fission yield ,[PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex] ,Rendement de fission ,Plutonium - Abstract
Nuclear fission, although known for 80 years, remains a theoretical challenge. The complexity and multiplicity of interactions within a splitting nucleus make the modelling of the fission phenomenon delicate. Nuclear fission models struggle to replicate observables. Among these observables, however, fission yields are key ingredients for reactor physics. If they cannot be predicted effectively, it is necessary to measure them.The evaluated nuclear data libraries, which condense the current knowledge of these fission yields, nevertheless present significant uncertainties, as well as discrepancies.For several years, a collaboration between the CEA, the CNRS and the Laue Langevin Institute (ILL) has aimed at accurately measuring the yields of thermal neutron induced fission for actinides of importance for the Uranium-Plutonium and Thorium-Uranium cycles, in order to complete current knowledge and also provide reference data for model testing.In particular, during this thesis, experimental data acquired on the LOHENGRIN mass spectrometer at the ILL in Grenoble (France) were analysed for 239Pu(nth,f) and 241Pu(nth,f). Two types of yields were determined: mass yields, using an ionization chamber, and isotopic yields, by spectrometry γ with Ge.Thanks to a rigorous experimental protocol testing the reproducibility of the observables and an innovative analytical method, adapted in particular to the estimation of covariances and their propagation, the mass yields obtained present reduced uncertainties and a complete experimental covariance matrix. This is essential for understanding and using the measured data.The isotopic yields obtained are highly dependent on the nuclear structure data, and de facto present significant uncertainties. The future improvement of the nuclear structure data will allow, thanks to the analysis tools developed, to reduce the uncertainty of the isotopic yields measured.Other observables of interest have been extracted from the measurements, in particular the average kinetic energy distribution of the fission products as a function of their mass, as well as the charge polarization for part of the heavy peak. These data are complementary to fission yields and are of interest for models and future evaluations.; La fission nucléaire, bien que connue depuis 80 ans, reste un défi théorique. La complexité et la multiplicité des interactions au sein d’un noyau fissionnant rend la modélisation du phénomène de fission délicate. Les modèles de fission nucléaire peinent à reproduire les observables. Parmi ces observables, les rendements de fissions sont pourtant des ingrédients clés pour la physique des réacteurs. S’ils ne peuvent être prédis efficacement, il est nécessaire de les mesurer.Les bibliothèques de données nucléaires évaluées, qui condensent la connaissance actuelle de ces rendements de fission, présentent pourtant des incertitudes importantes, ainsi que des divergences.Depuis quelques années, une collaboration entre le CEA, le CNRS et l’Institut Laue Langevin (ILL) vise à mesurer avec précision les rendements de la fission induite par neutron thermique pour des actinides d’importance pour les cycles Uranium-Plutonium et Thorium-Uranium, afin de compléter les connaissances actuelles et également fournir des données de référence pour le test de modèles.En particulier, au cours de cette thèse, des données expérimentales, acquises sur le spectromètre de masse LOHENGRIN à l’ILL de Grenoble (France), ont été analysées pour le 239Pu(nth,f) et le 241Pu(nth,f). Deux types de rendements ont été déterminées : des rendements en masse, à l’aide d’une chambre d’ionisation, et des rendements isotopiques, par spectrométrie γ avec des détecteurs Ge.Grâce à un protocole expérimental rigoureux testant la reproductibilité des observables et une méthode d’analyse innovante, adaptée en particulier à l’estimation des covariances et à leurs propagations, les rendements en masse obtenus présentent des incertitudes réduites et une matrice de covariance expérimentale complète. Celle-ci est essentielle pour la compréhension et l’utilisation des données mesurées.Les rendements isotopiques obtenus sont fortement dépendants des données de structure nucléaire, et présentent de facto des incertitudes importantes. L’amélioration future des données de structure permettra, grâce aux outils d’analyse développés, de réduire l’incertitude des rendements isotopiques mesurés.D’autres observables d’intérêts ont pu être extraites des mesures, en particulier la distribution de l’énergie cinétique moyenne des produits de fission en fonction de leur masse, ainsi que la polarisation de charge pour une partie du pic lourd. Ces données sont complémentaires aux rendements et présentent un intérêt pour les modèles et les futures évaluations.
- Published
- 2018
10. Experimental and phenomenological approach of the neutron induced fission yields for 239Pu and 241Pu
- Author
-
Julien-Laferrière, Sylvain, Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS), Université Grenoble Alpes, Grégoire Kessedjian, Olivier Sérot, and STAR, ABES
- Subjects
Lohengrin ,Fifrelin ,[PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex] ,Fission yield ,[PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex] ,Rendement de fission ,Plutonium - Abstract
Nuclear fission, although known for 80 years, remains a theoretical challenge. The complexity and multiplicity of interactions within a splitting nucleus make the modelling of the fission phenomenon delicate. Nuclear fission models struggle to replicate observables. Among these observables, however, fission yields are key ingredients for reactor physics. If they cannot be predicted effectively, it is necessary to measure them.The evaluated nuclear data libraries, which condense the current knowledge of these fission yields, nevertheless present significant uncertainties, as well as discrepancies.For several years, a collaboration between the CEA, the CNRS and the Laue Langevin Institute (ILL) has aimed at accurately measuring the yields of thermal neutron induced fission for actinides of importance for the Uranium-Plutonium and Thorium-Uranium cycles, in order to complete current knowledge and also provide reference data for model testing.In particular, during this thesis, experimental data acquired on the LOHENGRIN mass spectrometer at the ILL in Grenoble (France) were analysed for 239Pu(nth,f) and 241Pu(nth,f). Two types of yields were determined: mass yields, using an ionization chamber, and isotopic yields, by spectrometry γ with Ge.Thanks to a rigorous experimental protocol testing the reproducibility of the observables and an innovative analytical method, adapted in particular to the estimation of covariances and their propagation, the mass yields obtained present reduced uncertainties and a complete experimental covariance matrix. This is essential for understanding and using the measured data.The isotopic yields obtained are highly dependent on the nuclear structure data, and de facto present significant uncertainties. The future improvement of the nuclear structure data will allow, thanks to the analysis tools developed, to reduce the uncertainty of the isotopic yields measured.Other observables of interest have been extracted from the measurements, in particular the average kinetic energy distribution of the fission products as a function of their mass, as well as the charge polarization for part of the heavy peak. These data are complementary to fission yields and are of interest for models and future evaluations., La fission nucléaire, bien que connue depuis 80 ans, reste un défi théorique. La complexité et la multiplicité des interactions au sein d’un noyau fissionnant rend la modélisation du phénomène de fission délicate. Les modèles de fission nucléaire peinent à reproduire les observables. Parmi ces observables, les rendements de fissions sont pourtant des ingrédients clés pour la physique des réacteurs. S’ils ne peuvent être prédis efficacement, il est nécessaire de les mesurer.Les bibliothèques de données nucléaires évaluées, qui condensent la connaissance actuelle de ces rendements de fission, présentent pourtant des incertitudes importantes, ainsi que des divergences.Depuis quelques années, une collaboration entre le CEA, le CNRS et l’Institut Laue Langevin (ILL) vise à mesurer avec précision les rendements de la fission induite par neutron thermique pour des actinides d’importance pour les cycles Uranium-Plutonium et Thorium-Uranium, afin de compléter les connaissances actuelles et également fournir des données de référence pour le test de modèles.En particulier, au cours de cette thèse, des données expérimentales, acquises sur le spectromètre de masse LOHENGRIN à l’ILL de Grenoble (France), ont été analysées pour le 239Pu(nth,f) et le 241Pu(nth,f). Deux types de rendements ont été déterminées : des rendements en masse, à l’aide d’une chambre d’ionisation, et des rendements isotopiques, par spectrométrie γ avec des détecteurs Ge.Grâce à un protocole expérimental rigoureux testant la reproductibilité des observables et une méthode d’analyse innovante, adaptée en particulier à l’estimation des covariances et à leurs propagations, les rendements en masse obtenus présentent des incertitudes réduites et une matrice de covariance expérimentale complète. Celle-ci est essentielle pour la compréhension et l’utilisation des données mesurées.Les rendements isotopiques obtenus sont fortement dépendants des données de structure nucléaire, et présentent de facto des incertitudes importantes. L’amélioration future des données de structure permettra, grâce aux outils d’analyse développés, de réduire l’incertitude des rendements isotopiques mesurés.D’autres observables d’intérêts ont pu être extraites des mesures, en particulier la distribution de l’énergie cinétique moyenne des produits de fission en fonction de leur masse, ainsi que la polarisation de charge pour une partie du pic lourd. Ces données sont complémentaires aux rendements et présentent un intérêt pour les modèles et les futures évaluations.
- Published
- 2018
11. New measurements on isobaric fission product yields and mean kinetic energy for 241Pu thermal neutron-induced fission.
- Author
-
Julien-Laferrière, Sylvain, Kessedjian, Grégoire, Serot, Olivier, Chebboubi, Abdelaziz, Bernard, David, Blanc, Aurélien, Köster, Ulli, Litaize, Olivier, Materna, Thomas, Meplan, Olivier, Rapala, Michal, and Sage, Christophe
- Subjects
- *
NUCLEAR fission , *THERMAL neutrons , *MASS spectrometers , *KINETIC energy , *ISOBARIC processes - Abstract
Nuclear fission yields data measurements for thermal neutron induced fission of 241Pu have been carried out at the Institut Laue Langevin (ILL) in Grenoble, using the Lohengrin mass spectrometer. Mass, isotopic and isomeric yields have been extracted for the last measurements. A focus is given in this document to the mass yield results which are obtained for almost the entire heavy peak and most of the light high yields masses, along with the covariance matrix. The mean kinetic energy as a function of the fission product mass has also been extracted from the measurements. The total mean kinetic energy pre and post neutron emission have been assessed and compared to other works showing a rather good agreement. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
12. Theoretical investigation of fission fragment kinetic energy distributions in the symmetric mass region for 233U(nth, f).
- Author
-
Chebboubi, Abdelaziz, Serot, Olivier, Kessedjian, Grégoire, Litaize, Olivier, Blanc, Aurelien, Bernard, David, Faust, Herbert, Julien-Laferrière, Sylvain, Köster, Ulli, Letourneau, Alain, Materna, Thomas, Méplan, Olivier, Mutti, Paolo, Rapala, Michal, and Sage, Christophe
- Subjects
NUCLEAR fission ,KINETIC energy ,URANIUM ,PROMPT neutrons ,NEUTRON multiplicity - Abstract
Fission yields are essential for nuclear reactor studies (decay heat, fuel inventory. . .) and constitute also one of the main observables needed to improve our understanding of the fission process. The symmetric mass region is of particular interest due to various intriguing properties of the fission fragments already reported in the literature : inversion of the nuclear charge polarization, large width of the fission fragment kinetic energy distribution, strong change of the prompt neutron multiplicity, etc. Recently, measurements of fission yields and kinetic energy distributions in the symmetric mass region were achieved at the LOHENGRIN mass spectrometer of the Institut Laue-Langevin (ILL). This experimental work is challenging due to the low counting rate and the appearance of contaminant masses, leading to pronounced components in the fission fragment kinetic energy distribution. Despite removing the undesirable contributions, the fission fragment kinetic energy distributions still show two components, indicating that the fission process could be modal. To go further and better characterize these components a comparison between our experimental data and Monte Carlo calculations (FIFRELIN code) simulating the de-excitation of the fission fragments for different fission channels will be presented and discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
13. A study of the construction of the correlation matrix of 241Pu(nth,f) isobaric fission yields.
- Author
-
de Saint Jean, Cyrille, Julien-Laferrière, Sylvain, Chebboubi, Abdelaziz, Kessedjian, Grégoire, and Serot, Olivier
- Subjects
ISOBARIC processes ,MONTE Carlo method ,COVARIANCE matrices ,THERMAL neutrons ,KINETIC energy - Abstract
Two blind analyses for
241 Pu(nth,f) isobaric fission yields have been conducted, one analysis using a mix of a Monte-Carlo and an analytical method, the other one relying only on analytical calculations. The calculations have been derived from the same analysis path and experimental data, obtained on the LOHENGRIN mass spectrometer at the Institut Laue-Langevin. The comparison between the two analyses put into lights several biases and limits of each analysis and gives a comprehensive vision on the construction of the correlation matrix. It gives confidence in the analysis scheme used for the determination of the fission yields and their correlation matrix. [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
- View/download PDF
14. From fission yield measurements to evaluation: status on statistical methodology for the covariance question.
- Author
-
de Saint Jean, Cyrille, Voirin, Brieuc, Kessedjian, Grégoire, Chebboubi, Abdelaziz, Julien-Laferrière, Sylvain, and Serot, Olivier
- Subjects
NUCLEAR fission ,ESTIMATION theory ,THERMAL neutrons ,ENTROPY ,STATISTICS - Abstract
Studies on fission yields have a major impact on the characterization and the understanding of the fission process and are mandatory for reactor applications. Fission yield evaluation represents the synthesis of experimental and theoretical knowledge to perform the best estimation of mass, isotopic and isomeric yields. Today, the output of fission yield evaluation is available as a function of isotopic yields. Without the explicitness of evaluation covariance data, mass yield uncertainties are greater than those of isotopic yields. This is in contradiction with experimental knowledge where the abundance of mass yield measurements is dominant. These last years, different covariance matrices have been suggested but the experimental part of those are neglected. The collaboration between the LPSC Grenoble and the CEA Cadarache starts a new program in the field of the evaluation of fission products in addition to the current experimental program at Institut Laue-Langevin. The goal is to define a new methodology of evaluation based on statistical tests to define the different experimental sets in agreement, giving different solutions for different analysis choices. This study deals with the thermal neutron induced fission of
235 U. The mix of data is non-unique and this topic will be discussed using the Shannon entropy criterion in the framework of the statistical methodology proposed. [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
- View/download PDF
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